Code of MainActivity.java to display LogIn Screen

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button button = (Button) findViewById(R.id.login);
        final EditText et1 = (EditText) findViewById(R.id.txtname);
        final EditText et2 = (EditText) findViewById(R.id.txtpassword);
        button.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {

                if((et1.getText().toString().trim().equals("admin"))&& (et2.getText().toString().trim().equals("admin"))) {
                    Intent intent = new Intent(MainActivity.this, MainActivity2.class);

                    String message = et1.getText().toString();
                    intent.putExtra("myname", message);
                    startActivity(intent);

                }
                else if((et1.getText().toString().trim().equals(""))&& (et2.getText().toString().trim().equals("")))
                {
                    final AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
                    builder.setTitle("W3TechBlog Community");
                    builder.setMessage("Enter Username or Password").setPositiveButton("OK", new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int id) {

                        }
                    });

                    builder.setIcon(R.drawable.ic_launcher_foreground);
                    AlertDialog dialog = builder.create();
                    dialog.show();
                }
                else
                {
                    final AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
                    builder.setTitle("W3TechBlog Community");
                    builder.setMessage("Wrong Username or Password").setPositiveButton("OK", new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int id) {

                        }
                    });

                    builder.setIcon(R.drawable.ic_launcher_foreground);
                    AlertDialog dialog = builder.create();
                    dialog.show();
                }

            }
        });
    }
                               

Code of MainActivity.java to display Welcome Message

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main3);
        final TextView et1 = (TextView) findViewById(R.id.mymessage);
        Intent intent = getIntent();
        String message = intent.getStringExtra("myname");

        et1.setText("Welcome : "+message);
    } 

Code of activity_main.xml for LogIn Screen

<?xml version="1.0" encoding="utf-8"?>


<ScrollView android:layout_height="match_parent" android:layout_width="match_parent"
    xmlns:android="http://schemas.android.com/apk/res/android">
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        tools:context=".MainActivity">

    <TextView
        android:id="@+id/textView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Enter Username"
        android:textAlignment="center"
        android:textAppearance="@style/TextAppearance.AppCompat.Body2"
        android:layout_marginTop="20dp"
        android:textSize="25sp"
        android:textColor="@android:color/holo_blue_light" />

    <EditText
        android:id="@+id/txtname"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="20"
        android:hint="Enter Name"
        android:layout_marginLeft="40dp"
        android:layout_marginRight="40dp"
        android:layout_marginTop="10dp"
        android:inputType="textPersonName"
        />
    <TextView
        android:id="@+id/textView1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Enter Password"
        android:textAlignment="center"
        android:textAppearance="@style/TextAppearance.AppCompat.Body2"
        android:layout_marginTop="30dp"
        android:textSize="25sp"
        android:textColor="@android:color/holo_blue_light"
        />

    <EditText
        android:id="@+id/txtpassword"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="20"
        android:hint="Enter Password"
        android:inputType="textPassword"
        android:layout_marginLeft="40dp"
        android:layout_marginRight="40dp"
        android:layout_marginTop="10dp"
        />

    <Button
        android:id="@+id/login"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="LogIn"
        android:layout_marginTop="40dp"
        android:textSize="25sp"
        android:textColor="@android:color/white"
        android:background="@color/colorAccent"
        android:layout_marginLeft="40dp"
        android:layout_marginRight="40dp"
        android:layout_marginBottom="70dp"
        />
    </LinearLayout>
    </ScrollView>

Code of activity_main.xml for Welcome Message

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity2">

    <TextView
        android:id="@+id/mymessage"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Welcome"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        android:textSize="25sp"
        android:textColor="@color/design_default_color_error"
        />
</androidx.constraintlayout.widget.ConstraintLayout>

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