android - 查看页面 : If page get removed the next pages content gets the removed pages content

Question

(如果有人需要更多信息或更好的描述，请告诉我)

您好，我从这里添加了 viewPagerLibrary:http://viewpagerindicator.com/#introduction今天在我的项目中。

不，我遇到了一个非常奇怪的问题: 如果我添加一个网站或页面(让我们在接下来的几行中称它为网站)并再次删除它，一切都很好。但是，如果我尝试添加一个不同的页面(这些页面是实现 BaseFragment 类的不同 Fragements)，则会显示第一页的内容。 如果我添加几页并删除这些页面之间的一页，也会发生同样的事情。被删除页面之后的页面现在显示被删除页面的内容。

此错误的示例: 现在的问题是。如果我在 FragmentB 之后添加 FragmentA，然后我删除 FragmentA，FragmentB 获取 FragmentA 的 View /内容。奇怪的是，对象是正确的(因此适配器返回正确的对象)并且标题也是正确的。

在我的 main 中，我以这种方式创建我的寻呼机、指示器和适配器:

    Cfg.mAdapter = new FragmentAdapter(getSupportFragmentManager());

    Cfg.mPager = (ViewPager)findViewById(R.id.pager);
    Cfg.mPager.setAdapter(Cfg.mAdapter);

    Cfg.mIndicator = (TabPageIndicator)findViewById(R.id.indicator);
    Cfg.mIndicator.setViewPager(Cfg.mPager);

    //We set this on the indicator, NOT the pager
    Cfg.mIndicator.setOnPageChangeListener(TabHelper.onPageChangeListener);

(Cfg是一个静态文件，用来存储那些东西以供使用)

我的 BaseFragment 如下所示:

public class BaseFragment extends Fragment{

    public static int FILE_FRAGMENT = 0;
    public static int FTP_FRAGMENT = 1;
    public static int ADDFTP_FRAGMENT = 2;
    public static int PREVIEW_FRAGMENT = 3;
    public static int CSS_FRAGMENT = 4;
    public static int BOOKS_FRAGMENT = 5;
    public static int SNIPPETS_FRAGMENT = 6;

    //private int id;
    private int typ;
    private String title;

    public int getTyp() {
        return typ;
    }

    public void setTyp(int typ) {
        this.typ = typ;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }
}

其中一个 fragment 看起来像这样(我认为其他 fragment 没有区别):

public class FtpFragment extends BaseFragment {
    private static RowLayout rowLayout_view;

    public FtpFragment() {
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        init_data();
    }

    public static void init_data()
    {
        //Remove child for update
        rowLayout_view.removeAllViews();

        List<FtpData> ftps = FtpStorage.getInstance().getFtps();

        if (ftps != null) {
            for (FtpData f : ftps) {
                View inflatedView;
                inflatedView = View.inflate(Cfg.ctx, R.layout.ftp, null);
                inflatedView.setOnClickListener(button_ftp_listener);
                inflatedView.setOnLongClickListener(button_ftp_longClickListener);
                inflatedView.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, Converter.convertFromDPtoPixel(160.0f)));
                inflatedView.setTag(f);
                inflatedView.findViewById(R.id.book_imageview).setBackgroundDrawable(
                                Cfg.ctx.getResources().getDrawable(R.drawable.nopreview));


                ((TextView) inflatedView.findViewById(R.id.book_textview)).setText(f.nickname);

                rowLayout_view.addView(inflatedView);
            }
        }
    }

    @Override

public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View v = inflater.inflate(R.layout.fragment_ftp, container, false);
    rowLayout_view = (RowLayout) v.findViewById(R.id.rowLayout_ftps);
    return v;
}

