1) Create calculater
implementation 'net.objecthunter:exp4j:0.4.8'
Button.xml
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_pressed="true">
        <shape>
            <gradient android:angle="90" android:endColor="#FFFFFF" android:startColor="#9EB8FF" android:type="linear"/>
            <padding android:bottom="0dp" android:left="0dp" android:right="0dp" android:top="0dp"/>
            <size android:width="60dp" android:height="60dp"/>
            <stroke android:width="1dp" android:color="#ff3da6ef"/>
        </shape>
    </item>
    <item>
        <shape>
            <gradient android:angle="90" android:endColor="#FFFFFF" android:startColor="#ffd9d9d9" android:type="linear"/>
            <padding android:bottom="0dp" android:left="0dp" android:right="0dp" android:top="0dp"/>
            <size android:width="60dp" android:height="60dp"/>
            <stroke android:width="0.5dp" android:color="#ffcecece"/>
        </shape>
    </item>
</selector>
MainActivity.kt
package com.javahelps.kotlincalculator
import android.os.Bundle
import android.support.v7.app.AppCompatActivity
import android.view.View
import android.widget.Button
import android.widget.TextView
import net.objecthunter.exp4j.ExpressionBuilder
class MainActivity : AppCompatActivity() {
    lateinit var txtInput: TextView
    var lastNumeric: Boolean = false
    var stateError: Boolean = false
    var lastDot: Boolean = false
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        txtInput = findViewById(R.id.txtInput)
    }
    fun onDigit(view: View) {
        if (stateError) {            txtInput.text = (view as Button).text
            stateError = false
        } else {
    txtInput.append((view as Button).text)
        {
        lastNumeric = true
    }
    fun onDecimalPoint(view: View) {
        if (lastNumeric && !stateError && !lastDot) {
            txtInput.append(".")
            lastNumeric = false
            lastDot = true
        }
    }
  fun onOperator(view: View) {
        if (lastNumeric && !stateError) {
            txtInput.append((view as Button).text)
            lastNumeric = false
            lastDot = false            }
    }
    fun onClear(view: View) {
        this.txtInput.text = ""
        lastNumeric = false
        stateError = false
        lastDot = false
    }
    fun onEqual(view: View) {
        if (lastNumeric && !stateError) {
            val txt = txtInput.text.toString()
            val expression = ExpressionBuilder(txt).build()
            try {
                val result = expression.evaluate()
                txtInput.text = result.toString()
                lastDot = true // Result contains a dot
            } catch (ex: ArithmeticException) {
                txtInput.text = "Error"
                stateError = true
                lastNumeric = false
            }
        }
    }
}
Activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:paddingTop="8dp"
        tools:context=".MainActivity">

    <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:ems="10"
            android:textSize="48sp"
            android:background="#efefef"
            android:id="@+id/txtInput"
            android:gravity="right|center_vertical"
            android:maxLength="12"
            android:layout_marginLeft="8dp"
            android:layout_marginEnd="8dp"
            android:layout_marginStart="8dp"
            app:layout_constraintTop_toTopOf="parent"
            android:layout_marginRight="8dp"/>
    <TableLayout
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_marginTop="8dp"
            app:layout_goneMarginTop="8dp"
            android:layout_marginLeft="8dp"
            android:layout_marginBottom="8dp"
            android:layout_marginRight="8dp"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintRight_toRightOf="parent"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/txtInput"
            android:gravity="fill">
        <TableRow
                android:layout_width="match_parent"
                android:layout_height="0dp"
                android:layout_weight="1"
                android:gravity="center">
            <Button
                    android:text="7"
                    android:background="@drawable/button"
                    android:layout_width="0dp"
                    android:layout_weight="1"
                    android:layout_height="match_parent"
                    android:onClick="onDigit"
                    android:id="@+id/btnSeven"/>
            <Button
                    android:text="8"
                    android:background="@drawable/button"
                    android:layout_width="0dp"
                    android:layout_weight="1"
                    android:layout_height="match_parent"
                    android:onClick="onDigit"
                    android:id="@+id/btnEight"/>
            <Button
                    android:text="9"
                    android:background="@drawable/button"
                    android:layout_width="0dp"
                    android:layout_weight="1"
                    android:layout_height="match_parent"
                    android:onClick="onDigit"
                    android:id="@+id/btnNine"/>
            <Button
                    android:text="/"
                    android:background="@drawable/button"
                    android:layout_width="0dp"
                    android:layout_weight="1"
                    android:layout_height="match_parent"
                    android:onClick="onOperator"
                    android:id="@+id/btnDivide"/>
        </TableRow>

        <TableRow
                android:layout_width="match_parent"
                android:layout_height="0dp"
                android:layout_weight="1"
                android:gravity="center">

            <Button
                    android:text="4"
                    android:background="@drawable/button"
                    android:layout_width="0dp"
                    android:layout_weight="1"
                    android:layout_height="match_parent"
                    android:onClick="onDigit"
                    android:id="@+id/btnFour"/>

            <Button
                    android:text="5"
                    android:background="@drawable/button"
                    android:layout_width="0dp"
                    android:layout_weight="1"
                    android:layout_height="match_parent"
                    android:onClick="onDigit"
                    android:id="@+id/btnFive"/>

            <Button
                    android:text="6"
                    android:background="@drawable/button"
                    android:layout_width="0dp"
                    android:layout_weight="1"
                    android:layout_height="match_parent"
                    android:onClick="onDigit"
                    android:id="@+id/btnSix"/>

            <Button
                    android:text="*"
                    android:background="@drawable/button"
                    android:layout_width="0dp"
                    android:layout_weight="1"
                    android:layout_height="match_parent"
                    android:onClick="onOperator"
                    android:id="@+id/btnMultiply"/>
        </TableRow>

        <TableRow
                android:layout_width="match_parent"
                android:layout_height="0dp"
                android:layout_weight="1"
                android:gravity="center">

            <Button
                    android:text="1"
                    android:background="@drawable/button"
                    android:layout_width="0dp"
                    android:layout_weight="1"
                    android:layout_height="match_parent"
                    android:onClick="onDigit"
                    android:id="@+id/btnOne"/>

            <Button
                    android:text="2"
                    android:background="@drawable/button"
                    android:layout_width="0dp"
                    android:layout_weight="1"
                    android:layout_height="match_parent"
                    android:onClick="onDigit"
                    android:id="@+id/btnTwo"/>

            <Button
                    android:text="3"
                    android:background="@drawable/button"
                    android:layout_width="0dp"
                    android:layout_weight="1"
                    android:layout_height="match_parent"
                    android:onClick="onDigit"
                    android:id="@+id/btnThree"/>

            <Button
                    android:text="-"
                    android:background="@drawable/button"
                    android:layout_width="0dp"
                    android:layout_weight="1"
                    android:layout_height="match_parent"
                    android:onClick="onOperator"
                    android:id="@+id/btnSubtract"/>
        </TableRow>

        <TableRow
                android:layout_width="match_parent"
                android:layout_height="0dp"
                android:layout_weight="1"
                android:gravity="center">

            <Button
                    android:text="."
                    android:background="@drawable/button"
                    android:layout_width="0dp"
                    android:layout_weight="1"
                    android:layout_height="match_parent"
                    android:onClick="onDecimalPoint"
                    android:id="@+id/btnDecimal"/>

            <Button
                    android:text="0"
                    android:background="@drawable/button"
                    android:layout_width="0dp"
                    android:layout_weight="1"
                    android:layout_height="match_parent"
                    android:onClick="onDigit"
                    android:id="@+id/btnZero"/>

            <Button
                    android:text="CLR"
                    android:background="@drawable/button"
                    android:layout_width="0dp"
                    android:layout_weight="1"
                    android:layout_height="match_parent"
                    android:onClick="onClear"
                    android:id="@+id/btnClear"/>

            <Button
                    android:text="+"
                    android:background="@drawable/button"
                    android:layout_width="0dp"
                    android:layout_weight="1"
                    android:layout_height="match_parent"
                    android:onClick="onOperator"
                    android:id="@+id/btnAdd"/>
        </TableRow>

        <TableRow
                android:layout_width="match_parent"
                android:layout_height="0dp"
                android:layout_weight="1">

            <Button
                    android:text="="
                    android:background="@drawable/button"
                    android:layout_width="0dp"
                    android:layout_weight="1"
                    android:layout_height="match_parent"
                    android:onClick="onEqual"
                    android:id="@+id/btnEqual"/>
        </TableRow>
    </TableLayout>
</android.support.constraint.ConstraintLayout>

2) create menu item and also add toast
menubar.xml
     res-new-android resource-manu.
     mamu-new-resource file.
<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto">
    <item android:id="@+id/home"
    android:icon="@drawable/img"
          app:showAsAction="always"
          android:title="Home">

    </item>
    <item android:id="@+id/refresh"
          android:icon="@drawable/img"
          app:showAsAction="always"
          android:title="Refresh"/>
    <item android:id="@+id/delete"
          android:icon="@drawable/img"
          app:showAsAction="always"
          android:title="Delete"/>
</menu>

MainActivity.kt
package com.example.dialog
import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.support.v7.app.AlertDialog
import android.view.Menu
import android.view.MenuItem
import android.widget.Toast
class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
    }
    override fun onCreateOptionsMenu(menu: Menu?): Boolean {
        val inflater= menuInflater
        inflater.inflate(R.menu.menubar,menu)
        return super.onCreateOptionsMenu(menu)
    }
    override fun onOptionsItemSelected(item: MenuItem?): Boolean {
        if (item!=null){
            when(item.itemId){
                R.id.home->{
                    Toast.makeText(applicationContext,"Home",Toast.LENGTH_SHORT).show()
                }
                R.id.refresh->{
                    Toast.makeText(applicationContext,"Refresh",Toast.LENGTH_SHORT).show()
                }
                R.id.delete->{
                    Toast.makeText(applicationContext,"Delete",Toast.LENGTH_SHORT).show()
                    alert()
                }
            }
        }
        return super.onOptionsItemSelected(item)
    }
    private fun alert()
    {
        val builder=AlertDialog.Builder(this)
        builder.setTitle("Simple Alert")
        builder.setMessage("Alerrt Msg")
        builder.setPositiveButton("yes")
        {
            dialog, which -> Toast.makeText(applicationContext,"ButtonClick",Toast.LENGTH_SHORT).show()
        }
        val dialog:AlertDialog=builder.create()
        dialog.show()
    }
}
Activitymain.kt
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MainActivity">
    <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Hello World!"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintRight_toRightOf="parent"
            app:layout_constraintTop_toTopOf="parent"/>
</android.support.constraint.ConstraintLayout>

second slip
1-AlertDialog

activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MainActivity">

    <Button android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="show alert"
            android:textAllCaps="false"
            android:id="@+id/dialog"/>

</RelativeLayout>

Mainactivity.kt

package com.example.loginpage

import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.support.v7.app.AlertDialog
import android.widget.Toast
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
    }
    override fun onBackPressed() {
        val builder =AlertDialog.Builder(this@MainActivity)
        builder.setTitle("are you sure")
        builder.setMessage("are you want to close app")
        builder.setPositiveButton("yes",{dialogInterfac,i->finish()})
        builder.setNegativeButton("no",{dialogInterfac,i->finish()})
        builder.show();
    }
}
2-pass data from one page to another using intent
MainActivity.kt

package com.example.intent

import android.content.Intent
import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.widget.Button
import android.widget.EditText
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {
val name = null
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        val btn=findViewById<Button>(R.id.btn1)
        var message=findViewById<EditText>(R.id.edttxt)
        btn.setOnClickListener{
            val intent=Intent(this,Main2Activity::class.java)
            var name= message.text.toString()
            intent.putExtra("message",message.text.toString())
            startActivity(intent)
        }
    }
}


Activitymain.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MainActivity">

    <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Enter Name!"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintRight_toRightOf="parent"
            android:id="@+id/txt"
            android:textSize="25dp"
            app:layout_constraintTop_toTopOf="parent"/>
    <EditText
              android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:id="@+id/edttxt"
              android:layout_toRightOf="@+id/txt"
    />

    <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/btn1"
            android:text="Submit"
            android:textSize="20dp"
            android:layout_below="@+id/txt"
            android:layout_marginTop="20dp"
    />
</RelativeLayout>
ActivitySecond.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".Main2Activity">
    <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textSize="25dp"
            android:textStyle="bold"
            android:layout_centerInParent="true"
            android:id="@+id/text1"
    />
</RelativeLayout>
main2activity.kt
package com.example.intent
import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.widget.TextView
class Main2Activity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_second)
        var strUser: String = intent.getStringExtra("message")
        val n = findViewById<TextView>(R.id.text1)
        n.text="Welcome " + strUser
    }
}


..3 Android resource program:
colors.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
    <color name="colorPrimary">#008577</color>
    <color name="colorPrimaryDark">#00574B</color>
    <color name="colorAccent">#D81B60</color>
</resources>
styles.xml
<resources>
    <!-- Base application theme. -->
    <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
        <!-- Customize your theme here. -->
        <item name="colorPrimary">@color/colorPrimary</item>
        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
        <item name="colorAccent">@color/colorAccent</item>
    </style>

</resources>

string.xml

<resources>
    <string name="Hello_kotlin"></string>
       <string name="numbers">
        <item>1</item>
        <item>2</item>
        <item>3</item>
    </string>
</resources>


AndroidMAnifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
          package="com.example.hello_kotlin">

    <application
            android:allowBackup="true"
            android:icon="@mipmap/ic_launcher"
            android:label="@string/numbers"

            android:roundIcon="@mipmap/ic_launcher_round"
            android:supportsRtl="true"
            android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>

                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>
    </application>

</manifest>



Acitvitymain.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@drawable/download"
        tools:context=".MainActivity">
    <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Click"
            android:layout_centerInParent="true"
            android:id="@+id/button" />
    <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/numbers"
            android:textSize="20dp"
            android:layout_below="@id/button"
            android:textColor="#ffff"
    />
</RelativeLayout>
activity_main.xml


4. create calculator using grid
<?xml version="1.0" encoding="utf-8"?>
<GridLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MainActivity"
        android:layout_gravity="center"
        android:padding="16dp"
        android:rowCount="6"
        android:columnCount="4">
    <EditText
            android:layout_width="353dp"
            android:layout_height="wrap_content"
            android:inputType="textPersonName"
            android:ems="10"
            android:id="@+id/et_number"
            android:layout_columnSpan="4"/>
    <Button
            android:text="DEL"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" android:id="@+id/btn_del"
            android:layout_row="1"
            android:layout_column="0"
    />
    <Button
            android:text="C"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" android:id="@+id/btn_clear"
            android:layout_row="1"
            android:layout_column="1"/>
    <Button
            android:text="%"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" android:id="@+id/btn_mod"
            android:layout_row="1"
            android:layout_column="2"/>
    <Button
            android:text="+"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" android:id="@+id/btn_add"
            android:layout_row="1"
            android:layout_column="3"/>
    <Button
            android:text="1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/btn_no1"
            android:layout_row="2"
            android:layout_column="0"/>
    <Button
            android:text="2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" android:id="@+id/btn_no2"
            android:layout_row="2"
            android:layout_column="1"/>
    <Button
            android:text="3"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" android:id="@+id/btn_no3"
            android:layout_row="2"
            android:layout_column="2"/>
    <Button
            android:text="/"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" android:id="@+id/btn_divide"
            android:layout_row="2"
            android:layout_column="3"/>
    <Button
            android:text="4"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" android:id="@+id/btn_no4"
            android:layout_row="3"
            android:layout_column="0"/>
    <Button
            android:text="5"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" android:id="@+id/btn_no5"
            android:layout_row="3"
            android:layout_column="1"/>
    <Button
            android:text="6"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" android:id="@+id/btn_no6"
            android:layout_row="3"
            android:layout_column="2"/>
    <Button
            android:text="-"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" android:id="@+id/btn_subtract"
            android:layout_row="3"
            android:layout_column="3"/>
    <Button
            android:text="7"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" android:id="@+id/btn_no7"
            android:layout_row="4"
            android:layout_column="0"/>
    <Button
            android:text="8"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" android:id="@+id/btn_no8"
            android:layout_row="4"
            android:layout_column="1"/>
    <Button
            android:text="9"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" android:id="@+id/btn_no9"
            android:layout_row="4"
            android:layout_column="2"/>
    <Button
            android:text="x"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" android:id="@+id/btn_multiply"
            android:layout_row="4"
            android:layout_column="3"/>
    <Button
            android:text="Button"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" android:id="@+id/button18"
            android:layout_row="5"
            android:layout_column="0"/>
    <Button
            android:text="0"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_row="5"
            android:layout_column="1"
            android:id="@+id/btn_no0"/>
    <Button
            android:text="="
            android:layout_width="171dp"
            android:layout_height="wrap_content" android:id="@+id/btn_answer"
            android:layout_row="5"
            android:layout_column="2"
            android:layout_columnSpan="2"/>
</GridLayout>

MainActivity.kt
import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.widget.Toast
import kotlinx.android.synthetic.main.activity_main.*
class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        var num_1 = 0
        var num_2 = 0
        var operator =""
        var answer = 0
        var answer_2 = 0.0
        //Button 0-9
        btn_no1.setOnClickListener {
            et_number.append("1").toString()
        }
        btn_no2.setOnClickListener {
            et_number.append("2").toString()
        }
        btn_no3.setOnClickListener {
            et_number.append("3").toString()
        }
        btn_no4.setOnClickListener {
            et_number.append("4").toString()
        }
        btn_no5.setOnClickListener {
            et_number.append("5").toString()
        }
        btn_no6.setOnClickListener {
            et_number.append("6").toString()
        }
        btn_no7.setOnClickListener {
            et_number.append("7").toString()
        }
        btn_no8.setOnClickListener {
            et_number.append("8").toString()
        }
        btn_no9.setOnClickListener {
            et_number.append("9").toString()
        }
        btn_no0.setOnClickListener {
            et_number.append("0").toString()
        }
        btn_add.setOnClickListener {
            num_1 = et_number.text.toString().toInt()
            et_number.setText("")
            et_number.setHint("+")
            operator = "+"
        }
        btn_divide.setOnClickListener {
            num_1 = et_number.text.toString().toInt()
            et_number.setText("")
            et_number.setHint("/")
            operator = "/"
        }
        btn_multiply.setOnClickListener {
            num_1 = et_number.text.toString().toInt()
            et_number.setText("")
            et_number.setHint("*")
            operator = "*"
        }
        btn_subtract.setOnClickListener {
            num_1 = et_number.text.toString().toInt()
            et_number.setText("")
            et_number.setHint("-")
            operator = "-"
        }
        btn_mod.setOnClickListener {
            num_1 = et_number.text.toString().toInt()
            et_number.setText("")
            et_number.setHint("%")
            operator = "%"
        }
        btn_clear.setOnClickListener {
            num_1 = 0
            num_2 = 0
            answer = 0
            operator = ""
            et_number.setHint("")
            et_number.setText("")
        }
        btn_del.setOnClickListener {
            var temp = et_number.text.toString().toInt()
            var ans = temp /10
            et_number.setText(ans.toString())
        }
        btn_answer.setOnClickListener {
            num_2 = et_number.text.toString().toInt()
            et_number.setText("")
            et_number.setHint("")
            if (operator.equals("+")){
                answer = num_1 + num_2
                Toast.makeText(this, answer.toString(), Toast.LENGTH_LONG).show()
            }
            else if (operator.equals("-")){
                answer = num_1 - num_2
                Toast.makeText(this, answer.toString(), Toast.LENGTH_LONG).show()
            }
            else if (operator.equals("/")){
                answer = num_1 / num_2
                Toast.makeText(this, answer.toString(), Toast.LENGTH_LONG).show()
            }
            else if (operator.equals("*")){
                answer = num_1 * num_2
                Toast.makeText(this, answer.toString(), Toast.LENGTH_LONG).show()
            }else if (operator.equals("%")){
                answer_2 = num_1.toDouble() % num_2.toDouble()
                Toast.makeText(this, answer_2.toString(), Toast.LENGTH_LONG).show()
            }else{
                Toast.makeText(this, "Wrong Input", Toast.LENGTH_LONG).show()
            }
        }
    }
}
5: create areoplane mode
activity_main.XML

