我正在尝试使用闹钟管理器在特定时间设置闹钟，但闹钟立即被启动了？

这是我的onclick()函数，它将设置目标闹钟。

      SA=(Button)findViewById(R.id.button1);
      SA.setOnClickListener(new OnClickListener() {
        @SuppressWarnings(\"deprecation\")
        @Override
            public void onClick(View v) {
                showDialog(id);
            }
        });
    }
        @Override
        protected Dialog onCreateDialog(int id1) {
        switch (id1) {
        case id:
            //将时间选择器设置为当前时间
            return new TimePickerDialog(this, 
                                         timePickerListener, hour, min,false);
        }
        return null;
    }
        private TimePickerDialog.OnTimeSetListener timePickerListener = 
            new TimePickerDialog.OnTimeSetListener() {
        public void onTimeSet(TimePicker view, int selectedHour,
                int selectedMinute) {
            Calendar calnow=Calendar.getInstance();
            calnow.setTimeInMillis(System.currentTimeMillis());
            calnow.set(Calendar.HOUR_OF_DAY,selectedHour);
            calnow.set(Calendar.MINUTE,selectedMinute);
            calnow.set(Calendar.SECOND, 0);
             Intent intent=new Intent(getBaseContext(),alarm.class); 
            PendingIntent pendingintent= PendingIntent.getBroadcast(getBaseContext(),0,       intent, 0);
             AlarmManager alarmManager =     (AlarmManager)getSystemService(Context.ALARM_SERVICE);
              alarmManager.set(AlarmManager.RTC_WAKEUP,  calnow.getTimeInMillis(),pendingintent);
              Toast.makeText(getBaseContext(), \"闹钟已设置\", Toast.LENGTH_SHORT).show();
        }
    };

    public void onReceive(Context arg0, Intent arg1) {
         AlarmManager mgr = (AlarmManager)arg0.getSystemService(Context.ALARM_SERVICE);
            Toast.makeText(arg0,\"闹钟已启动.....\", Toast.LENGTH_LONG).show();

问题在于，我在点击按钮设置闹钟之前就会收到“闹钟已设置”和“闹钟已启动”的两个提示。