Activities Life Cycle in Android

Introduction

 

An Activity is a sub-container within an application container that describes all the UI controls.

 

Every Container has a life cycle (methods) that determine the phase's Activity.

 

To create an Activity in Android we have to extend the Activity class.

 

How to work with an Activity?

 

An Image view of an Activity's life cycle:

 

 

The following is the source code.

 

MainActivity.java

package com.Saving.savingactivity;
import android.os.Bundle;
import android.app.Activity;
//import android.view.Menu;
import android.widget.Toast;
public class MainActivity extends Activity {
      @Override
      protected void onRestoreInstanceState(Bundle savedInstanceState) {
            super.onRestoreInstanceState(savedInstanceState);
            Toast.makeText(getBaseContext(), "Restored ", Toast.LENGTH_LONG).show();
      };
      @Override
      protected void onStart() {
            // TODO Auto-generated method stub
            super.onStart();
            Toast.makeText(getBaseContext(), "Started ", Toast.LENGTH_LONG).show();
      }
      @Override
      protected void onResume() {
            // TODO Auto-generated method stub
            super.onResume();
            Toast.makeText(getBaseContext(), "Resumed ", Toast.LENGTH_LONG).show();
      }
      @Override
      protected void onPause() {
            // TODO Auto-generated method stub
            super.onPause();
            Toast.makeText(getApplicationContext(), "Paused ", Toast.LENGTH_LONG).show();
      }
      @Override
      protected void onSaveInstanceState(Bundle outState) {
            // TODO Auto-generated method stub
            super.onSaveInstanceState(outState);
            Toast.makeText(getApplicationContext(), "Saved ", Toast.LENGTH_LONG).show();
      }
      @Override
      protected void onStop() {
            // TODO Auto-generated method stub
            super.onStop();
            Toast.makeText(getApplicationContext(), "Stoped ", Toast.LENGTH_LONG).show();
      }
      @Override
      protected void onDestroy() {
            // TODO Auto-generated method stub
            super.onDestroy();
            Toast.makeText(getApplicationContext(),"Destroy ", Toast.LENGTH_LONG).show();
      }
}

Activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity"
    android:layout_centerHorizontal="true"
     android:layout_centerVertical="true">
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/hello_world" />
</LinearLayout>

Step 1

 

First of all, an Activity is creates on a pre-defined Layout by the "onCreate" method.

 

Step 2

 

 After that, the Activity will start in the "onStart" method.

 

 

Step 3

 

After starting the "onResume" method displays your current UI.

 

 

Step 4

 

After "onResume" if we kill or auto kills the UI then the UI calls the "onPause" method.

 

 

Step 5

 

After "onPause" for the current UI, the UI call goes to the "onSave" method.

 

 

Step 6

 

The "onSave" method may be called after "onPause" or "onStop"; it depends on the condition in which the UI is killed.

 

 

Step 7

 

If we kill the process or active UI then that goes directly to destroy (without saving the current UI ) by the "onDestroy" method.

 

Otherwise, it goes to "onStop" (step 4).