Question

我有一个ViewPager，我使用FragmentStatePagerAdapter填充片段（表示来自arrayListOfObjects的对象）。一切运作良好：

            mMyFragmentPagerAdapter = new fragmentAdapter(getSupportFragmentManager(),orientation
            ,rePopulatedfireInfoList);
        mPager = (ViewPager)findViewById(R.id.fireInfoFragment_container);
        initButton();
        setTab();
        mPager.setAdapter(mMyFragmentPagerAdapter);

片段适配器扩展了FragmentStatePagerAdapter。

从主要活动开始，我发起一个对话主题活动;用户可以添加新的收藏位置，创建一个新对象，改变主要活动传递的对象的arraylist。这是启动对话活动的代码;一切正常：

        Intent locationIntent = new Intent(afisController.this, locationActivity.class);
    locationIntent.putExtra("firesList", new fireInfoListWrapper(arrayListOfObjects));
    startActivityForResult(locationIntent,1);

浮动活动将对象添加到arrayListOfObjects中。

在主要活动的onActivityResult上，我将我收到的arraListOfObjects与我发送的那个进行比较;如果不同，我想完全删除viewPager的内容并使用新的arrayListOfObjects重新创建它。这是onActivityResults：

     protected void onActivityResult(int requestCode, int resultCode,
            Intent data) {
 Toast.makeText(this, "Activity Results fired..." , 1500 ).show();
            if ((resultCode == 0) && (data != null)) { 
                Log.i("onActvityResult", "Inside resultCode check");   
                Bundle b = data.getExtras();
                if(b != null){
                    Log.i("onActvityResult", "not null");
                    returnedFireInfoList = (ArrayList<fireInfo>) data.getSerializableExtra("firesListResult"); 
                    Log.i("onActvityResult", "results Size: "+returnedFireInfoList.size());
                    if(returnedFireInfoList.size()>0){
                        Log.i("onActvityResult", "locationName: "+returnedFireInfoList.get(0).getLocationName());
                        //compare returnedFireInfoList and rePopulatedfireInfoList, if different; 
                        //add difference to rePopulatedfireInfoList and write back to file.
                        updateFireInfos(returnedFireInfoList, rePopulatedfireInfoList);
        if(returnedFireInfoList.size()!=rePopulatedfireInfoList.size()){
mMyFragmentPagerAdapter1 = new fragmentAdapter(getSupportFragmentManager(),orientation
                    ,returnedFireInfoList);
            mPager = (ViewPager)findViewById(R.id.fireInfoFragment_container); 
            Log.i("updateFireInfos", "fragmentsCount is"+mPager.getCurrentItem());
            fireInfoFragment fragment = 
                      (fireInfoFragment) getSupportFragmentManager().findFragmentById(R.id.fireInfoFragment_container);
//This is where the problem is, I don't want to remember what was already on the viewPager //called mPager before.
           //   mPager.removeAllViews();
            //mPager.setAdapter(null);
            mMyFragmentPagerAdapter1.notifyDataSetChanged();            
            mPager.setAdapter(mMyFragmentPagerAdapter1);               mMyFragmentPagerAdapter1.notifyDataSetChanged();                     
                    }                   
                }
            }

这是fragmentStateAdapter代码：

public class fragmentAdapter extends FragmentStatePagerAdapter {

private FragmentManager fragmentManager;
 private FragmentTransaction mCurTransaction = null;
 private ArrayList<Fragment.SavedState> mSavedState = new ArrayList<Fragment.SavedState>();
 private ArrayList<Fragment> mFragments = new ArrayList<Fragment>();
 private Fragment mCurrentPrimaryItem = null;



public void restoreState(Parcelable state, ClassLoader loader) {
    //Need to only delete info from marked fragments (theoned that are stored on orientationchange
    //Currently redoing the entire call; resulting in delay due to server call
    //if(isLastOrientationPortrait != isPortrait){
    if(state != null){
        Bundle bundle1 = (Bundle) state;
        bundle1.setClassLoader(loader);
        Iterable<String> keys = bundle1.keySet();
        Log.i("restoreState", "containsKey FragmentStatePagerAdapter: "+keys);
        //android.support.v4.app.FragmentManager fragmentManager= fragmentAdapter.this.fragmentManager;
        android.support.v4.app.FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction(); 
        //if (fragmentTransaction == null) {
        //  Log.i("restoreState", "fragmentTransactionTest");

            fragmentTransaction = fragmentManager.beginTransaction();
       // }
        for (String key : keys) {
            if (key.startsWith("f")) {
                Fragment f = fragmentManager.getFragment(bundle1,
                        key);
                fragmentTransaction.remove(f);
                fragmentTransaction.commit();
            }
            }
        }
    //}       
    }


@Override
public int getItemPosition(Object object) {
    // TODO Auto-generated method stub
    //return super.getItemPosition(object);
    return fragmentAdapter.POSITION_NONE;
}


public fragmentAdapter(android.support.v4.app.FragmentManager fragmentManager,String orientation,
         ArrayList<fireInfo> fireInfoList) {
     super(fragmentManager);
     this.orientation = orientation;
     this.fireInfoList = fireInfoList;
     this.numItems = fireInfoList.size();
     this.fragmentManager=fragmentManager;
 }
 ArrayList<fireInfo> fireInfoList;
 String orientation;
 int numItems;


@Override
 public int getCount() {
     Log.i("numItems", "is: "+fireInfoList.size());
     return numItems;
 }

@Override
public Fragment getItem(int arg0) {
    Log.i("fragmentAdapterIndex", "is: "+arg0);
    return fireInfoFragment.newInstance(orientation, fireInfoList.get(arg0));
}

}

问题： 但在我触发startActivityFor结果之前，新的ArrayListOfObjects与旧的一起添加。

如何强制viewPager忘记旧内容？基本上使用我的fragmentStateAdapter？

用这个newArrayListofObjects重置viewPager适配器

Answer 1

我想问题在于旧片段仍然存在于您用于适配器的FragmentManager中。如果是这种情况，您只需从片段管理器中删除所有旧片段。

所以基本上只需在适配器的构造函数中执行以下代码：

public fragmentAdapter(FragmentManager fragmentManager, String orientation, ArrayList<fireInfo> list) {
    super(fragmentManager);
    if (fragmentManager.getFragments() != null) {
        fragmentManager.getFragments().clear();
    }
    //... your other code here
}

这行代码是不必要的：

mMyFragmentPagerAdapter1.notifyDataSetChanged();

编辑：使用FragmentTransaction删除片段可能更为正确：

    List<Fragment> fragments = fragmentManager.getFragments();
    if (fragments != null) {
        FragmentTransaction ft = fragmentManager.beginTransaction();
        for (Fragment f : fragments) {
            //You can perform additional check to remove some (not all) fragments:
            if (f instanceof AddedByCurrentPagerAdapterFragment) { 
                ft.remove(f);
            }
        }
        ft.commitAllowingStateLoss();
    }

FragmentTransaction执行（异步）需要一些时间。

Answer 2

我需要做的就是重新分配FragmentStatePagerAdapter。

这已经在onActivityResult中可以看到，但屏蔽了正确行为的是我的viewPager页面指示器，它正在递增页面，例如如果我在viewPager上有2个页面并调用子actvity，它将在arrayListOfObjects上添加一个对象; viewPager页面指示器将显示我现在有2加3页（5）。

我不得不重置onActivityResult中的viewPage指示符，让它由浮动活动刚刚返回的这个新的arrayListOfObjects确定。

从FragmentStatePagerAdapter填充的ViewPager中删除所有片段

2 个答案: