getItem()在FragmentPagerAdapter中多次调用

Question

我正在使用带有fragment的viewpager开发应用程序.在我的应用程序中,我有一个项目,我在List.After,当我点击我已经调用SherlockFragmentActivity调用ViewPager与适配器.现在问题是在FragmentPagerAdapter getItem给一个单一的位置时间.当我翻转后记然后也给错了位置.这是我的代码

ViewPager代码: -

private void initialisePaging() {
            //Adapter Context;
    this.mPagerAdapter = new MyPagerAdapter(
            super.getSupportFragmentManager(), getApplicationContext(),
            title, link, description);


    ViewPager pager = (ViewPager) super.findViewById(R.id.viewpager);
    pager.setAdapter(this.mPagerAdapter);
           //Take position from ListView & set postion .
    pager.setCurrentItem(post_position);
}

我的适配器类负责设置片段: -

问题: - 问题是getItem调用3次&假设我点击4项它给我3,4,5号码.

public MyPagerAdapter(FragmentManager fm, Context cont,
            ArrayList<String> title, ArrayList<String> link,
            ArrayList<String> description) {

             super(fm);
    this.context = cont;
    this.key_desc = description;
    this.key_link = link;
    this.key_title = title;
    viewPagerApplication = (RssItem) cont;

}

@Override
public Fragment getItem(int position) {
        return Fragment0.newInstance(position, this.context, key_title,
            key_link, key_desc);
}

@Override
public int getCount() {
     return key_title.size();
}
My Fragment Class:-

Problem:-Here if i show postion in textview its correct position but if i want take position in logcat for further parsing its giving me again 4,3,5 number which is also diffrent from getItem();

public static Fragment0 newInstance(int num,Context cont, ArrayList<String> key_title, ArrayList<String> key_link, ArrayList<String> key_desc) {
    context=cont;



    Fragment0 f = new Fragment0();
    Bundle args = new Bundle();
    args.putInt("num", num);
    f.setArguments(args);

    return f;
}


 public void onCreate(Bundle savedInstanceState) {

   super.onCreate(savedInstanceState);






 };

   public int getShownIndex() {
       return getArguments().getInt("num", 0);
   }
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
         View v = inflater.inflate(R.layout.newsdetailfragment_screen, container, false);
          tv = v.findViewById(R.id.headingtextview_id);
         ((TextView)tv).setText(String.valueOf(getShownIndex()));
          ((TextView)tv).setTextColor(Color.BLACK);
         ((TextView)tv).setTextSize(20);
           return v;
    }

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

现在请让我知道我哪里错了,我怎样才能获得一个确切的位置以便进一步处理.

Answer 1

在getItem()内部,position参数是需要渲染的位置.它不是用户可以看到的当前焦点项目的位置.当前显示的视图左侧和右侧的页面需要预先渲染在内存中,以便这些屏幕的动画流畅.要使项目处于当前位置,请使用:

pager.getCurrentItem();

如果您需要页面的实际位置,可以在onPageChangeListener上实现

pager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
        @Override
        public void onPageSelected(int position) {
}

onPageSelected中的位置将给出页面的准确当前位置.