实现处理程序的基本方法

Question

好的,所以我已经阅读了许多关于处理程序的教程和线程,但是他们似乎对我自己的处理程序知识更加先进,这是我第一次使用处理程序这么光顾我.我在处理程序上有这个示例应用程序,它在某个时间触发Log,但是当我点击我的开始按钮时它似乎无法正常工作.以下是我的代码.

public class Main extends Activity {
    private long selectedTimeInMills;
    private Handler handler;
    private static final Calendar CALENDAR = Calendar.getInstance();
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        TimePicker timepicker = (TimePicker) findViewById(R.id.timePicker1);
        final TextView timeText = (TextView) findViewById(R.id.time);

        Button start = (Button) findViewById(R.id.button1);
        handler = new Handler();
        String textTime = formatDate(CALENDAR.getTimeInMillis(), "hh:mm a");
        timeText.setText(textTime);

        timepicker.setOnTimeChangedListener(new OnTimeChangedListener() {

            public void onTimeChanged(TimePicker view, int hourOfDay, int minute) {
                CALENDAR.set(Calendar.HOUR_OF_DAY, hourOfDay);
                CALENDAR.set(Calendar.MINUTE, minute);
                selectedTimeInMills = CALENDAR.getTimeInMillis();
                String textTime = formatDate(CALENDAR.getTimeInMillis(), "hh:mm a");
                timeText.setText(textTime);
            }
        });

        start.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {
                Runnable runnable =  new Runnable() {

                    public void run() {
                        Log.d("HandlerCheck", "Handler Fired! @ ("+selectedTimeInMills+") "+formatDate(selectedTimeInMills, "hh:mm a"));
                    }
                };
                boolean flag = handler.postAtTime(runnable, selectedTimeInMills);

                Toast.makeText(Main.this, "Handler is Fired?:: "+flag, Toast.LENGTH_LONG).show();
            }


        });

    }
}

注意:当我点击我的按钮并实现handler.postAtTime()它返回true但仍然不会显示登录DDMS即使我已经设置我的时间戳从当前时间1分钟仍然不会触发DDMS上的日志消息

Answer 1

postAtTimeHandler类中的方法接受来自statup的时间,以毫秒为单位; 不是Calendar时间(这是你要经过的).你应该SystemClock.uptimeMillis()用来计算时间.

或者,您可以使用postDelayed函数在设置的时间段(以毫秒为单位)后调用Runnable对象.

// Introduce a new private variable
private long delayedTimeInMillis;

// Update delayedTimeInMillis inside onTimeChanged method:
delayedTimeInMillis = selectedTimeInMills - Calendar.getInstance().getTimeInMillis();

// replace handler.postAtTime(runnable, selectedTimeInMills); line with this:
handler.postDelayed(runnable, delayedTimeInMillis)