抽象類方法-倒計時顯示（二）

這是托馬斯寫的一個關於封裝倒計時的 

package test.hatainet.com.firstgradletest;

import android.app.Fragment;
import android.os.Handler;
import android.os.Looper;

/**
 * Created by Thomas on 2017/12/5.
 */

public abstract class FragmentWithTimer extends Fragment
{
    public static final int TIME_GAP = 100;
    public static final int TIME_RANGE = 60000;
    private int flag;
    private long timeflag;

    public void startCountDown()
    {
        timeflag = System.currentTimeMillis();
        flag = (int) Math.random() * Integer.MAX_VALUE;
        final int THIS_FLAG = flag;
        new Handler(Looper.getMainLooper()).postDelayed(new Runnable()
        {
            @Override
            public void run()
            {
                coundDown(THIS_FLAG);
            }
        }, TIME_GAP);

    }

    private void coundDown(final int THIS_FLAG)
    {
        if (flag != THIS_FLAG) {return;}
        int timepassed = (int) ((System.currentTimeMillis() - timeflag) / 1000);
        onTimeTextChange(timepassed);
        if (System.currentTimeMillis() - timeflag < TIME_RANGE)
        {
            new Handler(Looper.getMainLooper()).postDelayed(new Runnable()
            {
                @Override
                public void run()
                {
                    coundDown(THIS_FLAG);
                }
            }, TIME_GAP);
        }
    }

    public abstract void onTimeTextChange(int timepassed);

    public void resetCountDownTime()
    {
        timeflag = System.currentTimeMillis();
    }
}