Activity Behavior Changes When the Screen Orientation Changes in Android

Introduction

 

This article explains the restart of an Activity device due to orientation changes in Android.

 

Some device configurations change while the application is running, such as when the device changes its orientation. Such a change restarts the activity by calling all its methods again. So when the device orientation changes, first the Activity will disappear for a millisecond when the onPause(), OnStop, and onDestroy() methods are called.

 

After a few milliseconds, the activity will be restarted when the onCreate(), onStart() and onResume() methods are called.

 

Activity LifeCycle

1. onCreate(): This method is called when the Activity is created
2. onStart(): This method is called when the Activity is visible to the user
3. onResume(): This method is called when the Activity starts interacting with the user
4. onPause(): This method is called when the Activity is not visible to the user
5. onStop(): This method is called when the Activity is no longer visible to the user
6. onRestart(): This method is called when the Activity resumes after a stop
7. onDestroy(): This method is called when the Activity is destroyed by the system

So let's see what happens from the start of an activity is created and the activity is destroyed.

 

Step 1

 

Create an Android project like this:

 

 

Step 3

 

Create a Java class file with the following.

 

In this, I have used all the lifecycle methods of an Activity that shows you how the methods are called when the activity creates, destroys and changes its orientation.

package com.example.screenorientation;

import android.os.Bundle;
import android.app.Activity;
import android.util.Log;
import android.view.Menu;

public class MainActivity extends Activity {

    @Override

// onCreate method will be called when the activity is created
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Log.d("cycle","onCreate wiil be invoke");
    }
    @Override

// onStart() method will be called when the activity visible to the user
    protected void onStart() {
        super.onStart();
         Log.d("cycle","onStart wiil be invoked");
    }
    @Override

onResume() method will be called when the activity starts intracting with the user
    protected void onResume() {

        super.onResume();
         Log.d("cycle","onResume wiil be invoked");
    }

 onPause() method will be called when the Activity is not
    @Override

// This method is called when the is not visible to the use
    protected void onPause() {

        super.onPause();
         Log.d("cycle","onPause wiil be invoked");
    }
    @Override

// This methos is called when the Activity is no longer visible to the user
    protected void onStop() {

        super.onStop();
         Log.d("cycle","onStop wiil be invoked");
    }

       @Override

// This method is called when the acvtivity is restarted
    protected void onRestart() {

        super.onRestart();
         Log.d("cycle","onRestart wiil be invoked");
    }
    @Override

This method is called when the activity is destroyed

    protected void onDestroy() {

        super.onDestroy();
         Log.d("cycle","onDestroy wiil be invoked");
    }
}

So when you start the Activity the onCreate(), onStart() and onReume() methods will be called simultaneously.

 

 

After clicking on the back button, first the onPause() method is called then after some time the onStop() and OnDestroy() methods will be called simultaneously.

 

 

Now see what happens when the screen orientation changes.

 

First onPause(), onStop() and onDestroy() will be called simultaneously and after some time when the activity restarts the onCreate(), onStart() and onReume() methods will be called simultaneously.

 

 

So when you change the orientation of a screen the Activity will be restarted.