android - 无法从 ViewPager 中删除 fragment ，为什么？

Question

我一定是遗漏了什么，但我无法从我的 ViewPager 中删除 fragment 。我将页面标题存储在 ArrayList 中:

部分 ViewPagerActivity.java(这是一个 FragmentActivity，主要 Activity ):

public static ArrayList<String> mEntries = new ArrayList<String>();

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate( savedInstanceState );
    setContentView( R.layout.main );
    context=this;

    mEntries.add("   111");
    mEntries.add("   222");
    mEntries.add("   333");
    mEntries.add("   444");
    mEntries.add("   555");
    mEntries.add("   666");

    List<String> fragments = new Vector<String>();

    fragments.add(111.class.getName());
    fragments.add(222.class.getName());
    fragments.add(333.class.getName());
    fragments.add(444.class.getName());
    fragments.add(555.class.getName());
    fragments.add(666.class.getName());

    this.mPagerAdapter = new PagerAdapter1(super.getSupportFragmentManager(), fragments);
    pager = (ViewPager)super.findViewById(R.id.viewpager);
    pager.setAdapter(this.mPagerAdapter);
    // ...

我有一个 fragment (111)，我想通过单击 111 中的按钮删除 555 fragment 。 (因为它以 0 开头，所以 555 是第 4 个 fragment )。

fragment111.java 的一部分(它是一个Fragment):

     button.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
           ViewPagerActivity.mEntries.remove(5);
     ViewPagerActivity.mPagerAdapter.removeX(5);
    ViewPagerActivity.mPagerAdapter.removeX2(5);
    ViewPagerActivity.pager.setAdapter( ViewPagerActivity.mPagerAdapter);
    ViewPagerActivity.pager.getAdapter().notifyDataSetChanged();    
   }
        });

我有一些人通过覆盖 getItemPosition() 方法而错过的 POSITION_NONE 东西。

我的适配器类:

  public class PagerAdapter1 extends FragmentStatePagerAdapter {

    private List<String> fragments;
       private static final String TAG = "FragmentPagerAdapter";
        private static final boolean DEBUG = true;
        private Fragment mCurrentPrimaryItem = null;
        private final FragmentManager mFragmentManager;
        private FragmentTransaction mCurTransaction = null;

    /**
     * @param fm
     * @param fragments2
     */
    public PagerAdapter1(FragmentManager fm, List<String> fragments2) {
        super(fm);
        mFragmentManager=fm;
        this.fragments = fragments2;
    }
    /* (non-Javadoc)
     * @see android.support.v4.app.FragmentPagerAdapter#getItem(int)
     */
    @Override
    public Fragment getItem(int position) {
        //return this.fragments.get(position);
        return Fragment.instantiate(ViewPagerActivity.context, fragments.get(position));

    }

    /* (non-Javadoc)
     * @see android.support.v4.view.PagerAdapter#getCount()
     */
    @Override
    public int getCount() {
        return this.fragments.size();
    }



      /**
     * Return the Fragment associated with a specified position.
     */


    @Override
    public void startUpdate(ViewGroup container) {
    }

    @Override
    public Object instantiateItem(ViewGroup container, int position) {

        if (mCurTransaction == null) {
            mCurTransaction = mFragmentManager.beginTransaction();
        }

        final long itemId = getItemId(position);

        // Do we already have this fragment?
        String name = makeFragmentName(container.getId(), itemId);

        Fragment fragment = mFragmentManager.findFragmentByTag(name);
        if (fragment != null) {
            if (DEBUG) Log.v(TAG, "Attaching item #" + itemId + ": f=" + fragment);
                mCurTransaction.attach(fragment);

        } else {

            fragment = getItem(position);

            if (DEBUG) Log.v(TAG, "Adding item #" + itemId + ": f=" + fragment);
            mCurTransaction.add(container.getId(), fragment,
                    makeFragmentName(container.getId(), itemId));

