每次更改选项卡时，选项卡片段都会获取数据

activity_profile.xml

ProfileActivity.java

 package com.stalker.androidapp; import java.util.ArrayList; import java.util.List; import java.util.concurrent.ExecutionException; import org.json.JSONException; import org.json.JSONObject; import android.app.ActionBar; import android.content.Intent; import android.graphics.Color; import android.graphics.drawable.ColorDrawable; import android.os.AsyncTask; import android.os.Bundle; import android.support.v4.app.FragmentActivity; import android.support.v4.app.FragmentManager; import android.support.v4.app.FragmentTabHost; import android.support.v4.app.FragmentTransaction; import android.support.v4.view.ViewPager; import android.text.Html; import android.util.Log; import android.view.Menu; import android.view.MenuInflater; import android.view.Window; import android.widget.TabHost.OnTabChangeListener; import android.widget.TextView; import com.facebook.Session; import com.google.gson.Gson; import com.stalker.adapters.ViewPagerAdapter; import com.stalker.objects.HomeSliderClassForAdapter; import com.stalker.objects.LikeCategorySummaryResult; import com.stalker.objects.StoryResult; import com.stalker.objects.eStoryType; public class ProfileActivity extends FragmentActivity { AsyncTask StoryResponse; public String storyResponseString; TextView tv; public String UserId; String UserName; String AccessToken; ViewPager VPSlider; public LikeCategorySummaryResult interestResult; FragmentTabHost mTabHost; StoryResult Stories = new StoryResult(); @Override protected void onCreate(Bundle savedInstanceState) { // TODO Auto-generated method stub super.onCreate(savedInstanceState); setContentView(R.layout.activity_profile); VPSlider = (ViewPager) findViewById(R.id.VPSlider); // ///////////////////////// mTabHost = (FragmentTabHost) findViewById(android.R.id.tabhost); mTabHost.setup(this, getSupportFragmentManager(), android.R.id.tabcontent); mTabHost.addTab( mTabHost.newTabSpec("tab1").setIndicator( getResources().getString(R.string.interest)), InterestTabFragment.class, null); mTabHost.addTab( mTabHost.newTabSpec("tab2").setIndicator( getResources().getString(R.string.interaction)), InteractionTabFragment.class, null); mTabHost.addTab( mTabHost.newTabSpec("tab3").setIndicator( getResources().getString(R.string.hangout)), HangoutTabFragment.class, null); mTabHost.setOnTabChangedListener(new OnTabChangeListener() { @Override public void onTabChanged(String tabId) { // TODO Auto-generated method stub FragmentManager fragmentManager = getSupportFragmentManager(); InterestTabFragment tabOneFrgment = (InterestTabFragment) fragmentManager .findFragmentByTag("tab1"); InteractionTabFragment tabTwoFrgment = (InteractionTabFragment) fragmentManager .findFragmentByTag("tab2"); HangoutTabFragment tabThreeFrgment = (HangoutTabFragment) fragmentManager .findFragmentByTag("tab3"); FragmentTransaction fragmentTransaction = fragmentManager .beginTransaction(); if (tabId.equalsIgnoreCase("tab1")) { if (tabOneFrgment != null) { if (tabTwoFrgment != null) { fragmentTransaction.hide(tabTwoFrgment); } if (tabThreeFrgment != null) { fragmentTransaction.hide(tabThreeFrgment); } fragmentTransaction.show(tabOneFrgment); } } else if (tabId.equalsIgnoreCase("tab2")) { if (tabTwoFrgment != null) { if (tabOneFrgment != null) { fragmentTransaction.hide(tabOneFrgment); } if (tabThreeFrgment != null) { fragmentTransaction.hide(tabThreeFrgment); } fragmentTransaction.show(tabTwoFrgment); } } else { if (tabThreeFrgment != null) { if (tabOneFrgment != null) { fragmentTransaction.hide(tabOneFrgment); } if (tabTwoFrgment != null) { fragmentTransaction.hide(tabTwoFrgment); } fragmentTransaction.show(tabThreeFrgment); } } fragmentTransaction.commit(); } }); Session session = Session.getActiveSession(); if (session != null && session.isOpened()) { // Get the user's data AccessToken = session.getAccessToken(); makeStoriesRequest(session); } } @Override public boolean onCreateOptionsMenu(Menu menu) { MenuInflater inflater = getMenuInflater(); inflater.inflate(R.menu.stalker_profile_menu, menu); return true; } private void makeStoriesRequest(final Session session) { String URL = "http://..../"; JSONObject UserStory; JSONObject ProfileStoryString = new JSONObject(); StoryResponse = new RequestTask().execute(URL); try { storyResponseString = StoryResponse.get(); UserStory = new JSONObject(storyResponseString); ProfileStoryString = UserStory.getJSONObject("StoryResult"); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (ExecutionException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (JSONException e) { // TODO Auto-generated catch block e.printStackTrace(); } try { Gson gson = new Gson(); try { // j = new JSONObject(responseString); Stories = gson.fromJson(ProfileStoryString.toString(), StoryResult.class); } catch (Exception e) { Log.i("my", e.getMessage()); e.printStackTrace(); } } catch (Throwable t) { Log.e("My App", "Could not parse malformed JSON: \"" + storyResponseString + "\"" + t.getMessage()); } ViewPagerAdapter adapter = new ViewPagerAdapter(this, getSlider()); VPSlider.setAdapter(adapter); } @Override protected void onResumeFragments() { super.onResumeFragments(); } } 

