手機返回鍵監聽

//返回鍵監聽
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    if (keyCode == KeyEvent.KEYCODE_BACK) {
        AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
        builder.setIcon(R.mipmap.ic_launcher);

        builder.setTitle("退出程序");
        builder.setMessage("主人真的要退出嗎?再考慮考慮....");
        builder.setNegativeButton("殘忍退出", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                finish();
            }
        });
        builder.setPositiveButton("再玩一會", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                dialog.dismiss();
                Toast.makeText(MainActivity.this, "謝謝您喜歡咱們的產品", Toast.LENGTH_SHORT).show();
            }
        });
        builder.create();
        builder.show();


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