        }

        if (fragment != mCurrentPrimaryItem) {
            fragment.setMenuVisibility(false);
            fragment.setUserVisibleHint(false);
        }


        return fragment;
    }


    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        if (mCurTransaction == null) {
            mCurTransaction = mFragmentManager.beginTransaction();
        }
        if (DEBUG) Log.v(TAG, "Detaching item #" + getItemId(position) + ": f=" + object
                + " v=" + ((Fragment)object).getView());
        mCurTransaction.detach((Fragment)object);
    }

    @Override
    public void setPrimaryItem(ViewGroup container, int position, Object object) {
        Fragment fragment = (Fragment)object;
        if (fragment != mCurrentPrimaryItem) {
            if (mCurrentPrimaryItem != null) {
                mCurrentPrimaryItem.setMenuVisibility(false);
                mCurrentPrimaryItem.setUserVisibleHint(false);
            }
            if (fragment != null) {
                fragment.setMenuVisibility(true);
                fragment.setUserVisibleHint(true);
            }
            mCurrentPrimaryItem = fragment;
        }


    }

    @Override
    public void finishUpdate(ViewGroup container) {
        if (mCurTransaction != null) {
            mCurTransaction.commitAllowingStateLoss();
            mCurTransaction = null;
            mFragmentManager.executePendingTransactions();
        }

    }

    @Override
    public boolean isViewFromObject(View view, Object object) {
        return ((Fragment)object).getView() == view;
    }

    @Override
    public Parcelable saveState() {
        return null;
    }

    @Override
    public void restoreState(Parcelable state, ClassLoader loader) {
    }

    /**
     * Return a unique identifier for the item at the given position.
     *
     * <p>The default implementation returns the given position.
     * Subclasses should override this method if the positions of items can change.</p>
     *
     * @param position Position within this adapter
     * @return Unique identifier for the item at position
     */
    public long getItemId(int position) {
        return position;
    }

    private static String makeFragmentName(int viewId, long id) {
        return "android:switcher:" + viewId + ":" + id;
    }

    @Override
    public int getItemPosition(Object object) {
        return POSITION_NONE;
    }


   public void removeX(int position){
        fragments.remove(5);
}        


public void removeX2(int position){

    Fragment ff =  getItem(position);
    mFragmentManager.beginTransaction().remove(ff).commit();
    notifyDataSetChanged();
}

}

我正在使用 FragmentStatePagerAdapter 并且 notifyDataSetChanged() 运行良好(我更新了 CheckBox 的状态并且我看到它运行良好)。如何从 ViewPager 中删除此 fragment ？

提前致谢!

Answer 1

我遇到了同样的问题，我找到的唯一解决方案是在删除 fragment 后再次设置适配器，如下所示:

@Override
    public void onClick(View v) {
    ViewPagerActivity.mEntries.remove(4);
    pager.setAdapter(mPagerAdapter);
    }

更新:您不需要重新设置适配器。这是我的 PagerAdapter 的一些方法，您可能需要做一些修改才能将其用作 FragmentPagerAdapter

删除 View :

public static void deleteChildren(int pStart) {

    List<ViewInfo> viewToRemove = new ArrayList<ViewInfo>();

    for (int iView = pStart+1; iView < _views.size(); iView++) {
        viewToRemove.add(_views.get(iView));
    }

    if (viewToRemove.size() != 0) {
        _views.removeAll(viewToRemove);
    }
}

@Override
public void destroyItem(View pView, int pIndex, Object pObject) {
        ((ViewPager) pView).removeView((View)pObject);
}

覆盖 getItemPosition(Object pObject) :

    @Override
public int getItemPosition(Object pObject) {
    int pos = 0;
    for (ViewInfo iView : _views) {
        if (iView.mView == (View)pObject) {

            break;
        }
        pos++;
    }
    return pos;
}

刷新所有 View :

public static void refreshAdapterViewPager() {
    _pagerAdapter.notifyDataSetChanged();

}