MY Task

activity_main.xml
=======================
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_margin="16dp"
    android:orientation="vertical">

    <!-- logo -->
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="1"
        android:gravity="center"
        android:orientation="vertical">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="LOGO"
            android:textSize="64dp"
            android:layout_gravity="center"/>

    </LinearLayout>

    <!-- user input -->
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="1"
        android:orientation="vertical"
        android:gravity="center">

        <EditText
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:hint="@string/userName"
            android:inputType="textVisiblePassword|textNoSuggestions"
            android:id="@+id/txtUser"/>

        <EditText
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:hint="@string/userPass"
            android:inputType="textWebPassword"
            android:layout_marginTop="20dp"
            android:id="@+id/txtPass"/>

    </LinearLayout>

    <!-- buttons -->
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="1"
        android:orientation="horizontal"
        android:gravity="top">


        <Button
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:layout_margin="20dp"
            android:text="@string/register"
            android:textColor="#ffffff"
            android:textSize="22sp"
            android:background="#009fff"
            android:id="@+id/btnRegister"
            android:onClick="onClick" />

        <Button
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:layout_margin="20dp"
            android:text="@string/login"
            android:textColor="#ffffff"
            android:textSize="22sp"
            android:background="#009fff"
            android:id="@+id/btnLogin"
            android:onClick="onClick" />

    </LinearLayout>




</LinearLayout>


activity_Register.xml
========================

package com.example.sale7.myapplication3;
import android.content.Context;
import android.content.SharedPreferences;
import android.widget.Toast;

/**
 * Created by teacher on 12/21/2017.
 */

public class UtlUserSP implements UserAble {
    Context context;

    public UtlUserSP() { }

    @Override
    public void setContext(Context context) {
        this.context=context;
    }

    @Override
    public boolean registerUser(String userName, String userPass) {
        //User Exists
        if (userExists(userName)) {
            Toast.makeText(context, "user already exists...", Toast.LENGTH_SHORT).show();
            return false;
        }
        //save user and password

        //declaration of shared preference
        SharedPreferences prefs = context.getSharedPreferences("myPrefs", Context.MODE_PRIVATE);

        //declaration of shared preference editor
        SharedPreferences.Editor editor = prefs.edit();

        //put data inside, we use hash map, so we need KEY,VALUE (k,v)
        editor.putString(userName, userPass);

        //sending data to my shared preferences file.
        editor.commit();
        return true;
    }

    @Override
    public boolean userExists( String userName) {
        //declaration of shared prefernces
        SharedPreferences prefs=context.getSharedPreferences("myPrefs",Context.MODE_PRIVATE);

        //get user pass
        String spPass=prefs.getString(userName,"na");

        //return if users exists, if not (na) return false
        return !spPass.equals("na");
    }

    @Override
    public boolean checkUser( String userName, String userPass) {
        //declaration of shared prefernces
        SharedPreferences prefs=context.getSharedPreferences("myPrefs",Context.MODE_PRIVATE);

        //get user password
        String spPass=prefs.getString(userName,"na");

        //return the result if the passwords are match
        return spPass.equals(userPass);
    }
}

=====================

MainActivity.java
=================
package com.example.sale7.myapplication3;

import android.support.v7.app.AppCompatActivity; // why is it not working well ??
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity { // My TASK PART 1

    final int DefualtName_DB = 11111;
    final String DefualtPassword_DB = "Same";

    EditText txtUser, txtPass;

    @Override
    protected void onCreate(Bundle savedInstanceState) { // "on Create" is the start of the LIFE OF "ACTIVITY"
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        setPointer();
    }

    private void setPointer() {

        txtUser = findViewById(R.id.txtUser); //
        txtPass = findViewById(R.id.txtPass);


    }

    public void OnClick(View view) {

        String userName = txtUser.getText().toString(); // WE RELEATED THE XML PART TO THE JAVA PART
        String userPass = txtPass.getText().toString(); // SAME


        switch (view.getId()) {

            case (R.id.btnLogin):


                if (userName.equals(DefualtName_DB)) {
                    if (userPass.equals(DefualtPassword_DB))

                        Toast.makeText(MainActivity.this, "Login Successfully", Toast.LENGTH_SHORT).show();
                } else if ((!userName.equals(DefualtName_DB)) || (!userPass.equals(DefualtPassword_DB))){

