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当片段在选项卡式活动中更改时在片段中运行的双计时器

timer android-fragments android

Ujjwal Jung Thapa · 技术社区 · 6 年前

我在android中实现了一个选项卡式活动。它包含3个片段中的3个标签。在一个片段上我设置了一个倒计时。

我的问题是: 在切换选项卡式活动中的片段并通过tab返回带计时器的片段时, 我的旧计时器值将继续,但计时器值的新实例也将同时运行 即,显示第一个设置的定时器值,然后切换到新的设置的定时器值,然后切换到第一个设置的时间,依此类推。

选项卡式活动与android studio提供的活动相同,对打开片段的更改很小,如下所示:

private SectionsPagerAdapter mSectionsPagerAdapter;

private ViewPager mViewPager;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());

    mViewPager = findViewById(R.id.container);
    mViewPager.setAdapter(mSectionsPagerAdapter);

    TabLayout tabLayout = findViewById(R.id.tabs);

    mViewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
    tabLayout.addOnTabSelectedListener(new TabLayout.ViewPagerOnTabSelectedListener(mViewPager));

}

public class SectionsPagerAdapter extends FragmentPagerAdapter {

    public SectionsPagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public Fragment getItem(int position) {
        Fragment fragment = null;
        switch (position){
            case 0:
                fragment = new FragmentA();
                break;
            case 1:
                fragment = new FragmentB();
                break;
            case 2:
                fragment = new FragmentC();
                break;
        }
        return fragment;
    }

    @Override
    public int getCount() {
        // Show 3 total pages.
        return 3;
    }
}

我用fragmenta实现了倒计时:

public class FragmentA extends Fragment {
TextView mCountDown;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    return inflater.inflate(R.layout.fragment_A, container, false);
}

@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);
    mCountDown = view.findViewById(R.id.tv1);

    new CountDownTimer(100000, 1000) {

        @Override
        public void onTick(long millisUntilFinished) {
            long check = millisUntilFinished;
            int hour = (int) check / (1000 * 60 * 60);
            check = (int) (check - (hour * 1000 * 60 * 60));
            int min = (int) check / (1000 * 60);
            check = (int) (check - (min * 1000 * 60));
            int sec = (int) check / (1000);

            mCountDown.setText(hour + " : " + min + " : " + sec);
        }

        @Override
        public void onFinish() {
            mCountDown.setText("Reached");
        }
    }.start();

}
}

如果有人能帮助我,我会非常感激的。

1 回复 | 直到 6 年前

Ujjwal Jung Thapa 6 年前

好吧,问题出在碎片上。我已经在 onViewCreated()方法 这就产生了问题。

所以解决方案是初始化oncreate()方法的毫秒值,并使用该值启动onviewcreated()方法的倒计时。并且还使用onresume()方法继续相同的计时器,尽管片段是通过选项卡更改的。(为了避免重复代码,还创建了一个计时器的小方法。)

碎片代码:

public class FragmentA extends Fragment {
private long millisecvalue;
TextView mCountDown;
CountDownTimer countDownTimer;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    millisecvalue = 1000000;        //initial timer value
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    return inflater.inflate(R.layout.fragment_A, container, false);
}

@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);


    mCountDown = view.findViewById(R.id.tv1);

    startContinueTimer();

}

private void startContinueTimer() {
    countDownTimer =  new CountDownTimer(millisecvalue, 1000) {

        @Override
        public void onTick(long millisUntilFinished) {
            long check = millisUntilFinished;
            int hour = (int) check / (1000 * 60 * 60);
            check = (int) (check - (hour * 1000 * 60 * 60));
            int min = (int) check / (1000 * 60);
            check = (int) (check - (min * 1000 * 60));
            int sec = (int) check / (1000);

            mCountDown.setText(hour + " : " + min + " : " + sec);
            millisecvalue = millisUntilFinished;    //update milisecvalue "VERY IMPORTANT"
        }

        @Override
        public void onFinish() {
            mCountDown.setText("Reached");
        }
    }.start();
}

@Override
public void onResume() {
    super.onResume();
    startContinueTimer();
}
}

希望这有帮助。如果有更好的方法,请告诉我!