Question

我有一个托管viewpager的Tabbed Activity（使用eclipse向导自动生成）。我稍微修改了自动生成的FragmentPagerAdapter，以便在每个选项卡上实例化特定的片段。最初我有4个选项卡，3个片段用于第一个选项卡，并且仍然是最后一个自动生成的占位符，并且它们有效。当我用我的一个Fragment的实例替换最后一个占位符时，我面临以下问题：最后两个选项卡之一中的片段保持空白，如下所示：

_____ 1st TAB ___ | ____ 2nd TAB_ | ___ 3rd TAB _____ | ____ 4th TAB ____ |

[MasterFragment] [RequestMap] [MasterFragment] [MasterFragment]

这是空白_____________________ |

此外，如果我制作一个“随机”动作序列（更改标签，点击按钮执行某些操作，......）未显示交换的片段，并成为最后一个如下：

_____ 1st TAB ___ | ____ 2nd TAB_ | ___ 3rd TAB _____ | ____ 4th TAB ____ |

[MasterFragment] [RequestMap] [MasterFragment] [MasterFragment]

这是空白__________________________________ |

这是我的FragmentPagerAdapter的代码：

public class SectionsPagerAdapter extends FragmentPagerAdapter {

    public SectionsPagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public Fragment getItem(int position) {
        switch (position) {
        case REQUEST_TAB:
            masterFragment = new MasterFragment(MasterFragment.ALL_REQUEST);
            return masterFragment;
        case MAP_TAB:
            requestMap = new RequestMap();
            return requestMap;
        case OWNER_TAB:
            masterFragmentOwner = new MasterFragment(MasterFragment.OWNER_REQUEST);
            System.out.println("I should have created the Owner MasterFragment");
            return masterFragmentOwner;
        case JOINED_TAB:
            masterFragmentJoined = new MasterFragment(MasterFragment.JOINED_REQUEST);
            return masterFragmentJoined;
        }
        return null;
    }

    @Override
    public int getCount() {
        return 4;
    }

    @Override
    public CharSequence getPageTitle(int position) {
        Locale l = Locale.getDefault();
        switch (position) {
        case REQUEST_TAB:
            return getString(R.string.request_tab_title).toUpperCase(l);
        case MAP_TAB:
            return getString(R.string.map_tab_title).toUpperCase(l);
        case OWNER_TAB:
            return getString(R.string.owner_tab_title).toUpperCase(l);
        case JOINED_TAB:
            return getString(R.string.joined_tab_title).toUpperCase(l);
        default:
            return "";
        }
    }
}

我省略了有关viewPager设置的代码，因为它是从eclipse向导生成的相同内容。虽然这是MasterFragment类的代码：

package it.polimi.frontend.fragment;

import it.polimi.appengine.entity.manager.model.Request;
import it.polimi.appengine.entity.manager.model.User;
import it.polimi.frontend.activity.R;
import it.polimi.frontend.util.QueryManager;
import it.polimi.frontend.util.QueryManager.OnRequestLoadedListener;

import java.util.ArrayList;
import java.util.List;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.view.InflateException;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class MasterFragment extends Fragment implements OnRequestLoadedListener, RequestList.OnRequestSelectedListener, RequestDetail.OnUserClickedListener{

private boolean twoPane;
private static View view;
public final static int ALL_REQUEST=0;
public final static int OWNER_REQUEST=1;
public final static int JOINED_REQUEST=2;
private int mode;

public MasterFragment(){
    this.mode=0;
}
public MasterFragment(int mode){
    this.mode=mode;
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    QueryManager.getInstance().addListener(this);
    if (view != null) {
        ViewGroup parent = (ViewGroup) view.getParent();
        if (parent != null)
            parent.removeView(view);
    }
    try {
        view = inflater.inflate(R.layout.fragment_master,container, false);
        List<Request> requests = new ArrayList<Request>();
        RequestList requestListFragment = null;
        switch (mode) {
        case OWNER_REQUEST:
            requests = QueryManager.getInstance().getCurrentUser().getRequests();
            System.out.println("Dovrei aver recuperato le richieste dell'owner");
            break;
        case JOINED_REQUEST:
            String mail=null;
            if (QueryManager.getInstance().getCurrentUser()!=null){
                User current =QueryManager.getInstance().getCurrentUser();
                mail = current.getPwAccount() != null ? 
                        current.getPwAccount()
                        : current.getGmailAccount() != null ?
                                current.getGmailAccount() 
                                : current.getFbAccount() != null ?
                                        current.getFbAccount()
                                        : null;
                requests = QueryManager.getInstance().getUserPartecipation(mail);
            }
            else
                requests = new ArrayList<Request>();
            break;
        default: //ALL_REQUEST case and all the other possibilities
            requests = QueryManager.getInstance().getRequests();
            break;
        }
        requestListFragment = new RequestList(requests, mode);
        if (view.findViewById(R.id.detail_container) != null) {//TABLET CASE
            twoPane = true;
            getChildFragmentManager().beginTransaction()
            .replace(R.id.request_list_container,requestListFragment,RequestList.ID)
            .commit();

        } else { //PHONE CASE:
            getChildFragmentManager().beginTransaction()
            .replace(R.id.container,requestListFragment,RequestList.ID)
            .commit();
        }
    } catch (InflateException e) {
        // is already there, just return view as it is
        e.printStackTrace();
    }
    return view;
}

@Override
public void onRequestSelected(int position, Request request) {
    if (twoPane) {
        DetailContainerFragment detailContFrag = new DetailContainerFragment(request,mode);
        getChildFragmentManager().beginTransaction()
        .replace(R.id.detail_container, detailContFrag, DetailContainerFragment.ID).commit();
    } else {
        switch (mode) {//This empty switch if for future changes
        case OWNER_REQUEST:
            break;
        case JOINED_REQUEST:
            break;
        default://ALL_REQUEST               
            break;
        }
        RequestDetail fragment = new RequestDetail(request,mode);
        Fragment reqList=getChildFragmentManager().findFragmentByTag(RequestList.ID);

        getChildFragmentManager().beginTransaction()
        .hide(reqList)
        .addToBackStack(RequestDetail.ID)
        .add(R.id.container,fragment,RequestDetail.ID)
        .commit();
    }
}

@Override
public void onUserClicked(User user,String requestId) {
    if (!twoPane) {
        FeedbackDetail fragment = new FeedbackDetail(user,this.mode,requestId);
        Fragment reqDetail=getChildFragmentManager().findFragmentByTag(RequestDetail.ID);

        getChildFragmentManager().beginTransaction()
        .hide(reqDetail)
        .addToBackStack(FeedbackDetail.ID)
        .add(R.id.container,fragment,FeedbackDetail.ID)
        .commit();

    } else {
        /*DetailContainerFragment should take care of it*/
    }
}
@Override
public void onRequestLoaded(List<Request> requests) {
    System.out.println("Ho caricato: "+requests.size());
    RequestList requestListFragment = (RequestList)getChildFragmentManager().findFragmentByTag(RequestList.ID);
    switch (mode) {//Also this switch is for future changes, but the requests list is anyway fetched and assigned to RequestList above
    case OWNER_REQUEST:
        //TODO
        break;
    case JOINED_REQUEST:
        //TODO
        break;
    default: //ALL_REQUEST
        if (requestListFragment!=null)
            requestListFragment.setRequestAdapter(requests);
        break;
    }
}

}

如果我遗漏了重要的事，请告诉我。提前谢谢大家

编辑：我忘了说我放置的System.out出现在控制台中，所以应该创建“空白”片段，它应该已经通过他的onCreateView（）。

Answer 1

我发现了这个错误。问题是

private static View view;

因为静态属性。删除“静态”它再次起作用。实际上我甚至无法解释它如何在第一个和最后一个选项卡上工作一段时间而不是第三个选项卡，因为静态属性应该在类的所有实例之间共享。由于ViewPager的内部，问题似乎只出现在相邻的相同MasterFragment上，如果它们与其工作的任何其他片段交错。

ViewPager中的一个片段不会显示

1 个答案: