MainActivity.java
package com.cfsuman.androidtutorials;
import android.content.Intent;
import android.os.Bundle;
import android.app.Activity;
import android.widget.Button;
import android.widget.TextView;
import java.util.Random;
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Get the widgets reference from XML layout
Button buttonRestart = findViewById(R.id.buttonRestart);
Button buttonRecreate = findViewById(R.id.buttonRecreate);
TextView textView = findViewById(R.id.textView);
// Set the TextView text with a random generated number
textView.setText("Random number : "
+ new Random().nextInt(100));
// Set a click listener for restart Button widget
buttonRestart.setOnClickListener(view -> {
Intent intent = getIntent();
// Finish the activity
finish();
// Restart the activity
startActivity(intent);
});
// Set a click listener for recreate Button widget
buttonRecreate.setOnClickListener(view -> {
// Recreate the activity
recreate();
});
}
}
activity_main.xml
<?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"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:tools="http://schemas.android.com/tools"
android:background="#DCDCDC"
android:padding="24dp">
<Button
android:id="@+id/buttonRestart"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Restart Activity"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:id="@+id/buttonRecreate"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:text="Recreate Activity"
app:layout_constraintBottom_toBottomOf="@+id/buttonRestart"
app:layout_constraintStart_toEndOf="@+id/buttonRestart" />
<TextView
android:id="@+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:fontFamily="sans-serif"
android:textStyle="italic"
android:textSize="24sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/buttonRestart"
tools:text="TextView" />
</androidx.constraintlayout.widget.ConstraintLayout>