Create an android app that demonstrates Activity Lifecycle and Instance State.

In this tutorial we will see the working of Activity lifecycle step by step. Activity  life cycle consists of 7 methods as below.

1. onCreate() -   Invoked when Activity is created.
2. onStart() -      Invoked when Activity is becoming visible.
3. onResume() - Invoked when Activity starts Interacting with user.
4. onPause() -    Invoked when Activity is invisible to user
5. onStop() -       Invoked when activity is no longer visible.
6. onRestart() -  Invoked after your activity is stopped, prior to start.
7. onDestroy() - Invoked  before Activity is killed.

Let's begin coding....💻💻

Step 1: After creating Android project, open activity_main.xml file and paste below code as it is.

activity_main.xml

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

<android.support.constraint.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="example.javatpoint.com.activitylifecycle.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>

Step 2: Now open MainActivity.java file and paste below code.

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.widget.Toast;

public class MainActivity extends Activity
{
    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toast.makeText(MainActivity.this,"onCreate invoked",Toast.LENGTH_SHORT).show();

        Log.d("lifecycle","onCreate invoked");
    }

    @Override

    protected void onStart()
    {
        super.onStart();
        Toast.makeText(MainActivity.this,"onStart invoked",Toast.LENGTH_SHORT).show();

        Log.d("lifecycle","onStart invoked");
    }

    @Override
    protected void onResume() 

    {
        super.onResume();
        Toast.makeText(MainActivity.this,"onResume invoked",Toast.LENGTH_SHORT).show();

        Log.d("lifecycle","onResume invoked");
    }

    @Override
    protected void onPause()
    {
        super.onPause();
        Toast.makeText(MainActivity.this,"onPause invoked",Toast.LENGTH_SHORT).show();

        Log.d("lifecycle","onPause invoked");
    }

    @Override
    protected void onStop()
    {
        super.onStop();
        Toast.makeText(MainActivity.this,"onStop invoked",Toast.LENGTH_SHORT).show();

        Log.d("lifecycle","onStop invoked");
    }

    @Override
    protected void onRestart()
    {
        super.onRestart();
        Toast.makeText(MainActivity.this,"onRestart invoked",Toast.LENGTH_SHORT).show();

        Log.d("lifecycle","onRestart invoked");
    }

    @Override
    protected void onDestroy()
    {
        super.onDestroy();
        Toast.makeText(MainActivity.this,"onDestroy invoked",Toast.LENGTH_SHORT).show();

        Log.d("lifecycle","onDestroy invoked");
    }

}

Step 3: wohoo!! we are done with the coding in just two steps. Now run the project and see output in Logcat.

Note: Logcat is located at the bottom of the Android Studio.

Enjoy coding!!!🙌