lifecycle of Android activity

It's a exercise to understand the lifecycle of a Android activity: onCreate(), onStart(), onRestart(), onResume(), onPause(), onStop(), onDestroy(). Through the exercise, you can note the difference among exit a activity by HOME key, BACK key and finish() call.



main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<TextView  
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="@string/hello"
    />
<TextView
    android:id="@+id/textlife"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:textSize="24px"
    android:text="App first started"
    />
<Button
    android:id="@+id/buttonafterstart"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="Press It!"
    />
<Button
    android:id="@+id/buttonexit"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="EXIT"
    />
</LinearLayout>

AndroidLifeCycle.java

package com.exercise.AndroidLifeCycle;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

public class AndroidLifeCycle extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        Toast.makeText(this, "onCreate()", Toast.LENGTH_LONG).show();
        
        final TextView tvTextLife = (TextView)findViewById(R.id.textlife);
        Button btAfterStart = (Button)findViewById(R.id.buttonafterstart);
        Button btExit = (Button)findViewById(R.id.buttonexit);
        
        btAfterStart.setOnClickListener(new Button.OnClickListener(){

   @Override
   public void onClick(View v) {
    // TODO Auto-generated method stub
    tvTextLife.setText("App started before!");
   }});
        
        btExit.setOnClickListener(new Button.OnClickListener(){

   @Override
   public void onClick(View v) {
    // TODO Auto-generated method stub
    finish();
   }});
    }

 @Override
 protected void onDestroy() {
  // TODO Auto-generated method stub
  super.onDestroy();
  Toast.makeText(this, "onDestroy()", Toast.LENGTH_LONG).show();
 }

 @Override
 protected void onPause() {
  // TODO Auto-generated method stub
  super.onPause();
  Toast.makeText(this, "onPause()", Toast.LENGTH_LONG).show();
 }

 @Override
 protected void onRestart() {
  // TODO Auto-generated method stub
  super.onRestart();
  Toast.makeText(this, "onRestart()", Toast.LENGTH_LONG).show();
 }

 @Override
 protected void onResume() {
  // TODO Auto-generated method stub
  super.onResume();
  Toast.makeText(this, "onResume()", Toast.LENGTH_LONG).show();
 }

 @Override
 protected void onStart() {
  // TODO Auto-generated method stub
  super.onStart();
  Toast.makeText(this, "onStart()", Toast.LENGTH_LONG).show();
 }

 @Override
 protected void onStop() {
  // TODO Auto-generated method stub
  super.onStop();
  Toast.makeText(this, "onStop()", Toast.LENGTH_LONG).show();
 }
    
    
}

Download the files.