我有这个片段活动，我正在显示标签。 我有三个标签。 现在我只在InterestTabFragment.java中添加了代码

 package com.stalker.androidapp; import java.util.concurrent.ExecutionException; import org.json.JSONException; import org.json.JSONObject; import android.os.AsyncTask; import android.os.Bundle; import android.support.v4.app.Fragment; import android.util.Log; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import com.devsmart.android.ui.HorizontalListView; import com.facebook.Session; import com.google.gson.Gson; import com.stalker.adapters.CategoryLVAdapter; import com.stalker.objects.LikeCategorySummaryResult; public class InterestTabFragment extends Fragment{ View view; String access_token; AsyncTask FirstResponse; public String responseString; JSONObject joiningYear; HorizontalListView listview; @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { // TODO Auto-generated method stub super.onCreateView(inflater, container, savedInstanceState); view = inflater.inflate(R.layout.interest_tab_fragment, container, false); listview = (HorizontalListView) view.findViewById(R.id.LVCategory); Session session = Session.getActiveSession(); if (session != null && session.isOpened()) { // Get the user's data access_token = session.getAccessToken(); makeInterestRequest(session); } return view; } private void makeInterestRequest(final Session session) { access_token = session.getAccessToken(); String URL = "http://..."; JSONObject HomeCardString = new JSONObject(); FirstResponse = new RequestTask().execute(URL); try { responseString = FirstResponse.get(); joiningYear = new JSONObject(responseString); HomeCardString = joiningYear.getJSONObject("LikeCategorySummaryResult"); // HomeCardString = TestApiResult.getJSONObject("UserHomeResult"); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (ExecutionException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (JSONException e) { // TODO Auto-generated catch block e.printStackTrace(); } try { Gson gson = new Gson(); try { // j = new JSONObject(responseString); ((ProfileActivity)getActivity()).interestResult = gson.fromJson(HomeCardString.toString(), LikeCategorySummaryResult.class); } catch(Exception e) { Log.i("myyyy", e.getMessage()); e.printStackTrace(); } } catch (Throwable t) { Log.e("My App", "Could not parse malformed JSON: \"" + responseString + "\"" + t.getMessage()); } CategoryLVAdapter adapter = new CategoryLVAdapter(getActivity(), R.layout.category_item_template, ((ProfileActivity)getActivity()).interestResult.categories); listview.setAdapter(adapter); // listView.setAdapter(adapter); } } 

这段代码工作正常。 但是当我转到我的第二个标签然后返回第一个标签。 它再次加载数据。 但我希望它只是显示以前的片段不再加载它。

链接到一个很好的教程也会有所帮助，但我已经按照本教程，但它没有工作，因为我期望它工作。

Answer 1

如果你转到第3个标签然后转到第2个或第1个标签，则会重新创建第1个并调用onCreate，这是片段的默认行为。 但是转到第二个选项卡然后返回第一个选项卡将不会重新创建第一个选项卡。 我仅在onCreate中对InterestTabFragment.java进行了一些更改。 看看是否有帮助，如果没有，请通知我，我可以再试一次。 谢谢…..

 public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { // TODO Auto-generated method stub super.onCreateView(inflater, container, savedInstanceState); view = inflater.inflate(R.layout.interest_tab_fragment, container, false); listview = (HorizontalListView) view.findViewById(R.id.LVCategory); if(((ProfileActivity)getActivity()).interestResult.categories == null){ Session session = Session.getActiveSession(); if (session != null && session.isOpened()) { // Get the user's data access_token = session.getAccessToken(); makeInterestRequest(session); } } else { CategoryLVAdapter adapter = new CategoryLVAdapter(getActivity(), R.layout.category_item_template, ((ProfileActivity)getActivity()).interestResult.categories); listview.setAdapter(adapter); } return view; }