Android中Toast不能显示的问题

我想展示一个toast消息, 但不知为什么它总是不能被调用时,以下是我的oncreate代码：

public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            this.requestWindowFeature(Window.FEATURE_NO_TITLE);
            this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                    WindowManager.LayoutParams.FLAG_FULLSCREEN);
            setContentView(R.layout.alarm);

            mediaPlayer = MediaPlayer.create(getApplicationContext(),
                    R.raw.alarmclock);
            mediaPlayer.start();

            Toast.makeText(this, "Alarm time up", Toast.LENGTH_LONG);
    }

在使用makeText()后要调用show()来显示你的信息:

Toast.makeText(this, "Alarm time up", Toast.LENGTH_LONG).show();

你丢了这句代码了：

Toast.makeText(your_activity.this, "u clicked me", Toast.LENGTH_SHORT).show();

要调用 show()