鏡像複選框與Android的不同片段狀態

Question

我正在開發應用程序，該應用程序應該顯示會議的會話列表，而另一個列表僅包含會議的文件。

我貼幾張截圖這樣一個問題：Save checkboxes states through fragments in Android

我的目標是能夠也«鏡»的複選框狀態在兩個列表，這樣，如果紙張在會談名單核對，它在論文列表中被檢查。

你有什麼想法我可以做到這一點？

該列表是使用兩個片段與自己的適配器實現的。

這裏是我的代碼：

主要活動：

package be.unamur.confpers; 
public class MainActivity extends FragmentActivity implements ActionBar.TabListener { 

private ViewPager viewPager; 
private TabsPagerAdapter mAdapter; 
private ActionBar actionBar; 
SqlHandler sqlHandler; 
// Tab titles 
private String[] tabs = { "Talks", "Papers", "Ma sélection"}; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 

    // Initialization database 
    sqlHandler = new SqlHandler(this); 

    viewPager = (ViewPager) findViewById(R.id.pager); 
    actionBar = getActionBar(); 
    mAdapter = new TabsPagerAdapter(getSupportFragmentManager()); 

    viewPager.setAdapter(mAdapter); 
    actionBar.setHomeButtonEnabled(false); 
    actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);  

    // Adding Tabs 
    for (String tab_name : tabs) { 
     actionBar.addTab(actionBar.newTab().setText(tab_name) 
       .setTabListener(this)); 
    } 

    /** 
    * on swiping the viewpager make respective tab selected 
    * */ 
    viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() { 

     @Override 
     public void onPageSelected(int position) { 
      // on changing the page 
      // make respected tab selected 
      actionBar.setSelectedNavigationItem(position); 
     } 

     @Override 
     public void onPageScrolled(int arg0, float arg1, int arg2) { 
     } 

     @Override 
     public void onPageScrollStateChanged(int arg0) { 
     } 
    }); 
} 

@Override 
public void onTabReselected(Tab tab, FragmentTransaction ft) { 
} 

@Override 
public void onTabSelected(Tab tab, FragmentTransaction ft) { 
    // on tab selected 
    // show respected fragment view 
    viewPager.setCurrentItem(tab.getPosition()); 
} 

@Override 
public void onTabUnselected(Tab tab, FragmentTransaction ft) { 
} 



} 

TalksFragment：

public class TalksFragment extends Fragment { 

private TalkAdapter talkAdapter; 
List<Talk> talks; 

private List<Talk> talksParser(){ 

    try{ 
     XMLParser parser = new XMLParser(); 
     talks = parser.parse(getActivity().getApplicationContext().getAssets().open("talks.xml")); 
    } catch (IOException e) { 
     // TODO Auto-generated catch block 
     e.printStackTrace(); 
    } 

    return talks; 
}; 


@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container, 
     Bundle savedInstanceState) { 

    View v = inflater.inflate(R.layout.fragment_talks, container, false); 

    ExpandableListView lv = (ExpandableListView) v.findViewById(R.id.listTalks); 
    talks = talksParser(); 
    talkAdapter = new TalkAdapter (getActivity(),talks); 
    lv.setAdapter(talkAdapter); 


    return v; 
} 
} 

TalkAdapter：

public class TalkAdapter extends BaseExpandableListAdapter { 

private Context context; 
private List<Talk> talks; 
private LayoutInflater inflater; 
private Button changeScreen; 

int checked = 0; 
CheckBox cb; 



public TalkAdapter(Context context, 
     List<Talk> talks) { 
    this.context = context; 
    this.talks = talks; 
    inflater = LayoutInflater.from(context); 
} 

public Paper getChild(int groupPosition, int childPosition) { 
    return talks.get(groupPosition).getPapers().get(childPosition); 
} 

public long getChildId(int groupPosition, int childPosition) { 
    return (long)(groupPosition*1024+childPosition); // Max 1024 children per group 
} 

private class ViewHolder { 
    TextView title; 
    TextView author; 
    CheckBox name; 
} 


public View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent) { 
    View v = null; 
    ViewHolder holder = null; 

    if(convertView == null){ 
     v = inflater.inflate(R.layout.child_row, parent, false); 
     Paper p = getChild(groupPosition, childPosition); 

     cb = (CheckBox)v.findViewById(R.id.check1); 
     //cb.setChecked(p.getState()); 

     TextView paper = (TextView)v.findViewById(R.id.papername); 
     if(paper != null) 
      paper.setText(p.getTitle()); 

