我的Activity中有一个带有4个标签的TabLayout，我为每个标签制作了一个片段。
以下是我的活动代码：
public class MyActivity extends AppCompatActivity {
private static final String TAG = "RecyclerView";
private Toolbar toolbar;
private static ViewPager viewPager;
private static TabLayout tabLayout;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
/* Allow activity to show indeterminate progressbar */
requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS);
setContentView(R.layout.student_regulations_list);
toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
viewPager = (ViewPager) findViewById(R.id.viewPager);
setupViewPager(viewPager);
tabLayout = (TabLayout) findViewById(R.id.tabLayout);
tabLayout.setupWithViewPager(viewPager);
tabLayout.setOnTabSelectedListener(onTabSelectedListener(viewPager));
}
private void setupViewPager(ViewPager viewPager) {
ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
adapter.addFragment(new Fragment1(), getString(R.string.titleA));
adapter.addFragment(new Fragment2(), getString(R.string.titleB));
adapter.addFragment(new Fragment3(), getString(R.string.titleC));
adapter.addFragment(new Fragment4(), getString(R.string.titleD));
viewPager.setAdapter(adapter);
viewPager.setOffscreenPageLimit(3);
viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
}
private TabLayout.OnTabSelectedListener onTabSelectedListener(final ViewPager viewPager) {
return new TabLayout.OnTabSelectedListener() {
@Override
public void onTabSelected(TabLayout.Tab tab) {
viewPager.setCurrentItem(tab.getPosition());//setting current selected item over viewpager
}
@Override
public void onTabUnselected(TabLayout.Tab tab) {
}
@Override
public void onTabReselected(TabLayout.Tab tab) {
}
};
}
//View Pager fragments setting adapter class
class ViewPagerAdapter extends FragmentPagerAdapter {
private final List<Fragment> mFragmentList = new ArrayList<>();//fragment arraylist
private final List<String> mFragmentTitleList = new ArrayList<>();//title arraylist
public ViewPagerAdapter(FragmentManager manager) {
super(manager);
}
@Override
public Fragment getItem(int position) {
return mFragmentList.get(position);
}
@Override
public int getCount() {
return mFragmentList.size();
}
//adding fragments and title method
public void addFragment(Fragment fragment, String title) {
mFragmentList.add(fragment);
mFragmentTitleList.add(title);
}
@Override
public CharSequence getPageTitle(int position) {
return mFragmentTitleList.get(position);
}
}
我在每个片段中都有一个RecyclerView，我使用AsyncTask从Web服务获取数据，以显示在RecyclerView中。 RecyclerView中的每个项目都有一个ID，我想当我在选项卡之间切换并点击RecyclerView中的项目时，Toast会显示它的ID。
下面是片段代码：
public class Fragment1 extends Fragment implements ClickListener {
private static final String TAG = "RecyclerView";
private List<FeedItem> feedItemList;
private RecyclerView mRecyclerView;
private FeedsRecyclerAdapter mAdapter;
final String url = "a valid url";
private View rootView;
private ProgressBar progressBar;
public StuRegGeneralListFragment() {
}
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container,
@Nullable Bundle savedInstanceState) {
rootView = inflater.inflate(R.layout.fragment_student_regulations_list, container, false);
return rootView;
}
@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
progressBar = (ProgressBar) rootView.findViewById(R.id.progress_bar);
/* Initialize recyclerview */
mRecyclerView = (RecyclerView) rootView.findViewById(R.id.recycler_view);
mRecyclerView.setHasFixedSize(true);
mRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
/*Downloading data from below url*/
new AsyncHttpTask().execute(url);
}
@Override
public void itemClicked(View view, int position) {
FeedItem item = feedItemList.get(position);
Intent intent = new Intent(getActivity(), JsonRequestFeedActivity.class);
intent.putExtra("url", Const.URL_JSON_OBJECT_REGS + item.getID());
intent.putExtra("pid", item.getID());
//startActivity(intent);
Toast.makeText(getActivity(), "Item ID: " + item.getID(), Toast.LENGTH_SHORT).show();
}
public class AsyncHttpTask extends AsyncTask<String, Void, Integer> {
@Override
protected void onPreExecute() {
progressBar.setVisibility(View.VISIBLE);
feedItemList = new ArrayList<FeedItem>();
}
@Override
protected Integer doInBackground(String... params) {
InputStream inputStream = null;
Integer result = 0;
HttpURLConnection urlConnection = null;
try {
/* forming th java.net.URL object */
URL url = new URL(params[0]);
urlConnection = (HttpURLConnection) url.openConnection();
/* for Get request */
urlConnection.setRequestMethod("GET");
int statusCode = urlConnection.getResponseCode();
/* 200 represents HTTP OK */
if (statusCode == 200) {
BufferedReader r = new BufferedReader(new InputStreamReader(urlConnection.getInputStream()));
StringBuilder response = new StringBuilder();
String line;
while ((line = r.readLine()) != null) {
response.append(line);
}
parseResult(response.toString());
result = 1; // Successful
} else {
result = 0; //"Failed to fetch data!";
}
} catch (Exception e) {
Log.d(TAG, e.getLocalizedMessage());
}
return result; //"Failed to fetch data!";
}
@Override
protected void onPostExecute(Integer result) {
progressBar.setVisibility(View.GONE);
/* Download complete. Lets update UI */
if (result == 1) {
updateRecyclerView();
} else {
Log.e(TAG, "Failed to fetch data!");
}
}
}
private void parseResult(String result) {
try {
JSONObject response = new JSONObject(result);
JSONArray posts = response.optJSONArray("posts");
/*Initialize array if null*/
if (null == feedItemList) {
feedItemList = new ArrayList<FeedItem>();
}
for (int i = 0; i < posts.length(); i++) {
JSONObject post = posts.optJSONObject(i);
FeedItem item = new FeedItem();
item.setID(post.optString("id"));
item.setDate(post.optString("date"));
item.setTitle(post.optString("title"));
item.setThumbnail(post.optString("thumbnail"));
feedItemList.add(item);
}
} catch (JSONException e) {
e.printStackTrace();
}
}
public void updateRecyclerView() {
mAdapter = new FeedsRecyclerAdapter(getActivity(), feedItemList);
mRecyclerView.setAdapter(mAdapter);
mAdapter.setClickListener(this);
}
}
假设每个片段在RecyclerView中有5个项目（在片段1中从ID 1到5，从片段2中的ID 6到10，......）我希望当我进入我的Activity并单击fragment1中的项目时（例如第一项），ID = 1显示在Toast中，但显示ID = 16！
实际上是因为viewPager.setOffscreenPageLimit（3）;在我的Activity中，创建了fragment1和fagment2以及fragment3和fragment4，最后，mAdapter包含项目ID 16-20，尽管我在fragment1中。 我希望在viewPager.setOffscreenPageLimit（int）创建指定的片段之后;每个片段都有它自己的适配器，但它没有发生。
感谢任何帮助。
答案 0 :(得分：0)
我发现了我的错误！
我的活动和片段代码是正确的，我的错误在于RecyclerView的ClickListener。它的实施并不适合我的情况。
我在其中使用过静态clickListener，这就是重点！