Question

我尝试覆盖 onkeydown（）方法以及 onBackPressed（）方法但是警告对话框不会显示而是只返回到以前的意图。我尝试了几个例子，但没有一个有效。

 @Override
     public boolean onKeyDown(int keyCode, KeyEvent event) {
          if (keyCode == KeyEvent.KEYCODE_BACK) {
        onBackPressed();

      }

      return super.onKeyDown(keyCode, event);
   }

      @Override
       public void onBackPressed() {


       Log.d("confirm save method","");
        AlertDialog.Builder builder = new AlertDialog.Builder(this);

           builder.setTitle("");
           builder.setMessage("Do you want to Save the Game ?");
           builder.setCancelable(false);
               builder.setPositiveButton("YES",
                 new DialogInterface.OnClickListener() {
                       public void onClick(DialogInterface dialog, int which) {
                    finish();
                    System.exit(0);
                }
            });

    builder.setNegativeButton("NO",
            new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int which) {
                    dialog.cancel();
                }
            });

               AlertDialog alert = builder.create();
              alert.show();


            Log.d("confirm save method","");

}

Answer 1

提示1：如果您覆盖onBackPressed，则不必覆盖onKeyDown(int keyCode, KeyEvent event)。这很复杂。删除此方法（onKeyDown）可以解决此问题。

提示2：return true来中断此关键事件。

 @Override
 public boolean onKeyDown(int keyCode, KeyEvent event) {
      if (keyCode == KeyEvent.KEYCODE_BACK) {
      alertAialog();
      return true;
      }

  return super.onKeyDown(keyCode, event);
}
private void alertDialog(){
 ...
}

Answer 2

@Override
public void onBackPressed() {
    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setMessage("Are you sure you want to exit?")
            .setTitle("Exit Alert")
            .setCancelable(false)
            .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int id) {

                    //finishAffinity(); 
                    finish();  //or do anything
                }
            })
            .setNegativeButton("No", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int id) {
                    dialog.cancel();
                }
            });
    AlertDialog alert = builder.create();
    alert.show();
}

尝试此代码，并删除onKeyDown（）;

OnBackPressed不显示警报

2 个答案: