当他们对用户可见时，在查看寻呼机上更新片段

Question

我有50个页面，需要不断更新当前片段，ChangeListener工作正常，但是第一次刷新不起作用，当它变为可见时如何实现片段刷新用户？

MyPagerAdapter adapter = new MyPagerAdapter(getChildFragmentManager(), data); 
mViewPager.setAdapter(adapter); 
int position = data.size() - 1; 
adapter.getFragment(position).refresh(); 
mViewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() { 
    @Override 
    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {} 

    @Override 
    public void onPageSelected(int position) { 
     adapter.getFragment(position).refresh(); 
    } 

    @Override 
    public void onPageScrollStateChanged(int state) {} 
}); 

PageAdapter

private class MyPagerAdapter extends FragmentStatePagerAdapter { 

    private final List<DateTime> mData; 
    private Map<Integer, PagerFragment> mMap = new HashMap<>(); 

    public MyPagerAdapter(FragmentManager fm, List<DateTime> data) { 
     super(fm); 
     mData = data; 
    } 

    @Override 
    public Fragment getItem(int position) { 
     return PagerFragment.newInstance(mData.get(position)); 
    } 

    @Override 
    public Object instantiateItem(ViewGroup container, int position) { 
     PagerFragment f = (PagerFragment) super.instantiateItem(container, position); 
     mMap.put(position, f); 
     return f; 
    } 

    @Override 
    public void destroyItem(ViewGroup container, int position, Object object) { 
     super.destroyItem(container, position, object); 
     mMap.remove(position); 
    } 

    @Override 
    public int getCount() { 
     return mData.size(); 
    } 

    public PagerFragment getFragment(int position) { 
     return mMap.get(position); 
    } 
} 

Answer 1

的第一问是不是正确的，我需要“当他们站在可见的用户更新分段上查看传呼机”，我找到了答案：

编辑：

public abstract class PageFragment extends Fragment { 

protected Boolean mVisibleToUserFlag = null; 

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

    if (mVisibleToUserFlag != null && mVisibleToUserFlag) { 
     onVisible(); 
    } 
} 

@Override 
public void setUserVisibleHint(boolean isVisibleToUser) { 
    super.setUserVisibleHint(isVisibleToUser); 

    if (isVisibleToUser && (mVisibleToUserFlag == null || mVisibleToUserFlag == false)) { 
     mVisibleToUserFlag = true; 
     if (isResumed()) { 
      onVisible(); 
     } 
    } else if (!isVisibleToUser && mVisibleToUserFlag == null) { 
     mVisibleToUserFlag = false; 
    } else if (!isVisibleToUser && mVisibleToUserFlag) { 
     onHide(); 
     mVisibleToUserFlag = false; 
    } 
} 

@Override 
public void onDestroyView() { 
    super.onDestroyView(); 

    mVisibleToUserFlag = null; 
} 

/** 
* This method invoked when page stand visible to user. 
*/ 
public abstract void onVisible(); 

/** 
* This method invoked then page change state visibility change to hidden. 
*/ 
public abstract void onHide(); 

}