AndroidアプリケーションにおけるBackキーの傍受および処理例

MainActivityは次のとおりです.

 
  
package cn.testnbackpressed; 
  
import android.os.Bundle; 
  
import android.view.KeyEvent; 
  
import android.app.Activity; 
  
/** 
  
* Demo  : 
  
*   Back      
  
* 
  
*     : 
  
*             
  
*/ 
  
public class MainActivity extends Activity { 
  
@Override 
  
protected void onCreate(Bundle savedInstanceState) { 
  
super.onCreate(savedInstanceState); 
  
setContentView(R.layout.main); 
  
} 
  
/** 
  
*   Back     ,  1: 
  
*   : 
  
* super.onBackPressed()     finish()  ,   
  
*   Activity. 
  
*     Back  ,         
  
*/ 
  
@Override 
  
public void onBackPressed() { 
  
super.onBackPressed(); 
  
System.out.println("   back  onBackPressed()"); 
  
} 
  
/** 
  
*   Back     ,  2: 
  
*   : 
  
*      :           
  
*      false,          . 
  
*                  . 
  
*/ 
  
@Override 
  
public boolean onKeyDown(int keyCode, KeyEvent event) { 
  
if ((keyCode == KeyEvent.KEYCODE_BACK)) { 
  
System.out.println("   back  onKeyDown()"); 
  
return false; 
  
}else { 
  
return super.onKeyDown(keyCode, event); 
  
} 
  
 
  
} 
  
 
  
@Override 
  
protected void onDestroy() { 
  
super.onDestroy(); 
  
System.out.println("   onDestroy()"); 
  
} 
  
} 
  
 
 

main.xmlは次のとおりです.

 
  
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" 
  
> 
  
android:layout_width="wrap_content" 
  
android:layout_height="wrap_content" 
  
android:text="  Back        " 
  
android:layout_centerInParent="true" 
  
android:textSize="20sp" 
  
/>