     TextView author = (TextView)v.findViewById(R.id.authorname); 
     if(author!= null) 
      author.setText(p.getAuthor()); 

     holder = new ViewHolder(); 
     holder.name = (CheckBox) v.findViewById(R.id.check1); 
     holder.title = (TextView) v.findViewById(R.id.papername); 
     holder.author= (TextView) v.findViewById(R.id.authorname); 
     v.setTag(holder); 

     holder.name.setOnClickListener(new View.OnClickListener() { 

      public void onClick(View v) { 
       // TODO Auto-generated method stub 
       CheckBox cb = (CheckBox) v; 
       Paper paper = (Paper) cb.getTag(); 
       String title = paper.getTitle(); 
       String author = paper.getAuthor(); 
       if (cb.isChecked()){ 
        Toast.makeText(context, "Papier "+title+ " ajouté", Toast.LENGTH_SHORT).show(); 
        //String query = "INSERT INTO SELECTED_PAPERS(title,author) values ('" 
        //+ title +"','" + author +"')"; 
        //sqlHandler.executeQuery(query); 

       } 
       if (cb.isChecked()==false){ 
        Toast.makeText(context, "Papier "+title+ " retiré", Toast.LENGTH_SHORT).show(); 
       } 
      } 
     }); 
    } 

    else{ 
     v = convertView; 
     holder = (ViewHolder) v.getTag(); 
    } 

    Paper paper = getChild(groupPosition, childPosition); 
    holder.author.setText(paper.getAuthor()); 
    holder.title.setText(paper.getTitle()); 
    holder.name.setTag(paper); 

    return v; 


} 

public int getChildrenCount(int groupPosition) { 
    return talks.get(groupPosition).getPapers().size(); 
} 

public Talk getGroup(int groupPosition) { 
    return talks.get(groupPosition);   
} 

public int getGroupCount() { 
    return talks.size(); 
} 

public long getGroupId(int groupPosition) { 
    return (long)(groupPosition*1024); // To be consistent with getChildId 
} 

public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) { 
    View v = null; 
    if(convertView != null) 
     v = convertView; 
    else 
     v = inflater.inflate(R.layout.group_row, parent, false); 
    Talk t = getGroup(groupPosition); 
    TextView colorGroup = (TextView)v.findViewById(R.id.papername); 
    if(t != null) 
     colorGroup.setText(t.getName()); 


    return v; 
} 



public boolean hasStableIds() { 
    return true; 
} 

public boolean isChildSelectable(int groupPosition, int childPosition) { 
    return true; 
} 

public void onGroupCollapsed (int groupPosition) {} 
public void onGroupExpanded(int groupPosition) {} 


} 

PapersFragment：

public class PapersFragment extends Fragment { 

private PaperAdapter listAdapter; 
private Context myContext; 
List<Paper> papers = null; 




private List<Paper> papersParser() { 

    try { 
     XMLParser2 parser = new XMLParser2(); 
     papers = parser.parse(getActivity().getApplicationContext().getAssets().open("talks.xml")); 
    } catch (IOException e) { 
     // TODO Auto-generated catch block 
     e.printStackTrace(); 
    } 

    return papers; 
}; 



@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container, 
     Bundle savedInstanceState) { 

    View v = inflater.inflate(R.layout.fragment_papers, container, false); 

    ListView lv = (ListView) v.findViewById(R.id.list); 
    papers = papersParser(); 
    listAdapter = new PaperAdapter(getActivity(),papers); 
    lv.setAdapter(listAdapter); 
    lv.setOnItemClickListener(new OnItemClickListener(){ 
     public void onItemClick(AdapterView<?> parent, View view, 
       int position, long id) { 
      //Si un jour je veux mettre une description 
        } 
    }); 

    if (papers == null) { 
    Toast.makeText(getActivity().getApplicationContext(), "Papers vide", Toast.LENGTH_LONG).show(); 
    } 
    return v; 
} 
} 

PaperAdapter：

public class PaperAdapter extends BaseAdapter implements OnClickListener { 

private Context context; 
private List<Paper> papers; 
private LayoutInflater inflater; 
CheckBox cb; 
TextView paper; 
SqlHandler sqlHandler; 

public PaperAdapter(Context context, List<Paper> papers) { 
    this.context = context; 
    this.papers = papers; 
    inflater = LayoutInflater.from(context); 
} 

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

@Override 
public Object getItem(int position) { 
    return papers.get(position); 
} 

