Android Activity Lifecycle With Example & Source Code

Activity Lifecycle:- Activity is one of the building blocks of Android OS. In simple words Activity is a screen that user interact with. Every Activity in android has lifecycle like created, started, resumed, paused, stopped or destroyed. These different states are known as Activity Lifecycle. In other words we can say Activity is a class pre-written in Java Programming.

Below is Activity Lifecycle Decription:--

onCreate() – Called when the activity is first createe

onStart() – Called just after it’s creation or by restart method after onStop(). Here Activity start becoming visible to user

onResume() – Called when Activity is visible to user and user can interact with it

onPause() – Called when Activity content is not visible because user resume previous activity

onStop() – Called when activity is not visible to user because some other activity takes place of it

onRestart() – Called when user comes on screen or resume the activity which was stopped

onDestroy – Called when Activity is not in background

Android Activity Lifecycle Diagram

Generally, in android activity class uses different callback methods like onCreate(), onStart(), onPause(), onRestart(), onResume(), onStop() and onDestroy() to go through a different stages of activity life cycle

Following is the pictorial representation of Android Activity Life cycle which shows how Activity will behave in different stages using callback methods.

Android Activity Lifecycle Example:-

we  are going to create example of lifecycle :

MainActivity.java File Code

package com.example.helloworld;

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.util.Log;

public class MainActivity extends AppCompatActivity {

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        Log.d("Activity Lifecycle","onCreate invoked");

    }

    @Override

    protected void onStart() {

        super.onStart();

        Log.d("Activity Lifecycle","onStart invoked");

    }

    @Override

    protected void onResume() {

        super.onResume();

        Log.d("Activity Lifecycle","onResume invoked");

    }

    @Override

    protected void onPause() {

        super.onPause();

        Log.d("Activity Lifecycle","onPause invoked");

    }

    @Override

    protected void onStop() {

        super.onStop();

        Log.d("Activity Lifecycle","onStop invoked");

    }

    @Override

    protected void onRestart() {

        super.onRestart();

        Log.d("Activity Lifecycle","onRestart invoked");

    }

    @Override

    protected void onDestroy() {

        super.onDestroy();

        Log.d("Activity Lifecycle","onDestroy invoked");

    }

}