@Overridepublic void onCreate(Bundle savedInstanceState) {  super.onCreate(savedInstanceState);  setContentView(R.layout.main); } protected void dialog() {  AlertDialog.Builder builder = new Builder(HanderTestActivty.this);  builder.setMessage("確定要退出嗎?");  builder.setTitle("提示");  builder.setPositiveButton("確認(rèn)",   new android.content.DialogInterface.OnClickListener() {    @Override   public void onClick(DialogInterface dialog, int which) {    dialog.dismiss();    HanderTestActivty.this.finish();    }   });  builder.setNegativeButton("取消",   new android.content.DialogInterface.OnClickListener() {    @Override   public void onClick(DialogInterface dialog, int which) {    dialog.dismiss();    }   });  builder.create().show(); } @Overridepublic boolean onKeyDown(int keyCode, KeyEvent event) {  if (keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0) {   dialog();   return false;  }  return false; }