                    Toast.makeText(MainActivity.this, "Inccorect UserName Or Password", Toast.LENGTH_SHORT).show();

                }

                break;


            case (R.id.btnRegister):

                if (userName.length() == 0) {

                    Toast.makeText(MainActivity.this, "InEfficient Input(Name)", Toast.LENGTH_SHORT).show();

                    break;
                }

                if (userPass.length() == 0) {

                    Toast.makeText(MainActivity.this, "InEfficient Input(Pass)", Toast.LENGTH_SHORT).show();

                    break;
                }


                //TODO create a new username <--> md5 password LinkedHashMap

                break;
        }


    }


}

==========
shared prefrences
========
package com.example.sale7.myapplication3;

import android.content.Context;
import android.content.SharedPreferences;

/**
 * Created by teacher on 9/25/2017.
 */

public class SharedPref {

    //for login screen
    public static boolean checkPass(String userName,String userPass, Context context) // CHECKIF PASSWORD EXISTS IS THE SYSTEM.
    {
        //declaration of shared preferences
        SharedPreferences prefs=context.getSharedPreferences("myPrefs",Context.MODE_PRIVATE); // ??
        //get user pass
        String spPass=prefs.getString(userName,"na"); // NA = NOT AVALIABLE
        //check if password matches
        if (userPass.equals(spPass))
        {
            return true;
        }
        return false;
    }

    public static boolean checkUserExists(String userName, Context context) // CHECK IF USER EXISTS IN THE SYSTEM
    {
        //declaration of shared preferences
        SharedPreferences prefs=context.getSharedPreferences("myPrefs",Context.MODE_PRIVATE);
        //get user pass
        String spPass=prefs.getString(userName,"na");
        //check if password matches
        return !spPass.equals("na"); // na = not available
    }

    public static void registerUser(String userName, String userPass, Context context) // WE SET A NEW USER NAME TO THIS CLASS..ALSO WE NEED AN EDITOR TO WRITE IN IT..
    {
        //declaration of shared preferences
        SharedPreferences prefs=context.getSharedPreferences("myPrefs",Context.MODE_PRIVATE);// PUT DATA ISNIDE..SAVE THE CHANGES(comit) AT END.

        //declaration of shared preferences Editor
        SharedPreferences.Editor editor = prefs.edit();

        //put data inside, we use hash map , so we need KEY,VALUE (K,V)
        editor.putString(userName,userPass);

        //sending data to my shared prefernces file, we have to commit the changes
        editor.commit();
    }
}
==========
UtilUserSP
=============
package com.example.sale7.myapplication3;
import android.content.Context;
import android.content.SharedPreferences;
import android.widget.Toast;

/**
 * Created by teacher on 12/21/2017.
 */

public class UtlUserSP implements UserAble {
    Context context;

    public UtlUserSP() { }

    @Override
    public void setContext(Context context) {
        this.context=context;
    }

    @Override
    public boolean registerUser(String userName, String userPass) {
        //User Exists
        if (userExists(userName)) {
            Toast.makeText(context, "user already exists...", Toast.LENGTH_SHORT).show();
            return false;
        }
        //save user and password

        //declaration of shared preference
        SharedPreferences prefs = context.getSharedPreferences("myPrefs", Context.MODE_PRIVATE);

        //declaration of shared preference editor
        SharedPreferences.Editor editor = prefs.edit();

        //put data inside, we use hash map, so we need KEY,VALUE (k,v)
        editor.putString(userName, userPass);

        //sending data to my shared preferences file.
        editor.commit();
        return true;
    }

    @Override
    public boolean userExists( String userName) {
        //declaration of shared prefernces
        SharedPreferences prefs=context.getSharedPreferences("myPrefs",Context.MODE_PRIVATE);

        //get user pass
        String spPass=prefs.getString(userName,"na");

        //return if users exists, if not (na) return false
        return !spPass.equals("na");
    }

    @Override
    public boolean checkUser( String userName, String userPass) {
        //declaration of shared prefernces
        SharedPreferences prefs=context.getSharedPreferences("myPrefs",Context.MODE_PRIVATE);

        //get user password
        String spPass=prefs.getString(userName,"na");

        //return the result if the passwords are match
        return spPass.equals(userPass);
    }
}
========

UserAble InterFace
====
package com.example.sale7.myapplication3;

import android.content.Context;

/**
 * Created by User on 07/01/2018.
 */

public interface UserAble {

    boolean registerUser(String userName, String userPass);
    boolean userExists(String userName);
    boolean checkUser(String userName,String userPass);
    void setContext(Context context);




}
==========
package com.example.sale7.myapplication3;

import android.content.Context;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import com.example.sale7.myapplication3.UtlUserSP;

/**
 * Created by teacher on 12/21/2017.
 */

public class RegisterActivity extends AppCompatActivity {
    Context context;
    EditText regUser,regPass1,regPass2;
    EditText  rName,rpass,rCheck;
    Button btnRegister,btnCancel,rCancel,rRegister;
    UtlUserSP userUtil=new UtlUserSP();

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_register2);
        setPointer();
    }

    private void setPointer() {
        this.context=this;
        userUtil.setContext(context);

        // rName = findViewById(R.id.rUser);


        // rpass = findViewById(R.id.)
        regUser=findViewById(R.id.regUserName);
        regPass1=findViewById(R.id.regPass1);
        regPass2=findViewById(R.id.regPass2);

        btnCancel=findViewById(R.id.btnRegCancel);

        btnCancel.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                finish();
            }
        });


        btnRegister =findViewById(R.id.btnRegRegister);

        btnRegister.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                //CHECK IF PASSWORD O.K
                if (!regPass1.getText().toString().equals(regPass2.getText().toString()))
                {
                    Toast.makeText (context, "Password not match", Toast.LENGTH_SHORT).show();
                    return;
                }
                if (regPass1.getText().toString().length()<3)
                {
                    Toast.makeText(context, "Password must be 3 letter minimum", Toast.LENGTH_SHORT).show();
                    return;
                }
                if(!userUtil.registerUser(regUser.getText().toString(),regPass1.getText().toString()))
                {
                    Toast.makeText(context, "Error in user registration....", Toast.LENGTH_SHORT).show();
                    return;
                }
                Toast.makeText(context, "new user is add...", Toast.LENGTH_SHORT).show();
                finish();
            }
        });

    }
}

=========

Register.java
======
package com.example.sale7.myapplication3;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;

public class Register extends AppCompatActivity implements View.OnClickListener {

    EditText rUser, rPass, rCheck;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_register2);
        setPointer();
    }

    private void setPointer() {
        rUser = (EditText) findViewById(R.id.regUserName);
        rPass = (EditText) findViewById(R.id.regPass1);
        rCheck = (EditText) findViewById(R.id.regPass2);
    }

    @Override
    public void onClick(View view) {
        /*switch (view.getId()) {
            case R.id.rCancel:
                finish();
                break;

            case R.id.rRegister:
                registerUser();
                break;

            default:
                Toast.makeText(this, "Error in buttons", Toast.LENGTH_SHORT).show();
        }*/
    }

    private void registerUser() {
        //check if all fields filled
        if (rUser.getText().toString().isEmpty() ||

                rPass.getText().toString().isEmpty() ||

                rCheck.getText().toString().isEmpty())
        {
            Toast.makeText(this, "Please fill all fields", Toast.LENGTH_LONG).show();
            return;
        }

        //check if minimum password length > 2
        if (rPass.getText().toString().length()<3)
        {
            Toast.makeText(this, "Password is too short (3 minimum)", Toast.LENGTH_SHORT).show();
            return;
        }

        //check if password match
        if (!rPass.getText().toString().equals(rCheck.getText().toString()))
        {
            Toast.makeText(this, "Password not match", Toast.LENGTH_LONG).show();
            return;
        }

        //check if user exists
        if (SharedPref.checkUserExists(rUser.getText().toString(),this))
        {
            Toast.makeText(this, "User already exists", Toast.LENGTH_LONG).show();
            return;
        }

        // AFTER REGISTERATION CHECKOUT THE DATA WILL BE RESTORED IN RTHE DATA BASE
        SharedPref.registerUser(rUser.getText().toString(),rPass.getText().toString(),this);
        finish();
    }
}