@Override
public String getTitle() {
    return "FTPs";
}

@Override
public int getTyp() {
    return BaseFragment.FTP_FRAGMENT;
}

@Override
public void setTyp(int typ) {
    super.setTyp(typ);
}

要删除或添加一个页面，我称之为:

public static void addNewTab(BaseFragment fragment)
{
    Cfg.mAdapter.addItem(fragment);
    Cfg.mPager.setCurrentItem(Cfg.mAdapter.getCount());
    Cfg.mIndicator.notifyDataSetChanged();
}

public static void deleteActTab()
{
    Cfg.mAdapter.removeItem(Cfg.mAdapter.getActPage());
    Cfg.mIndicator.notifyDataSetChanged();
}

那是适配器:

public class FragmentAdapter extends FragmentPagerAdapter implements TitleProvider{
    public List<BaseFragment> fragments = new LinkedList<BaseFragment>();

    private int actPage;

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


    public void setActPage(int actPage) {
        Lg.d("setActPage: " + actPage + " : " + fragments.get(actPage).toString());
        this.actPage = actPage; 
    }

    public void addItem(BaseFragment fragment)
    {
        Lg.d("addItem: " + fragment.toString());
        fragments.add(fragment);
    }

    public void removeItem(int index)
    {
        if(index < getCount()){
            Lg.d("RemoveItem: " + index + " : " + fragments.get(index).toString());
            fragments.remove(index);
        }
    }

    public BaseFragment getActFragment()
    {
        return getItem(getActPage());
    }

    public int getActPage() {
        return actPage;
    }

    @Override
    public BaseFragment getItem(int position) {
        if(position < getCount())
        {
            Lg.v("getItem: " + fragments.get(position));
            return fragments.get(position);
        }
        else
            return null;
    }

    @Override
    public int getCount() {
        return fragments.size();
    }

    @Override
    public String getTitle(int position) {
        Lg.v("Get Title: " + fragments.get(position).getTitle());
        return fragments.get(position).getTitle();
    }

}

是的，我希望有人能帮助我。

如果我忘记了什么，请告诉我。

提前致谢， 迈克

Answer 1

好吧，我现在已经以一种骇人听闻的方式解决了我的问题，但是它确实有效 ;)。如果有人可以改进我的解决方案，请告诉我。对于我的新解决方案，我现在使用 CustomFragmentStatePagerAdapter 但它不会像它应该的那样保存状态并将所有 fragment 存储在列表中。如果用户有超过 50 个 fragment ，这可能会导致内存问题，就像普通的 FragmentPagerAdapter 一样。如果有人可以在不删除我的修复程序的情况下将状态事物添加回我的解决方案，那就太好了。谢谢。

这是我的CustomFragmentStatePagerAdapter.java

package com.tundem.webLab.Adapter;

import java.util.ArrayList;

import android.os.Bundle;
import android.os.Parcelable;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.support.v4.view.PagerAdapter;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;

public abstract class CustomFragmentStatePagerAdapter extends PagerAdapter {
    private static final String TAG = "FragmentStatePagerAdapter";
    private static final boolean DEBUG = false;

    private final FragmentManager mFragmentManager;
    private FragmentTransaction mCurTransaction = null;

    public ArrayList<Fragment.SavedState> mSavedState = new ArrayList<Fragment.SavedState>();
    public ArrayList<Fragment> mFragments = new ArrayList<Fragment>();
    private Fragment mCurrentPrimaryItem = null;

    public CustomFragmentStatePagerAdapter(FragmentManager fm) {
        mFragmentManager = fm;
    }

    /**
     * Return the Fragment associated with a specified position.
     */
    public abstract Fragment getItem(int position);

    @Override
    public void startUpdate(ViewGroup container) {}

    @Override
    public Object instantiateItem(ViewGroup container, int position) {
        // If we already have this item instantiated, there is nothing
        // to do. This can happen when we are restoring the entire pager
        // from its saved state, where the fragment manager has already
        // taken care of restoring the fragments we previously had instantiated.

        // DONE Remove of the add process of the old stuff
        /* if (mFragments.size() > position) { Fragment f = mFragments.get(position); if (f != null) { return f; } } */

        if (mCurTransaction == null) {
            mCurTransaction = mFragmentManager.beginTransaction();
        }

        Fragment fragment = getItem(position);
        if (DEBUG)
            Log.v(TAG, "Adding item #" + position + ": f=" + fragment);
        if (mSavedState.size() > position) {
            Fragment.SavedState fss = mSavedState.get(position);
            if (fss != null) {
                try // DONE: Try Catch
                {
                    fragment.setInitialSavedState(fss);
                } catch (Exception ex) {
                    // Schon aktiv (kA was das heißt xD)
                }
            }
        }
        while (mFragments.size() <= position) {
            mFragments.add(null);
        }
        fragment.setMenuVisibility(false);
        mFragments.set(position, fragment);
        mCurTransaction.add(container.getId(), fragment);

        return fragment;
    }

    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        Fragment fragment = (Fragment) object;

        if (mCurTransaction == null) {
            mCurTransaction = mFragmentManager.beginTransaction();
        }
        mCurTransaction.remove(fragment);

        /*if (mCurTransaction == null) { mCurTransaction = mFragmentManager.beginTransaction(); } if (DEBUG) Log.v(TAG, "Removing item #" + position + ": f=" + object + " v=" + ((Fragment)
         * object).getView()); while (mSavedState.size() <= position) { mSavedState.add(null); } mSavedState.set(position, mFragmentManager.saveFragmentInstanceState(fragment));
         * mFragments.set(position, null); mCurTransaction.remove(fragment); */
    }

    @Override
    public void setPrimaryItem(ViewGroup container, int position, Object object) {
        Fragment fragment = (Fragment) object;
        if (fragment != mCurrentPrimaryItem) {
            if (mCurrentPrimaryItem != null) {
                mCurrentPrimaryItem.setMenuVisibility(false);
            }
            if (fragment != null) {
                fragment.setMenuVisibility(true);
            }
            mCurrentPrimaryItem = fragment;
        }
    }

    @Override
    public void finishUpdate(ViewGroup container) {
        if (mCurTransaction != null) {
            mCurTransaction.commitAllowingStateLoss();
            mCurTransaction = null;
            mFragmentManager.executePendingTransactions();
        }
    }

    @Override
    public boolean isViewFromObject(View view, Object object) {
        return ((Fragment) object).getView() == view;
    }

    @Override
    public Parcelable saveState() {
        Bundle state = null;
        if (mSavedState.size() > 0) {
            state = new Bundle();
            Fragment.SavedState[] fss = new Fragment.SavedState[mSavedState.size()];
            mSavedState.toArray(fss);
            state.putParcelableArray("states", fss);
        }
        for (int i = 0; i < mFragments.size(); i++) {
            Fragment f = mFragments.get(i);
            if (f != null) {
                if (state == null) {
                    state = new Bundle();
                }
                String key = "f" + i;
                mFragmentManager.putFragment(state, key, f);
            }
        }
        return state;
    }

    @Override
    public void restoreState(Parcelable state, ClassLoader loader) {
        if (state != null) {
            Bundle bundle = (Bundle) state;
            bundle.setClassLoader(loader);
            Parcelable[] fss = bundle.getParcelableArray("states");
            mSavedState.clear();
            mFragments.clear();
            if (fss != null) {
                for (int i = 0; i < fss.length; i++) {
                    mSavedState.add((Fragment.SavedState) fss[i]);
                }
            }
            Iterable<String> keys = bundle.keySet();
            for (String key : keys) {
                if (key.startsWith("f")) {
                    int index = Integer.parseInt(key.substring(1));
                    Fragment f = mFragmentManager.getFragment(bundle, key);
                    if (f != null) {
                        while (mFragments.size() <= index) {
                            mFragments.add(null);
                        }
                        f.setMenuVisibility(false);
                        mFragments.set(index, f);
                    } else {
                        Log.w(TAG, "Bad fragment at key " + key);
                    }
                }
            }
        }
    }
}

