从设备的后退按钮开始操作

Question

当用户从他的设备上按下后退按钮时我想要一个动作。我能做到吗？谢谢

Answer 1

Here是用户按下后退按钮时如何实现功能的一些示例

Answer 2

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    if ((keyCode == KeyEvent.KEYCODE_BACK)) {
        Log.d(this.getClass().getName(), "back button pressed");
        if(canPressBack) {
            return super.onKeyDown(keyCode, event);
        }
    }
    return true;
}

Answer 3

活动有public void onBackPressed()回调方法..使用它

Answer 4

试试此代码

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    String dialog_message = "Please Select at least one item or press Cancel button";
    if(keyCode==KeyEvent.KEYCODE_BACK)
    {
         AlertDialog.Builder invalid_input_dialog = new AlertDialog.Builder(Classname.this);
          invalid_input_dialog.setTitle("Application name")
          .setMessage(dialog_message)
          .setCancelable(true)
          .setPositiveButton("Ok", new DialogInterface.OnClickListener(){
              @Override
                public void onClick(DialogInterface dialog, int which) {

              }
          })
          .show();
        return true;
    }
    return super.onKeyDown(keyCode, event);
}