onCreate() and Other Callback Methods

This section describes activity callback methods: onCreate(), onStart(), onResume(), onPause(), onStop(), onDestroyed(), and onRestart().

As mentioned in the previous section, the lifecycle of an activity has 4 states and 3 lifetime periods. If you want to monitor and adding your own code logics to an activity, you can use the following 7 basic callback methods provided by the android.app.Activity class:

The following diagram shows the 4 states, 3 lifetime periods and 7 callback methods are related:

--------------------------- onCreate() 
   |                           |   (Stopped)
   |                           V
   |   -------------------- onStart() <-- onRestart() <---
   |      |                    |   (Paused)              ^
   |      |                    V                         |
Entire    |   ------------- onResume() <----------       |
Lifetime  |      |             |                 ^       |
   |   Visible   |             |                 |       |
   |   Lifetime  |             |                 |       |
   |      |   Foreground       |   (Active)      |       |
   |      |   Lifetime         |                 |       |
   |      |      |             |                 |       |
   |      |      |             V                 |       |
   |      |   ------------- onPause()            |       |
   |      |                    |   (Paused) ---->|       |
   |      |                    V                         |
   |   -------------------- onStop()                     |
   |                           |   (Stopped) ----------->|
   |                           V
--------------------------- onDestroy()
                                   (Destroyed) 

See next tutorials to implement callback methods.

Last update: 2015.

Table of Contents

 About This Book

 Installing JDK 1.8 on Windows System

 Installation of Android SDK R24 and Emulator

 Installing Apache Ant 1.9 on Windows System

 Developing First Android Application - HelloAndroid

 Android Application Package (APK) Files

 Android Debug Bridge (adb) Tool

 Android File Systems

 Android 4.0.3 File Systems

 AboutAndroid - Application to Retrieve System Information

android.app.Activity Class and Activity Lifecycle

 Introduction of Activity Lifecycle

onCreate() and Other Callback Methods

 ActivityLog - Application to Create Log File

 Viewing Activity Log File with "cat" Command in "adb shell"

 Implementing Activity Callback Methods

 ActivityLog Test - Activity Terminated by User

 ActivityLog Test - Activity Stopped and Restarted

 ActivityLog Test - Activity Paused and Resumed

 View Objects and Layout Resource Files

 Using "adb logcat" Command for Debugging

 Build Process and Package File Content

 Building Your Own Web Browser

 Android Command Line Shell

 Samsung Galaxy Tab 3 Mini Tablet

 USB Debugging Applications on Samsung Tablet

 Android Tablet - LG-V905R

 USB Debugging Applications on LG-V905R Tablet

 Android Phone - LG-P925g

 USB Debugging Applications on LG-P925g Phone

 Outdated Tutorials

 References

 PDF Printing Version