@Override 
public long getItemId(int position) { 
    return position; 
} 

private class ViewHolder { 
    TextView title; 
    TextView author; 
    CheckBox name; 
} 

@Override 
public View getView(int position, View view, ViewGroup viewGroup) { 

    ViewHolder holder = null; 

    // We only create the view if its needed 
    if (view == null) { 
     view = inflater.inflate(R.layout.child_row, null); 

     // Set the click listener for the checkbox 
     //view.findViewById(R.id.check1).setOnClickListener(this); 


     Paper p = (Paper) getItem(position); 

     // Set the example text and the state of the checkbox 
     CheckBox cb = (CheckBox) view.findViewById(R.id.check1); 
     //cb.setChecked(p.isSelected()); 
     // We tag the data object to retrieve it on the click listener. 

     paper = (TextView)view.findViewById(R.id.papername); 
     if (paper != null) 
      paper.setText(p.getTitle()); 

     TextView author = (TextView)view.findViewById(R.id.authorname); 
     if(author!= null) 
      author.setText(p.getAuthor()); 

     holder = new ViewHolder(); 
     holder.name = (CheckBox) view.findViewById(R.id.check1); 
     holder.title = (TextView) view.findViewById(R.id.papername); 
     holder.author= (TextView) view.findViewById(R.id.authorname); 
     view.setTag(holder); 

     holder.name.setOnClickListener(new View.OnClickListener() { 

      @Override 
      public void onClick(View v) { 
       // TODO Auto-generated method stub 
       CheckBox cb = (CheckBox) v; 
       Paper paper = (Paper) cb.getTag(); 
       String title = paper.getTitle(); 
       String author = paper.getAuthor(); 
       if (cb.isChecked()){ 
        Toast.makeText(context, "Papier "+title+ " ajouté", Toast.LENGTH_SHORT).show(); 
        //String query = "INSERT INTO SELECTED_PAPERS(title,author) values ('" 
          //+ title +"','" + author +"')"; 
        //sqlHandler.executeQuery(query); 

       } 
       if (cb.isChecked()==false){ 
        Toast.makeText(context, "Papier "+title+ " retiré", Toast.LENGTH_SHORT).show(); 
       } 
      } 
     }); 
    } 
    else{ 
     holder = (ViewHolder) view.getTag(); 
    } 

    Paper paper = papers.get(position); 
    holder.author.setText(paper.getAuthor()); 
    holder.title.setText(paper.getTitle()); 
    holder.name.setTag(paper); 

    return view; 
} 

/*@Override 
/** Will be called when a checkbox has been clicked. */ 
public void onClick(View view, int position) { 
    /*TextView p = (TextView) view.findViewById(R.id.papername); 
    TextView a = (TextView) view.findViewById(R.id.authorname); 
    CheckBox cb = (CheckBox) view.findViewById(R.id.check1); 
    String title = p.getText().toString(); 
    String author = a.getText().toString(); 
    String query = "INSERT INTO SELECTED_PAPERS(title,author) values ('" 
      + title +"','" + author +"')"; 
    sqlHandler.executeQuery(query);*/ 
    //TextView p = (TextView) view.findViewById(R.id.papername); 
    //TextView a = (TextView) view.findViewById(R.id.authorname); 
    //String title = p.getText().toString(); 
    //String author = a.getText().toString(); 
    Paper p = (Paper) this.getItem(position); 
    String title = p.getTitle(); 
    Toast.makeText(context, "Papier ajouté", Toast.LENGTH_SHORT).show(); 

} 

@Override 
public void onClick(View arg0) { 
    // TODO Auto-generated method stub 

} 

/* 
private void savePrefs(String key, String checked) { 
    SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(context); 
    Editor edit = sp.edit(); 
    edit.putString (key, checked); 
    edit.commit(); 

}*/ 


} 

非常感謝！

Answer 1

我很忙，但我會給你一些提示，幫助你向前邁進。

1. 我不碰你的適配器，使其更簡單，但考慮統一儘可能多的，你可以，如果兩個名單幾乎相同，但不同的getView()方法，使用共同的抽象基類兩個適配器並實現每個不同的getView（）。這只是一個例子。

2. 請注意您通過的上下文。不要將活動傳遞給適配器。在這種特殊情況下，似乎沒有任何傷害，但片段由FragmentManager處理，並且適配器駐留在片段中，因此您可能會將內存泄漏一段時間，直到片段被破壞。而是通過getActivity（）。getApplicationContext（）; （或者更好的是，在你的適配器的構造函數中做：this.context = context.getApplicationContext();（這種方式你總是參考）

