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我有問題FragmentPagerAdapter,我已經通過FragmentPagerAdapter設置在viewpager片段, 我有動態地顯示viewpager,我有列表視圖數據,這是我需要顯示在viewpager, 當我點擊列表視圖時,我不得不加載視圖中的確切位置 所以我只是設置項目的總大小顯示在FragmentPagerAdapter,但問題是,當我通過mPager.setCurrentItem(listposition)選擇viewpager位置顯示視圖的正確位置, 但數據加載錯誤的地方,它加載在viewpager位置下一個fragement,在FragmentPagerAdapter中的一些跟蹤後,我表明我nstantiateItem方法提前初始化一個片段,就像我設置viewpager 2的當前項目(從列表視圖)然後instantiateItem方法initalize 0到3片段,我認爲數據加載到第三個片段的原因,我也嘗試了很多與FragmentStatePagerAdapter但也沒有任何成功,請幫助我,在此先感謝。的Android Viewpager.setCurrentitem()和FragmentPagerAdapter instantiateItem()片段initailize失配

MainActivity類別(Fragmnetactivity):

public class NewsDetail extends FragmentActivity implements OnClickListener { 
    public static ViewPager mPager; 
    private static int NUM_PAGES; 
    private PagerAdapter mPagerAdapter; 
    public static ArrayList<Integer> exist_detail = new ArrayList<Integer>(); 
    public static ArrayList<PageFragment> detailfragment = new ArrayList<PageFragment>(); 


    mPager = (ViewPager) findViewById(R.id.pager); 
    mPagerAdapter = new ScreenSlidePagerAdapter(getSupportFragmentManager()); 
    mPager.setAdapter(mPagerAdapter); 

    NUM_PAGES = topList.size(); 
    PageFragment fragment = new PageFragment(); 
    Bundle args = new Bundle(); 
    args.putInt("page", i); 
    fragment.setArguments(args); 
    detailfragment.add(fragment); 

    mPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() { 

     @Override 
     public void onPageSelected(int arg0) { 
       if (PageFragment.getInstance() != null) { 
        Log.d("LOG","PageFragment || "+ PageFragment.getInstance()); 
        PageFragment.getInstance().startLoadingNews(
          MusicList.topMusicList.get(arg0)._id); 
       } 
      return; 
     } 

     @Override 
     public void onPageScrolled(int arg0, float arg1, int arg2) {} 

     @Override 
     public void onPageScrollStateChanged(int arg0) {} 
    }); 
    mPagerAdapter.notifyDataSetChanged(); 

    mPager.setCurrentItem(listposition);// setcurrent item from here , it is selected from list. "listposition" indicate list position click 



    private class ScreenSlidePagerAdapter extends FragmentPagerAdapter { 

      private FragmentManager mFragmentManager; 
      private FragmentTransaction mCurTransaction = null; 
      private Fragment mCurrentPrimaryItem = null; 
      private static final boolean DEBUG = false; 

      public ScreenSlidePagerAdapter(FragmentManager fragmentManager) { 
       super(fragmentManager); 
       this.mFragmentManager = fragmentManager; 
      } 

      @Override 
      public Fragment getItem(int position) { 

       return detailfragment.get(position); 
      } 

      @Override 
      public long getItemId(int position) { 
       // TODO Auto-generated method stub 
       return super.getItemId(position); 
      } 

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

       Log.v("LOG", "On InstantiateItem " + position);// it indicate that this method initialize one fragment in advance. 

       return super.instantiateItem(container, position); 
      } 

      public String makeFragmentName(int viewId, long index) { 
       return "android:switcher:" + viewId + ":" + index; 
      } 

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

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

      @Override 
      public int getCount() { 
       return NUM_PAGES; 
      } 
     } 
     } 

PageFragment

 public class PageFragment extends Fragment implements OnClickListener { 

      @Override 
      public void onCreate(Bundle savedInstanceState) { 
       super.onCreate(savedInstanceState); 
       mPageNumber = getArguments().getInt(ARG_PAGE); 
       mDetailPageFragment = this; 
      } 

      @Override 
      public View onCreateView(LayoutInflater inflater, ViewGroup container, 
        Bundle savedInstanceState) { 
       // Inflate the layout containing a title and body text. 
       rootView = (ViewGroup) inflater.inflate(R.layout.newsdetail, container, 
         false); 
       //init(); 
       return rootView; 
      } 
      public void startLoadingNews(String _id) { 

       if (NetworkUtil.cheackNetwork(mActivity)) { 
        executeTask(_id); 
       } else { 
        showRetryCancelDialog(); 
       } 
      } 
      } 

回答

0

我可以看到在兩個代碼問題您已經發布:

  1. 只有實例你的片段在FragmentPagerAdapter.getItem。不要實例化它們並將它們保存到某個列表或數組中,讓FragmentPagerAdapter爲您做到這一點。在FragmentPagerAdapter.instantiateItem它檢查Fragment是否已經創建,如果是,則返回它,否則它會調用getItem來創建片段。
  2. 不要對您的片段使用Singleton方案,請使用構造函數或.newInstance()靜態幫助器創建新片段。
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