这是我的正常 FragmentAdapter.java

package com.tundem.webLab.Adapter;

import java.util.LinkedList;
import java.util.List;

import android.support.v4.app.FragmentManager;

import com.tundem.webLab.fragments.BaseFragment;
import com.viewpagerindicator.TitleProvider;

public class FragmentAdapter extends CustomFragmentStatePagerAdapter implements TitleProvider {
    public List<BaseFragment> fragments = new LinkedList<BaseFragment>();

    private int actPage;

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

    public void setActPage(int actPage) {
        this.actPage = actPage;
    }

    public void addItem(BaseFragment fragment) {
        // TODO if exists don't open / change to that tab
        fragments.add(fragment);
    }

    public BaseFragment getActFragment() {
        return getItem(getActPage());
    }

    public int getActPage() {
        return actPage;
    }

    @Override
    public BaseFragment getItem(int position) {
        if (position < getCount()) {
            return fragments.get(position);
        } else
            return null;
    }

    @Override
    public int getCount() {
        return fragments.size();
    }

    @Override
    public String getTitle(int position) {
        return fragments.get(position).getTitle();
    }

    @Override
    public int getItemPosition(Object object) {
        return POSITION_NONE;
    }
}

这就是我删除 fragment 的方式。 (我知道它不仅仅是 .remove() )。可以自由地改进我的解决方案，您也可以在适配器中的某处添加此代码，是的。这取决于尝试实现它的用户。我在我的 TabHelper.java(一个处理所有选项卡操作的类，如删除、添加...)中使用它

    int act = Cfg.mPager.getCurrentItem();
    Cfg.mPager.removeAllViews();
    Cfg.mAdapter.mFragments.remove(act);
    try {
        Cfg.mAdapter.mSavedState.remove(act);
    } catch (Exception ex) {/* Already removed */}
    try {
        Cfg.mAdapter.fragments.remove(act);
    } catch (Exception ex) {/* Already removed */}

    Cfg.mAdapter.notifyDataSetChanged();
    Cfg.mIndicator.notifyDataSetChanged();

Cfg 的描述。事物。我将对这些对象的引用保存在 cfg 类中，这样我就可以随时使用它们而无需特殊的 Factory.java ...

是的。我希望我能提供帮助。随时改进它，但让我知道，这样我也可以改进我的代码。

谢谢。

如果我遗漏了任何代码，请告诉我。

---

我的旧答案也有效，但前提是您有不同的 fragment 。 FileFragment、WebFragment、... 如果您两次使用其中一种 fragment 类型，则不会。

我现在让它伪工作了。这是一个非常肮脏的解决方案，我仍在寻找更好的解决方案。请帮忙。

我更改了代码，删除了这个标签:

   public static void deleteActTab()
        {   
            //We set this on the indicator, NOT the pager
            int act = Cfg.mPager.getCurrentItem();
            Cfg.mAdapter.removeItem(act);
            List<BaseFragment> frags = new LinkedList<BaseFragment>();
            frags = Cfg.mAdapter.fragments;

            Cfg.mPager = (ViewPager)Cfg.act.findViewById(R.id.pager);
            Cfg.mPager.setAdapter(Cfg.mAdapter);
            Cfg.mIndicator.setViewPager(Cfg.mPager);

            Cfg.mAdapter.fragments = frags;

            if(act > 0)
            {
                Cfg.mPager.setCurrentItem(act-1);
                Cfg.mIndicator.setCurrentItem(act-1);
            }

            Cfg.mIndicator.notifyDataSetChanged();
        }

如果有人可以改进此代码，请告诉我。如果有人可以告诉我们该问题的真正答案。请在此处添加。有很多人遇到过这个问题。我为解决它的人增加了 50 的声誉。我也可以为解决问题的人捐款。

谢谢