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MainActivity">

        <ImageView
                android:id="@+id/imageview"
                android:layout_width="40dp"
                android:layout_height="40dp"
                android:layout_marginTop="8dp"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toTopOf="parent"
                app:srcCompat="@drawable/ic_flight_black_24dp"
                tools:ignore="VectorDrawableCompat"/>
        <TextView
                android:id="@+id/textview1"
                android:layout_width="300dp"
                android:layout_height="36dp"

                android:text="Flight Mode"
                android:textSize="24dp"
                android:textColor="@android:color/black"

                android:layout_toRightOf="@+id/imageview"
                android:layout_marginLeft="45dp"/>
</RelativeLayout>


androidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
          package="com.example.flight_mode">

    <application
            android:allowBackup="true"
            android:icon="@mipmap/ic_launcher"
            android:label="@string/app_name"
            android:roundIcon="@mipmap/ic_launcher_round"
            android:supportsRtl="true"
            android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>
                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>
        <receiver android:name=".myreciver"
                  android:enabled="true"
                  android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.AIRPLANE_MODE"></action>
            </intent-filter>
        </receiver>
    </application>
</manifest>


myreciver.kt


package com.example.flight_mode
import android.content.BroadcastReceiver
import android.content.Context
import android.content.Intent
import android.widget.Toast
class myreciver:BroadcastReceiver() {
    override fun onReceive(context: Context, intent: Intent) {
        Toast.makeText(
            context, "Broadcast : Flight mode changed.",
            Toast.LENGTH_LONG
        ).show()
    }
}

MainActivity.kt

package com.example.flight_mode
import android.content.IntentFilter
import android.os.Bundle
import android.support.v7.app.AppCompatActivity
import java.util.logging.Filter

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        val filter=IntentFilter()
        filter.addAction("com.example.flight_mode")
        filter.addAction("android.intent.action.AIRPLANE_MODE")
        val reciver=myreciver()
        registerReceiver(reciver,filter)
    }
}
6: create application using image view
activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<GridLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MainActivity" android:columnCount="3" android:rowCount="3">
    <ImageView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" app:srcCompat="@mipmap/ic_launcher_round" android:id="@+id/imageView"
            android:layout_row="0" android:layout_column="0"/>
    <ImageView
            android:layout_width="40dp"
            android:layout_height="40dp" app:srcCompat="@drawable/ic_assignment_ind_black_24dp"
            android:id="@+id/imageView2" android:layout_row="0" android:layout_column="1"/>
    <ImageView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" app:srcCompat="@mipmap/ic_launcher_round"
            android:id="@+id/imageView3"
            android:layout_row="0" android:layout_column="2"/>
    <ImageView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" app:srcCompat="@mipmap/ic_launcher_round"
            android:id="@+id/imageView4"
            android:layout_row="1" android:layout_column="0"/>
    <ImageView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" app:srcCompat="@mipmap/ic_launcher_round"
            android:id="@+id/imageView5"
            android:layout_row="1" android:layout_column="1"/>
    <ImageView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" app:srcCompat="@mipmap/ic_launcher_round"
            android:id="@+id/imageView6"
            android:layout_row="1" android:layout_column="2"/>
</GridLayout>

MainActivity.kt

package com.trackrider.android.gridviewimage
import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.widget.Toast
import kotlinx.android.synthetic.main.activity_main.*
class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        //change text in toast as required
        imageView.setOnClickListener {
            Toast.makeText(this, "Image 1", Toast.LENGTH_LONG).show()
        }
        imageView2.setOnClickListener {
            Toast.makeText(this, "Image 2", Toast.LENGTH_LONG).show()
        }
        imageView3.setOnClickListener {
            Toast.makeText(this, "Image 3", Toast.LENGTH_LONG).show()
        }
        imageView4.setOnClickListener {
            Toast.makeText(this, "Image 4", Toast.LENGTH_LONG).show()
        }
        imageView5.setOnClickListener {
            Toast.makeText(this, "Image 5", Toast.LENGTH_LONG).show()
        }
        imageView6.setOnClickListener {
            Toast.makeText(this, "Image 6", Toast.LENGTH_LONG).show()
        }
    }
}

7: life cycle program
ActivityMain.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MainActivity">

    <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Welcome!"
            android:textSize="30dp"
            android:layout_centerInParent="true"
            />
  </RelativeLayout>

MainActivity.kt

package com.example.life_cycle

import android.content.Intent
import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.widget.Button
import android.widget.Toast

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)


    }

    override fun onStart() {
        super.onStart()
        Toast.makeText(applicationContext, "app Started..", Toast.LENGTH_LONG).show()
    }

    override fun onResume() {
        super.onResume()
        Toast.makeText(applicationContext,"Resumed",Toast.LENGTH_LONG).show()
    }

    override fun onRestart() {
        super.onRestart()
        Toast.makeText(applicationContext,"Activity restarted",Toast.LENGTH_LONG).show()
    }

    override fun onPause() {
        super.onPause()
        Toast.makeText(applicationContext,"Activity Paused",Toast.LENGTH_LONG).show()
    }

    override fun onDestroy() {
        super.onDestroy()
        Toast.makeText(applicationContext,"Activity destroyed",Toast.LENGTH_LONG).show()
    }

    override fun onStop() {
        super.onStop()
        Toast.makeText(applicationContext,"Activity stoped",Toast.LENGTH_LONG).show()
    }

}


ActivityOne.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".Activity_one">

</android.support.constraint.ConstraintLayout>


Activityone.kt

package com.example.life_cycle

import android.support.v7.app.AppCompatActivity
import android.os.Bundle

class Activity_one : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_one)
    }
}
8:list view program
list view

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                                             android:layout_width="match_parent"
                                             android:layout_height="match_parent">


    <TextView android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:text="ListView"
              android:textSize="40dp"/>

    <ListView android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:entries="@array/insert_list">
    </ListView>

</RelativeLayout>

string.xml


<resources>
    <string name="app_name">Linear_Layout</string>

    <resources>
        <array name="insert_list">
            <item>one</item>
            <item>two</item>
            <item>three</item>
            <item>four</item>
            <item>five</item>
            <item>six</item>
            <item>seven</item>
            <item>eight</item>
            <item>nine</item>
            <item>ten</item>
        </array>
    </resources>

</resources>

9:login page program
activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MainActivity">


    <EditText
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:inputType="textPersonName"
            android:ems="10"
            android:id="@+id/et_username"
            android:hint="Username" app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintStart_toStartOf="parent" android:layout_marginTop="260dp"
            app:layout_constraintEnd_toEndOf="parent"/>
    <EditText
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:inputType="textPassword"
            android:ems="10"
            android:id="@+id/et_password"
            android:hint="Password" app:layout_constraintStart_toStartOf="@+id/et_username"
            android:layout_marginTop="22dp" app:layout_constraintTop_toBottomOf="@+id/et_username"/>
    <TextView
            android:text="Login"
            android:layout_width="86dp"
            android:layout_height="61dp"
            android:id="@+id/textView" android:textSize="30sp"
            android:textColor="@color/colorPrimaryDark" android:textStyle="bold"
            app:layout_constraintStart_toStartOf="parent" app:layout_constraintEnd_toEndOf="parent"
            android:layout_marginBottom="14dp" app:layout_constraintBottom_toTopOf="@+id/et_username"/>
    <Button
            android:text="Submit"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/btn_submit"
            app:layout_constraintStart_toStartOf="@+id/et_password"
            app:layout_constraintBaseline_toBaselineOf="@+id/btn_reset"/>
    <Button
            android:text="Reset"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/btn_reset" android:layout_marginTop="39dp"
            app:layout_constraintTop_toBottomOf="@+id/et_password" app:layout_constraintEnd_toEndOf="@+id/et_password"/>
    <android.support.constraint.Constraints android:layout_width="wrap_content" android:layout_height="wrap_content"
                                            android:id="@+id/constraints" app:layout_constraintTop_toTopOf="parent"
                                            app:layout_constraintStart_toStartOf="parent"
                                            app:layout_constraintEnd_toStartOf="parent"
                                            app:layout_constraintBottom_toTopOf="parent"/>
</android.support.constraint.ConstraintLayout>

