LoginSystem

package com.example.ayob.loginsystem;

import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {


    EditText userTxt;
    EditText passTxt ;
      SharedPreferences Prefs;
      SharedPreferences.Editor editor;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        setPointers();
        Toast.makeText(this,Prefs.getString("logged", "Error"),Toast.LENGTH_SHORT).show();

        if(CheckUser())
        {
            Intent intent=new Intent(this,Display_Activity.class);
            // Send  user name to Logged screen
            intent.putExtra("userinput", Prefs.getString("logged", "Error"));
            // Go to Disply logged screen
            this.startActivity(intent);
        }

    }
    // Checking if user exist in the SharedPreferences XML file

    private boolean CheckUser()
    {

        String userName = Prefs.getString("logged","Error");
        // If user not exist return false
        return (!userName.equals("Error"));
    }

     //pointer  initioialazation
    private void setPointers()
    {

         Prefs =    getApplicationContext().getSharedPreferences("users",MODE_PRIVATE);
         editor =   Prefs.edit();
         userTxt = (EditText)findViewById(R.id.txt_userName);
         passTxt = (EditText)findViewById(R.id.txt_Password);
    }
 // show Registeration Activity
    public void btn_show_register(View v)
    {
        Intent reg=new Intent(this,RegisterActivity.class);
        startActivity(reg);
    }
   // Login To the System
   public void btnLogin(View v)
   {

       SharedPreferences pref = getApplicationContext().getSharedPreferences("users", MODE_PRIVATE);

       String logUserName=userTxt.getText().toString().toLowerCase();
       String logPassword=passTxt.getText().toString();
       String loggeedUser=pref.getString(logUserName, "Error");

       // validate user input not empty
       if(logUserName.isEmpty() || logPassword.isEmpty())
       {
           Toast.makeText(this,"One of more fields is empty",Toast.LENGTH_SHORT).show();
           return;
       }
       // if user name or password doesn't exist in "users" sharedpreferences xml file

       else if(!pref.contains(logUserName) || !logPassword.equals(loggeedUser))
       {
           Toast.makeText(this,"Invalid user name or password ",Toast.LENGTH_SHORT).show();
           return;
       }
       // if proper data
       else
       {
           SharedPreferences.Editor editor=pref.edit();
           editor.putString("Logged",logUserName).commit();
           Toast.makeText(this,"You have successfuly logged",Toast.LENGTH_SHORT).show();
           Intent loggedIntent = new Intent(this, Display_Activity.class);
           // Send  user name to Logged screen
           loggedIntent.putExtra("userPut", pref.getString("Logged", "Error"));
           // Go to logged screen
           this.startActivity(loggedIntent);
       }

   }

_________________________________________________________________________________--
public class RegisterActivity  extends Activity


  {
      EditText UserName;//(EditText)findViewById(R.id.et_user);
      EditText Password1;//=(EditText)findViewById(R.id.et_password);
      EditText Password2;//=(EditText)findViewById(R.id.et_confirm_pass);

      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.register_activity);

         UserName=(EditText)findViewById(R.id.et_user);
         Password1=(EditText)findViewById(R.id.et_password);
         Password2=(EditText)findViewById(R.id.et_confirm_pass);
      }
      public void btnCancel(View v)
      {
          Intent MainIntent=new Intent(this,MainActivity.class);
          // Go to login screen
          this.startActivity(MainIntent);
      }

      public void btnUserRegister(View v)
      {

          SharedPreferences pref=getApplicationContext().getSharedPreferences("users", MODE_PRIVATE);
          SharedPreferences.Editor editor=pref.edit();

          String regUserName=UserName.getText().toString().toLowerCase();
          String regPassword1=Password1.getText().toString();
         String regPassword2=Password2.getText().toString();

          // If any field is empty
          if(regUserName.isEmpty() || regPassword1.isEmpty() || regPassword2.isEmpty())
          {
              Toast.makeText(this, "One of more fields is empty", Toast.LENGTH_SHORT).show();
              return;
          }
          // if user name exist
          else if(pref.contains(regUserName))
          {
              Toast.makeText(this,"User name is exists",Toast.LENGTH_SHORT).show();
              return;
          }
          // if passwords match
          else if(!regPassword1.equals(regPassword2))
          {
              Toast.makeText(this,"Passwords don't match",Toast.LENGTH_SHORT).show();
              return;
          }
          // if proper data
          Toast.makeText(this,"Registration was successful",Toast.LENGTH_SHORT).show();
          // Adding a new user
          editor.putString(regUserName, regPassword1).commit();
          Intent registeredIntent = new Intent(this, MainActivity.class);
          // Go to login screen
          this.startActivity(registeredIntent);

