Monitoring and processing of return keys in Android apps

Mainactivity:

packagecom.testnbackpressed; 

import android.os.Bundle;  import android.view.KeyEvent;  import android.app.Activity;  /**   * Demo描述:   * 处理Back键按下事件   *    * 注意事项:   * 以下两种方法勿一起使用   */ public class MainActivity  extends Activity {          @Override      protected void onCreate(Bundle savedInstanceState) {           super .onCreate(savedInstanceState);           setContentView(R.layout.main);       }       /**       * 监听Back键按下事件,方法1:       * 注意:       * super.onBackPressed()会自动调用finish()方法,关闭       * 当前Activity.       * 若要屏蔽Back键盘,注释该行代码即可       */      @Override      public void onBackPressed() {           super .onBackPressed();           System.out.println( "按下了back键   onBackPressed()" );              }                    /**      * 监听Back键按下事件,方法2:      * 注意:      * 返回值表示:是否能完全处理该事件      * 在此处返回false,所以会继续传播该事件.      * 在具体项目中此处的返回值视情况而定.      */      @Override      public boolean onKeyDown( int keyCode, KeyEvent event) {           if ((keyCode == KeyEvent.KEYCODE_BACK)) {                System.out.println( "按下了back键   onKeyDown()" );                 return false ;           } else {               return super .onKeyDown(keyCode, event);           }                  }              @Override      protected void onDestroy() {           super .onDestroy();           System.out.println( "执行 onDestroy()" );       }        }Main.xml < RelativeLayout      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"      >          < TextView          android:layout_width = "wrap_content"          android:layout_height = "wrap_content"          android:text = "对于Back键的两种处理方法"          android:layout_centerInParent = "true"          android:textSize = "20sp"     />     </ RelativeLayout >

Monitoring and processing of return keys in Android apps