MainActivity.kt

import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.widget.Button
import android.widget.EditText
import android.widget.Toast
class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        var mUsername = findViewById<EditText>(R.id.et_username)
        var mPassword = findViewById<EditText>(R.id.et_password)
        var mBtnSubmit = findViewById<Button>(R.id.btn_submit)
        var mBtnReset = findViewById<Button>(R.id.btn_reset)
        mBtnReset.setOnClickListener {
            mUsername.setText("")
            mPassword.setText("")
        }
        mBtnSubmit.setOnClickListener {
            var uname = mUsername.text.toString()
            var pwd = mPassword.text.toString()
            if(uname.equals("abcd") && pwd.equals("abcd")){
                Toast.makeText(this, “Login Successful”, Toast.LENGTH_LONG).show()
            }else{
                Toast.makeText(this, "Login Denied", Toast.LENGTH_LONG).show()
            }
        }
    }
}
10: permission program
ActivityMain.kt


<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MainActivity">

    <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/button1"

            tools:ignore="MissingConstraints" tools:layout_editor_absoluteY="134dp"
            tools:layout_editor_absoluteX="16dp"
    android:text="Request permission At Runtime"/>
</android.support.constraint.ConstraintLayout>


MainActivity.kt

package com.example.permission

import android.Manifest
import android.content.Context
import android.os.Build
import kotlinx.android.synthetic.main.activity_main.*
import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.widget.Toast




class MainActivity : AppCompatActivity() {
    private val PermissionsRequestCode = 123
    private lateinit var managePermissions: ManagePermissions


    override fun onCreate(savedInstanceState: Bundle?) {
            super.onCreate(savedInstanceState)
            setContentView(R.layout.activity_main)
            val list = listOf<String>(
                Manifest.permission.CAMERA,
                Manifest.permission.READ_CONTACTS,
                Manifest.permission.READ_EXTERNAL_STORAGE,
                Manifest.permission.SEND_SMS,
                Manifest.permission.READ_CALENDAR
            )

        managePermissions = ManagePermissions(this, list, PermissionsRequestCode)


       button1.setOnClickListener{
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M)
                managePermissions.checkPermissions()
        }

    }
        override fun onRequestPermissionsResult(requestCode: Int, permissions: Array<String>,
                                                grantResults: IntArray) {
            when (requestCode) {
                PermissionsRequestCode ->{
                    val isPermissionsGranted = managePermissions
                        .processPermissionsResult(requestCode,permissions,grantResults)
                    if(isPermissionsGranted){
                        // Do the task now
                        toast("Permissions granted.")
                    }else{
                        toast("Permissions denied.")
                    }
                    return
                }
            }
        }
    }
    // Extension function to show toast message
    fun Context.toast(message: String) {
        Toast.makeText(this, message, Toast.LENGTH_LONG).show()
    }



MAnagepermissions.kt


package com.example.permission

import android.app.Activity
import android.app.AlertDialog
import android.content.pm.PackageManager
import android.support.v4.app.ActivityCompat
import android.support.v4.content.ContextCompat


class ManagePermissions(val activity: Activity,val list: List<String>,val code:Int) {

    // Check permissions at runtime
    fun checkPermissions() {
        if (isPermissionsGranted() != PackageManager.PERMISSION_GRANTED) {
            showAlert()
        } else {
            activity.toast("Permissions already granted.")
        }
    }
    // Check permissions status
    private fun isPermissionsGranted(): Int {
        // PERMISSION_GRANTED : Constant Value: 0
        // PERMISSION_DENIED : Constant Value: -1
        var counter = 0;
        for (permission in list) {
            counter += ContextCompat.checkSelfPermission(activity, permission)
        }
        return counter
    }
    // Find the first denied permission
    private fun deniedPermission(): String {
        for (permission in list) {
            if (ContextCompat.checkSelfPermission(activity, permission)
                == PackageManager.PERMISSION_DENIED) return permission
        }
        return ""
    }
    // Show alert dialog to request permissions
    private fun showAlert() {
        val builder = AlertDialog.Builder(activity)
        builder.setTitle("Need permission(s)")
        builder.setMessage("Some permissions are required to do the task.")
        builder.setPositiveButton("OK", { dialog, which -> requestPermissions() })
        builder.setNeutralButton("Cancel", null)
        val dialog = builder.create()
        dialog.show()
    }
    // Request the permissions at run time
    private fun requestPermissions() {
        val permission = deniedPermission()
        if (ActivityCompat.shouldShowRequestPermissionRationale(activity, permission)) {
            // Show an explanation asynchronously
            activity.toast("Should show an explanation.")
        } else {
            ActivityCompat.requestPermissions(activity, list.toTypedArray(), code)
        }
    }
    // Process permissions result
    fun processPermissionsResult(requestCode: Int, permissions: Array<String>,
                                 grantResults: IntArray): Boolean {
        var result = 0
        if (grantResults.isNotEmpty()) {
            for (item in grantResults) {
                result += item
            }
        }
        if (result == PackageManager.PERMISSION_GRANTED) return true
        return false
    }
}


AndoridManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
          package="com.example.permission">

    <uses-permission android:name="android.permission.INTERNET"></uses-permission>
    <uses-permission android:name="android.permission.CAMERA"></uses-permission>
    <uses-permission android:name="android.permission.READ_CONTACTS"></uses-permission>
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"></uses-permission>
    <uses-permission android:name="android.permission.SEND_SMS"></uses-permission>
    <uses-permission android:name="android.permission.READ_CALENDAR"></uses-permission>

    <application
            android:allowBackup="true"
            android:icon="@mipmap/ic_launcher"
            android:label="@string/app_name"
            android:roundIcon="@mipmap/ic_launcher_round"
            android:supportsRtl="true"
            android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>

                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>
    </application>

</manifest>

string.xml
<resources>
    <string name="app_name">Permission</string>
</resources>

12: ringtone program
activity.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        android:background="@color/colorAccent"
        tools:context=".MainActivity">

    <Button
            android:id="@+id/button_play"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Play Default Ringtone"
            android:layout_gravity="center_horizontal"
            android:layout_margin="10dp"
    />
    <Button
            android:id="@+id/button_stop"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Stop"
            android:layout_gravity="center_horizontal"
            android:layout_margin="10dp"
    />
    <Button
            android:id="@+id/button_media_play"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Play Using Media Player"
            android:layout_gravity="center_horizontal"
            android:layout_margin="10dp"
    />
    <Button
            android:id="@+id/button_media_stop"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Stop Media Player"
            android:layout_gravity="center_horizontal"
            android:layout_margin="10dp"
    />

</LinearLayout>

activity.kt

package com.example.back_sound_service

import android.content.Context
import android.media.MediaPlayer
import android.media.Ringtone
import android.media.RingtoneManager
import android.media.audiofx.BassBoost
import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.provider.Settings
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val ringtone: Ringtone = defaultRingtone
               button_play.setOnClickListener{
            if (!ringtone.isPlaying){
                ringtone.play()
            }
        }

        button_stop.setOnClickListener{
            if (ringtone.isPlaying){
                ringtone.stop()
            }
        }
        val mediaPlayer:MediaPlayer = defaultRingtonePlayer()
        button_media_play.setOnClickListener{
            if (!mediaPlayer.isPlaying)mediaPlayer.start()
        }
        button_media_stop.setOnClickListener{
            if (mediaPlayer.isPlaying){
                mediaPlayer.stop()
            }
        }
    }
}
val Context.defaultRingtone:Ringtone
    get() {
        val uri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_RINGTONE)
        return RingtoneManager.getRingtone(this, uri)
    }
fun Context.defaultRingtonePlayer():MediaPlayer{
    return MediaPlayer.create(this, Settings.System.DEFAULT_RINGTONE_URI)
}
13:table layout program
table layout

<RelativeLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="#e6f0ff"
        tools:context=".MainActivity">
    <TableLayout android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:layout_marginLeft="50dp"
                 android:layout_marginTop="150dp"
                 android:background="#cce0ff">
        <TableRow>
            <Button
                    android:id="@+id/btn1"
                    android:text="1"
                    android:layout_gravity="center"
            />
            <Button
                    android:id="@+id/btn2"
                    android:text="2"
                    android:layout_gravity="center"
            />
            <Button
                    android:id="@+id/btn3"
                    android:text="3"
                    android:layout_gravity="center"
            />
        </TableRow>
        <TableRow>
            <Button
                    android:id="@+id/btn4"
                    android:text="4"
                    android:layout_gravity="center"
            />
            <Button
                    android:id="@+id/btn5"
                    android:text="5"
                    android:layout_gravity="center"
            /><Button
                android:id="@+id/btn6"
                android:text="6"
                android:layout_gravity="center"
        />
        </TableRow>
        <TableRow>
            <Button
                    android:id="@+id/btn7"
                    android:text="7"
                    android:layout_gravity="center"


            />
            <Button
                    android:id="@+id/btn8"
                    android:text="8"
                    android:layout_gravity="center"
            /><Button
                android:id="@+id/btn9"
                android:text="9"
                android:layout_gravity="center"
        />
        </TableRow>
    </TableLayout>
    <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"

            android:id="@+id/linearl"
            android:text="LinearLayout"
    />
    <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"

            android:id="@+id/relativel"
            android:layout_toRightOf="@+id/linearl"
            android:text="RelativeLayou"
    />

    <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"

            android:id="@+id/fragmentl"
            android:layout_toRightOf="@+id/relativel"
            android:text="fragmentLayout" />
    <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"

            android:id="@+id/listview"
           android:layout_below="@+id/linearl"
            android:text="ListView"   />
    <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"

            android:id="@+id/gridview"
            android:layout_toRightOf="@+id/listview"
            android:layout_below="@+id/linearl"
            android:text="ListView"   />
</RelativeLayout>