      }


____________________________________________________________________________________

package com.example.ayob.loginsystem;

import android.app.Activity;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.TextView;

/**
 * Created by Ayob on 11/03/2016.
 */
public class Display_Activity  extends Activity

{
    TextView txtUserName;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.user_display);

        txtUserName=(TextView)findViewById(R.id.txt_hello);
        // Print "Hello "+ user name from main activity
        txtUserName.setText("Hello " + getIntent().getStringExtra("userPut"));
    }

    public void btnLogOut(View v)
    {
        SharedPreferences pref=getApplicationContext().getSharedPreferences("users",MODE_PRIVATE);
        SharedPreferences.Editor editor=pref.edit();
        // Remove last logged user
        editor.remove("Logged").commit();
        Intent MainIntent=new Intent(this,MainActivity.class);
        // Go to login screen
        this.startActivity(MainIntent);
    }
}


_____________________________________________________________________________________________________________

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    xmlns:android="http://schemas.android.com/apk/res/android" >
<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal"
    android:layout_weight="1">
    <EditText
        android:layout_height="match_parent"
        android:layout_width="match_parent"
        android:hint="User"
        android:textSize="30sp"
        android:layout_weight="1"
        android:gravity="center"
        android:id="@+id/txt_userName"/>


</LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal"
        android:layout_weight="1"
        android:layout_gravity="center">

        <EditText
            android:layout_height="match_parent"
            android:layout_width="match_parent"
            android:hint="Password"
            android:textSize="30sp"
            android:layout_weight="1"
            android:gravity="center"
            android:id="@+id/txt_Password"/>

    </LinearLayout>
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal"
        android:layout_weight="1"
        android:layout_gravity="center">
  <Button android:layout_height="match_parent"
       android:layout_width="match_parent"
      android:text="Login"
      android:textSize="30dp"
      android:layout_weight="1"
      android:onClick="btnLogin"/>
    </LinearLayout>


<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal"
android:layout_weight="1">
    <Button android:layout_height="match_parent"
        android:layout_width="match_parent"
        android:text="Register"
        android:textSize="30dp"
        android:layout_weight="1"
        android:onClick="btn_show_register"/>
</LinearLayout>
</LinearLayout>

_______________________________________________________________________________________________________________

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    xmlns:android="http://schemas.android.com/apk/res/android" >
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal"
        android:layout_weight="1">
        <EditText
            android:layout_height="match_parent"
            android:layout_width="match_parent"
            android:hint="User"
            android:textSize="30sp"
            android:layout_weight="1"
            android:gravity="center"
            android:id="@+id/et_user"/>


    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal"
        android:layout_weight="1"
        android:layout_gravity="center">

        <EditText
            android:layout_height="match_parent"
            android:layout_width="match_parent"
            android:hint="Password"
            android:textSize="30sp"
            android:layout_weight="1"
            android:gravity="center"
            android:id="@+id/et_password"/>

    </LinearLayout>
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal"
        android:layout_weight="1"
        android:layout_gravity="center">
        <EditText
            android:layout_height="match_parent"
            android:layout_width="match_parent"
            android:hint="confirm password"
            android:textSize="30sp"
            android:layout_weight="1"
            android:gravity="center"
              android:id="@+id/et_confirm_pass"/>
    </LinearLayout>
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal"
        android:layout_weight="1"
        android:layout_gravity="center">
        <Button android:layout_height="match_parent"
            android:layout_width="match_parent"
            android:text="Register"
            android:textSize="30dp"
            android:layout_weight="1"
            android:id="@+id/btn_register"
            android:onClick="btnUserRegister"/>
    </LinearLayout>


    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal"
        android:layout_weight="1">
        <Button android:layout_height="match_parent"
            android:layout_width="match_parent"
            android:text="Cancel"
            android:textSize="30dp"
            android:layout_weight="1"
            android:id="@+id/btn_cancel"
            android:onClick="btnCancel"/>
    </LinearLayout>
</LinearLayout>


__________________________________________________________________________________________________________________



<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    >
    <TextView android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint=""
        android:gravity="center"
        android:textSize="35dp" />


    <TextView android:layout_width="match_parent"

        android:layout_height="wrap_content"
        android:hint="hello user"
        android:gravity="center"
        android:textSize="35dp"
        android:id="@+id/txt_hello"

        />
    <Button
        android:layout_gravity="center"
        android:padding="20dp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="LogOut"
        android:textSize="25dp"
        android:onClick="btnLogOut"/>
    </LinearLayout>