3. 把代碼放在這裏真的很長（而且我必須回去工作！這種方式：

   • 將您的活動託管兩個（或更多）片段
   • 在你的片段（S）你執行修改相同的數據作爲另一個片段
   • 您需要通知的動作。大家誰有興趣，數據已被改變如此他們可以做任何需要的事情（更新UI，重新加載等）。

我將如何做到這一點

1. 有一個包含已經被解析talks.xml列表中選擇一個 「DataController類」 級。任何人都可以這樣做：DataController.getInstance(context).getListOfTalks();
2. DataController將檢查列表是否爲空並繼續創建/解析然後返回值。如果列表不爲空，那麼它將返回它。現在你的數據消費者不知道它來自哪裏，它總是來自同一個地方。
3. 讓適配器從DataController中獲取數據，如＃2所述。
4. 既然數據位於中央存儲庫中，請讓數據控制器實施修改/保留數據的方法（即，如果您使用代碼應該在該控制器中的SQL）。
5. 讓DataController實現一個Listener/Observer模式或類似的感興趣的團體可以訂閱並得到通知。
6. 當fragment/onclick需要檢查一個盒子時，它會告訴DataController，DataController會保存這些新數據，然後繼續向其偵聽器發出通知。
7. 每個片段在啓動時都會訂閱DataController（例如，在onStop（）中刪除它自己）。
8. 當片段收到此「通知」時，它們繼續告訴適配器更新數據。

聽起來很多，但你會獲得很多好東西。從視圖中分離數據，統一的地方，建立一個共同的通信模式等

這個DataController類的一些僞代碼將是...

public class DataController { 
    private static DataController sDataController; 
    private final Context mAppContext; 
    private final List<DataChangeListener> mListeners = new ArrayList<DataChangeListener>(); 
    private List<Talks> mData; 
    private DataController(final Context appContext) { 
     mAppContext = appContext; 
    } 
    public static DataController get(Context context) { 
     if (sDataController == null) { 
      if (context != null) { 
       sDataController = new DataController(context.getApplicationContext()); 
      } else { 
       sDataController = new DataController(YourAppClass.getInstance().getApplicationContext()); 
      } 
     } 
     return sDataController; 
    } 
    /** 
    * {@link DataChangeListener} listeners will be notified when certain requests have been made. 
    * 
    * @param listener - a valid DataChangeListener. If null, nothing is added. 
    */ 
    public void addDataChangeListener(DataChangeListener listener) { 
     if (listener != null && !mListeners.contains(listener)) { 
      mListeners.add(listener); 
     } 
    } 
    /** 
    * Remove a {@link DataChangeListener} from the list. 
    * 
    * @param listener - a valid DataChangeListener. If null, nothing is removed. 
    */ 
    public void addDataChangeListener(DataChangeListener listener) { 
     if (listener != null) { 
      mListeners.remove(listener); 
     } 
    } 

// INTERESTING METHODS YOU HAVE TO IMPLEMENT 

    public List<Talks> getData(){ 
     if (mData == null) { 
      parseData();// implement this 
     } 
     return mData; 
    } 
    public void checkBoxChanged(final somedatatype somedata) { 
     // pass the appropriate values you need and save them to your sql, update the list of talks 
     // talks should contain the value of the checkbox, add it to your Talks object if it's not there. 
     updateSQL(); 
     notifyDataChnged(); 
    } 
    public notifyDataChnged(){ 
     if (mListeners != null) { 
      for (DataChangeListener listener : mListeners) { 
       listener.onDataSetChanged(); 
      } 
     } 
    } 
} 

這是接口：

public interface DataChangeListener { 
    void onDataSetChanged(); 
} 

現在你的碎片會做類似的事情：

@Override 
    public void onResume() { 
     super.onResume(); 
     DataController.getInstance(context).addDataChangeListener(this); 
    } 
    @Override 
    public void onPause() { 
     super.onPause(); 
     DataController.getInstance(context).removeDataChangeListener(this); 
    } 

當然，他們實現接口...

public class PapersFragment extends Fragment implements DataChangeListener { 

和有義務方法...

@Override 
public void onDataSetChanged(){ 
// Data has changed, do something about it, like telling the adapter and doing anything you see fit. 
} 

我覺得這是一個很好的起點，這將導致你更好的建築設計。

祝你好運！