Question

我有一个片段活动有4个页面并从4个链接加载来自互联网当程序启动自定义列表显示列表但当我更改页面时，视图显示白页

我的片段：

public class VpiAbsTestActivitynouser extends SherlockFragmentActivity {


private static final String[] CONTENT = new String[] {" page1","page2","page3","page4"};

TestFragmentAdapter mAdapter;
 ViewPager mPager;
    PageIndicator mIndicator;
    TextView mSearchView;


    public String[] xmlURLArray = new String[]{"link1.xml","link2.xml","link3.xml","link4.xml"};


protected void onCreate(Bundle savedInstanceState) {
    setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
    super.onCreate(savedInstanceState);
    setContentView(R.layout.simple_tabs);

    Intent i = new Intent(this, transparentone.class);
    startActivity(i);

    mAdapter = new TestFragmentAdapter(getSupportFragmentManager());
    mPager = (ViewPager)findViewById(R.id.pager);
    mPager.setAdapter(mAdapter);
    mIndicator = (TabPageIndicator)findViewById(R.id.indicator);
    mIndicator.setViewPager(mPager);
    mIndicator.setCurrentItem(1);


}


class TestFragmentAdapter extends FragmentPagerAdapter {        
    private int mCount = CONTENT.length;

    public TestFragmentAdapter(FragmentManager fm) {
        super(fm);

    }

    @Override
    public Fragment getItem(int position) {
            Bundle args = new Bundle();
            args.putString("url", xmlURLArray[position]);

        return  customlist.newInstance(args);

    }



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


    public CharSequence getPageTitle(int position) {
        return VpiAbsTestActivitynouser.CONTENT[position % VpiAbsTestActivitynouser.CONTENT.length].toUpperCase();
    }

     @Override
        public void destroyItem(View collection, int position, Object view) {
             ((ViewPager) collection).removeView((View) view);

        }



 }

}

我的自定义列表代码是：

public class customlist extends SherlockFragment  {
int fragment_position_in_viewpager = 0;

// All static variables

 public static customlist newInstance(Bundle args) {
        customlist fragment = new customlist();
        fragment.setArguments(args);
        return fragment;
        }

ListView list;
LazyAdapterbeth adapter1;



public void onActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);


        }


public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    if (getArguments() != null) { 
        URL = getArguments().getString("url"); 
        } 
        new getFeed().execute(); 
} 

public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
     ViewGroup root = (ViewGroup) inflater.inflate(
                R.layout.dovomi, container, false);



        return root;
    }

public void onViewCreated(View view, Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);

    if (getArguments() != null) {
        fragment_position_in_viewpager = getArguments().getInt("position");
        //Update the Fragment on ViewPager Position.
    }


}


private class getFeed extends AsyncTask<Void, Void, Document> {

       @Override
       protected void onPreExecute() { 
       }

    protected Document doInBackground(Void... params) {
    }

    protected void onPostExecute(Document doc) {
    }



    list=(ListView)getView().findViewById(R.id.list);
    adapter1=new LazyAdapterbeth(getActivity(), songsList);
    adapter1.notifyDataSetChanged();
    list.setAdapter(adapter1);

将视图从第1页更改为第2页时，如何刷新视图？

Answer 1

由于您的代码很长，我没有深入分析，但我想到了以下解决方案：

1）在重新创建片段/重新创建视图层次结构时，会定期调用每个片段方法的onCreateView

因此，它可以是一个令人耳目一新的地方。但是，onCreateView的调用时间略早于分页显示之前（通常在显示页面nr 2的位置，执行第3页的onCreateView）。最好的想法是在onCreateView中放置一个显示Toast的短代码，然后你会知道它是否适合你。

2）你的主要活动（扩展FragmentActivity）可以获得3个在片段之间滑动时执行的方法。它将以下列方式看起来或多或少：

public MyActivity extends FragmentActivity implements OnPageChangeListener {

@Override
    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
         mainActivityPageAdapter = new MainActivityPageAdapter (this, getSupportFragmentManager());
        mainActivityViewPager = (ViewPager) findViewById(R.id.main_activity_view_pager);
        mainActivityViewPager.setAdapter(mainActivityPageAdapter);

        //set listener (for navigator)
        mainActivityViewPager.setOnPageChangeListener(this);

}

//and now you have 3 methods
    @Override
    public void onPageScrollStateChanged(int state) {
    }

    @Override
    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

    }

    @Override
    public void onPageSelected(int position) {
}

您可以阅读更多http://developer.android.com/reference/android/support/v4/view/ViewPager.OnPageChangeListener.html

更改页面时如何刷新视图？

1 个答案: