Activity Lifecycle in Android with Source code.

• Android Activity Lifecycle is controlled by 7 methods of android.app.Activity class. 
• The android Activity is the subclass of Context Theme Wrapper class.

Method	Description
onCreate	called when activity is first created.
onStart	called when activity is becoming visible to the user.
onResume	called when activity will start interacting with the user.
onPause	called when activity is not visible to the user.
onStop	called when activity is no longer visible to the user.
onRestart	called after your activity is stopped, prior to start.
onDestroy	called before the activity is destroyed.

EXAMPLE :-

activity_mail.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=".MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Android Life Cycle Program!"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</android.support.constraint.ConstraintLayout>

MainActivity.java

package com.example.sunny.lifecycle;

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

public class MainActivity extends AppCompatActivity {

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

        Toast.makeText(getApplicationContext(),"onCreate Method Call",
                Toast.LENGTH_LONG).show();

}

protected void onStart()
        {
            super.onStart();
            
            Toast.makeText(getApplicationContext(),"onStart Method Call",
                    Toast.LENGTH_LONG).show();

        }

@Override
protected void onRestart()
        {
        super.onRestart();
            Toast.makeText(getApplicationContext(),"onRestart Method Call",
                    Toast.LENGTH_LONG).show();

        }

protected void onPause()
        {
        super.onPause();
            Toast.makeText(getApplicationContext(),"onPause Method Call",
                    Toast.LENGTH_LONG).show();

        }

protected void onResume()
        {
        super.onResume();
            Toast.makeText(getApplicationContext(),"onResume Method Call",
                    Toast.LENGTH_LONG).show();

        }

protected void onStop()
        {
        super.onStop();
           
            Toast.makeText(getApplicationContext(),"onStop Method Call",
                    Toast.LENGTH_LONG).show();

        }

protected void onDestroy()
        {
        super.onDestroy();
            Toast.makeText(getApplicationContext(),"onDestroy Method Call",
                    Toast.LENGTH_LONG).show();

        }
 }

OUTPUT