Example
Assume an application with a MainActivity which can call the Next Activity using a button click.
public class MainActivity extends AppCompatActivity {
private final String LOG_TAG = MainActivity.class.getSimpleName();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Log.d(LOG_TAG, "calling onCreate from MainActivity");
}
@Override
protected void onStart() {
super.onStart();
Log.d(LOG_TAG, "calling onStart from MainActivity");
}
@Override
protected void onResume() {
super.onResume();
Log.d(LOG_TAG, "calling onResume from MainActivity");
}
@Override
protected void onPause() {
super.onPause();
Log.d(LOG_TAG, "calling onPause from MainActivity");
}
@Override
protected void onStop() {
super.onStop();
Log.d(LOG_TAG, "calling onStop from MainActivity");
}
@Override
protected void onDestroy() {
super.onDestroy();
Log.d(LOG_TAG, "calling onDestroy from MainActivity");
}
@Override
protected void onRestart() {
super.onRestart();
Log.d(LOG_TAG, "calling onRestart from MainActivity");
}
public void toNextActivity(){
Log.d(LOG_TAG, "calling Next Activity");
Intent intent = new Intent(this, NextActivity.class);
startActivity(intent);
} }
and
public class NextActivity extends AppCompatActivity {
private final String LOG_TAG = NextActivity.class.getSimpleName();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_next);
Log.d(LOG_TAG, "calling onCreate from Next Activity");
}
@Override
protected void onStart() {
super.onStart();
Log.d(LOG_TAG, "calling onStart from Next Activity");
}
@Override
protected void onResume() {
super.onResume();
Log.d(LOG_TAG, "calling onResume from Next Activity");
}
@Override
protected void onPause() {
super.onPause();
Log.d(LOG_TAG, "calling onPause from Next Activity");
}
@Override
protected void onStop() {
super.onStop();
Log.d(LOG_TAG, "calling onStop from Next Activity");
}
@Override
protected void onDestroy() {
super.onDestroy();
Log.d(LOG_TAG, "calling onDestroy from Next Activity");
}
@Override
protected void onRestart() {
super.onRestart();
Log.d(LOG_TAG, "calling onRestart from Next Activity");
} }
When app is first created
D/MainActivity: calling onCreate from MainActivity
D/MainActivity: calling onStart from MainActivity
D/MainActivity: calling onResume from MainActivity
are called
When screen sleeps
08:11:03.142 D/MainActivity: calling onPause from MainActivity
08:11:03.192 D/MainActivity: calling onStop from MainActivity
are called. And again when it wakes up
08:11:55.922 D/MainActivity: calling onRestart from MainActivity
08:11:55.962 D/MainActivity: calling onStart from MainActivity
08:11:55.962 D/MainActivity: calling onResume from MainActivity
are called
Case1:
When Next Activity is called from Main Activity
D/MainActivity: calling Next Activity
D/MainActivity: calling onPause from MainActivity
D/NextActivity: calling onCreate from Next Activity
D/NextActivity: calling onStart from Next Activity
D/NextActivity: calling onResume from Next Activity
D/MainActivity: calling onStop from MainActivity
When Returning back to the Main Activity from Next Activity using back button
D/NextActivity: calling onPause from Next Activity
D/MainActivity: calling onRestart from MainActivity
D/MainActivity: calling onStart from MainActivity
D/MainActivity: calling onResume from MainActivity
D/NextActivity: calling onStop from Next Activity
D/NextActivity: calling onDestroy from Next Activity
Case2:
When Activity is partially obscured (When overview button is pressed) or When app goes to background and another app completely obscures it
D/MainActivity: calling onPause from MainActivity
D/MainActivity: calling onStop from MainActivity
and when the app is back in the foreground ready to accept User inputs,
D/MainActivity: calling onRestart from MainActivity
D/MainActivity: calling onStart from MainActivity
D/MainActivity: calling onResume from MainActivity
are called
Case3:
When an activity is called to fulfill implicit intent and user has make a selection. For eg., when share button is pressed and user has to select an app from the list of applications shown
D/MainActivity: calling onPause from MainActivity
The activity is visible but not active now. When the selection is done and app is active
D/MainActivity: calling onResume from MainActivity
is called
Case4:
When the app is killed in the background(to free resources for another foreground app), onPause(for pre-honeycomb device) or onStop(for since honeycomb device) will be the last to be called before the app is terminated.
onCreate and onDestroy will be called utmost once each time the application is run. But the onPause, onStop, onRestart, onStart, onResume maybe called many times during the lifecycle.
