我知道同样的问题被问了很多次，但我无法解决我的问题。
我创建的Activity ViewPager应该有4 Pages。
我对所有网页使用相同的Fragment。 Fragment有一个GridView，只要我滑到另一个页面，就应该更新activity_discover.xml。
以下是课程＆amp;我用来创建它的XML布局。
活动布局 <android.support.v4.view.ViewPager
android:id="@+id/activity_discover_view_pager"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="10dip" >
<android.support.v4.view.PagerTabStrip
android:id="@+id/activity_discover_pager_tab_strip"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="@color/white"
android:textColor="@color/black"
android:textSize="@dimen/header_text" />
</android.support.v4.view.ViewPager>
</RelativeLayout>
DiscoverActivity.java活动public class DiscoverActivity extends FragmentActivity implements OnClickListener, OnPageChangeListener
{
private final static String TAG = "DiscoverActivity";
private UtilDialog utilDialog;
MPagerAdapter adapterViewPager;
PagerTabStrip pagerTabStrip;
ViewPager viewPager;
public ArrayList<String> listCategory;
LMProgressDialog progressDialog;
private RelativeLayout relativeCountry;
private RelativeLayout relativeCity;
private TextView tvCountry;
private TextView tvCity;
private String selectedCategory;
private int selectedCityID = 0;
private int selectedCategoryID = 0;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_discover);
initParameters();
initView();
}
void initParameters()
{
progressDialog = new LMProgressDialog(this);
utilDialog = new UtilDialog(this);
preferences = PreferenceManager.getDefaultSharedPreferences(this);
editor = preferences.edit();
editor.commit();
selectedCategory = getResources().getString(R.string.adventure);
listCategory = new ArrayList<String>();
listCategory.add(getResources().getString(R.string.adventure));
listCategory.add(getResources().getString(R.string.night_life));
listCategory.add(getResources().getString(R.string.life_styles));
listCategory.add(getResources().getString(R.string.events));
}
void initView()
{
viewPager = (ViewPager) findViewById(R.id.activity_discover_view_pager);
viewPager.setOnPageChangeListener(this);
adapterViewPager = new MPagerAdapter(getSupportFragmentManager());
viewPager.setAdapter(adapterViewPager);
pagerTabStrip = (PagerTabStrip) findViewById(R.id.activity_discover_pager_tab_strip);
pagerTabStrip.setTabIndicatorColor(getResources().getColor(R.color.white));
}
@Override
protected void onDestroy()
{
super.onDestroy();
}
public class MPagerAdapter extends FragmentPagerAdapter
{
private Map<Integer, String> mFragmentTags;
private FragmentManager mFragmentManager;
public MPagerAdapter(FragmentManager fm)
{
super(fm);
mFragmentManager = fm;
mFragmentTags = new HashMap<Integer, String>();
}
@Override
public int getCount()
{
return 4;
}
@Override
public Fragment getItem(int position)
{
Fragment fragment = Fragment.instantiate(DiscoverActivity.this,
FragmentMediaContent.class.getName(), null);
return fragment;
}
@Override
public Object instantiateItem(ViewGroup container, int position)
{
Object obj = super.instantiateItem(container, position);
if (obj instanceof Fragment)
{
// record the fragment tag here.
Fragment f = (Fragment) obj;
String tag = f.getTag();
mFragmentTags.put(position, tag);
}
return obj;
}
public Fragment getFragment(int position)
{
String tag = mFragmentTags.get(position);
if (tag == null)
return null;
return mFragmentManager.findFragmentByTag(tag);
}
@Override
public CharSequence getPageTitle(int position)
{
return listCategory.get(position).toString().toUpperCase();
}
}
@Override
public void onPageScrollStateChanged(int arg0)
{
}
@Override
public void onPageScrolled(int arg0, float arg1, int arg2)
{
}
@Override
public void onPageSelected(int position)
{
selectedCategoryID = position;
selectedCategory = listCategory.get(position);
try
{
JSONObject jsonObject = new JSONObject();
jsonObject.put(Constants.CITY_ID, selectedCityID);
jsonObject.put(Constants.CATEGORY, selectedCategory);
makeJsonObjectRequest(Request.Method.POST, jsonObject, API.URL_LOAD_MEDIA);
} catch (JSONException e)
{
e.printStackTrace();
}
}
void prepareMediaList(JSONArray arrayMedia)
{
int noOfMedia = arrayMedia.length();
ArrayList<MediaType> listMedia = new ArrayList<MediaType>();
for (int i = 0; i < noOfMedia; i++)
{
try
{
JSONObject objectMedia = arrayMedia.getJSONObject(i);
int id = objectMedia.getInt(Constants.ID);
String category = objectMedia.getString(Constants.CATEGORY);
String mediaType = objectMedia.getString(Constants.MEDIA_TYPE);
int cityID = objectMedia.getInt(Constants.CITIES_ID);
String path = objectMedia.getString(Constants.PATH);
String thumbnailPath = objectMedia.getString(Constants.THUMBNAIL_PATH);
String description = objectMedia.getString(Constants.DESCRIPTION);
int userID = objectMedia.getInt(Constants.USERS_ID);
listMedia.add(new MediaType(id, mediaType, path, category, userID, cityID, 0, description, thumbnailPath));
} catch (JSONException e)
{
e.printStackTrace();
}
}
FragmentMediaContent fragment = (FragmentMediaContent) adapterViewPager.getFragment(selectedCategoryID);
Log.i(TAG, "fragment: " + fragment);
fragment.updateData(listMedia, selectedCategory);
}
}
Fragment FragmentMediaContent.java课程public class FragmentMediaContent extends Fragment
{
private final static String TAG = "FragmentMediaContent";
public static final String FRAGMENT_POSITION = null;
private GridView gridView;
private UtilDialog utilDialog;
private SharedPreferences preferences;
private Editor editor;
private ArrayList<MediaType> listMedia;
MediaAdapter mediaAdapter;
private int cityID;
private String category;
LMProgressDialog progressDialog;
TextView tvTest;
public static FragmentMediaContent newInstance(int num)
{
FragmentMediaContent f = new FragmentMediaContent();
return f;
}
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState)
{
return inflater.inflate(R.layout.fragment_media_content, container, false);
}
@Override
public void onViewCreated(View view, Bundle savedInstanceState)
{
super.onViewCreated(view, savedInstanceState);
initParameters();
initViews();
}
void initParameters()
{
getSize();
listMedia = new ArrayList<MediaType>();
utilDialog = new UtilDialog(getActivity());
progressDialog = new LMProgressDialog(getActivity());
preferences = PreferenceManager.getDefaultSharedPreferences(getActivity());
editor = preferences.edit();
mediaAdapter = new MediaAdapter(getActivity(), listMedia);
}
void initViews()
{
tvTest = (TextView) getActivity().findViewById(R.id.fragment_media_content_tv_test);
tvTest.setText(category+" no of media");
tvTest.setVisibility(View.GONE);
gridView = (GridView) getActivity().findViewById(R.id.fragment_media_content_grid_view);
gridView.setAdapter(mediaAdapter);
}
/**
* MediaAdapter : ArrayAdapter class which prepares view for list of
* MediaType.
*
*/
class MediaAdapter extends ArrayAdapter<MediaType>
{
MediaAdapter(Context context, ArrayList<MediaType> list)
{
super(context, R.layout.cell_media_view, R.id.cell_media_view_tv_test, list);
}
public View getView(int position, View convertView, ViewGroup parent)
{
View row = super.getView(position, convertView, parent);
MediaViewHolder holder = (MediaViewHolder) row.getTag();
if (holder == null)
{
holder = new MediaViewHolder(row);
row.setTag(holder);
}
final MediaType mediaType = getMedia(position, this);
String thumbnailPath = mediaType.getThumbnailPath();
String path = mediaType.getPath();
String type = mediaType.getMediaType();
// imageLoader.get(type.equals(Constants.TYPE_IMAGE) ? path :
// thumbnailPath, ImageLoader.getImageListener(holder.ivMedia,
// R.drawable.logo, R.drawable.ic_launcher));
holder.ivType.setVisibility(type.equals(Constants.TYPE_IMAGE) ? View.GONE : View.VISIBLE);
holder.ivMedia.setLayoutParams(new FrameLayout.LayoutParams(THUMBNAIL_SIZE, THUMBNAIL_SIZE));
Picasso.with(getActivity()).load(type.equals(Constants.TYPE_IMAGE) ? path : thumbnailPath).noFade().centerCrop().resize(THUMBNAIL_SIZE, THUMBNAIL_SIZE).placeholder(R.drawable.loading)
.error(R.drawable.no_image).into(holder.ivMedia);
return row;
}
}
public void updateData(ArrayList<MediaType> listMedia, String category)
{
Log.i(TAG, "Updating data for: " + category);
Log.i(TAG, "No of media items: " + listMedia.size());
// this.listMedia.clear();
// this.listMedia.addAll(listMedia);
// mediaAdapter.notifyDataSetChanged();
mediaAdapter = new MediaAdapter(getActivity(), listMedia);
gridView.setAdapter(mediaAdapter);
tvTest.setText(category + ", No of Media : " + listMedia.size());
}
int THUMBNAIL_SIZE = 200;
/**
* @param position
* @return MediaType object from specified position
*/
private MediaType getMedia(int position, MediaAdapter mediaAdapter)
{
return (MediaType) mediaAdapter.getItem(position);
}
}
：
Fragment fragment_media_content.xml <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@color/blue"
android:gravity="center"
android:orientation="vertical" >
<TextView
android:id="@+id/fragment_media_content_tv_test"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textColor="@color/white" />
<GridView
android:id="@+id/fragment_media_content_grid_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:horizontalSpacing="5dip"
android:numColumns="3"
android:verticalSpacing="5dip" />
</LinearLayout>
：
Fragment在页面滑动（或者它可能是任何其他事件）我点击了一个API，它给了我一些我必须在相应的prepareMediaList中更新的数据。
每当我从服务器获取数据时，我都会调用调用updateData Fragment方法的Fragment方法。我可以在日志中看到列表中有数据但该数据未显示在GridView的{{1}}中（甚至不在TextView中）。
我真的没有弄到这个错误。
现在它变得非常令人沮丧，看起来很简单，但仍然找不到任何解决方案。
修改
我刚试过只有一个Fragment＆amp;它运作正常。所以有些东西与倍数有关。
修改2
我无法找到解决方案，因此我不得不切换到替代方式。我从Fragment中移除了ViewPager，而是向其添加了静态视图。在我的情况下，我向GridView添加了四个ViewPager。这很简单＆amp;有点复杂，但最重要的是，它按照我想要的方式工作。
但我仍在寻找答案。
答案 0 :(得分：0)
在详细检查您的代码后，我发现您不需要在updateData方法中重新启动MediaAdapter。
您只需要将updateData更新为
listMedia.clear();
this.listMedia.addAll(listMedia);
mediaAdapter.notifyDatasetChanged();
这将在gridview中重新加载您的数据。我建议的更改将刷新用于渲染gridview的arraylist中的数据，然后通知mediaAdapter重新加载列表。