Casella di controllo in ExpandableListView

Question

Sto utilizzando un in cui ogni gruppo è un TextView e ogni bambino è un CheckBox. Stavo cercando di implementare qualcosa di simile a questo link:

http://www.vogella.de/articles/AndroidListView/article.html#listadvanced_interactive

ma con un ExpandableListView invece di ListView. In fase di esecuzione, viene fornito uno strano ClassCastException mentre si imposta Tag per la casella di controllo utilizzando setTag(). Ecco il codice:

public class ExpandableActivity extends Activity { 

@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.main); 

    ArrayList<String> groups = new ArrayList<String>(); 
    List<List<OptionItem>> children = new ArrayList<List<OptionItem>>(); 

    for (int i = 0; i < 10; i++) { 
     String groupName = "Group " + i; 
     groups.add(groupName); 
     List<OptionItem> temp = new ArrayList<OptionItem>(); 
     for (int j = 0; j < 5; j++) { 
      temp.add(new OptionItem(groupName, "Child " + j)); 
     } 
     children.add(temp); 
    } 

    children.get(0).get(3).setSelected(true); 
    children.get(5).get(2).setSelected(true); 
    children.get(8).get(1).setSelected(true); 
    children.get(3).get(4).setSelected(true); 

    ExpandableListView elv = (ExpandableListView) findViewById(R.id.expandableListView1); 
    elv.setAdapter(new ExpandableAdapter(groups, children)); 

} 

public static class ViewHolder { 
    protected CheckBox cb; 
} 

public class ExpandableAdapter extends BaseExpandableListAdapter { 

    private List<List<OptionItem>> list; 
    private ArrayList<String> groups; 

    public ExpandableAdapter(ArrayList<String> groups, 
      List<List<OptionItem>> children) { 
     this.groups = groups; 
     this.list = children; 
    } 

    @Override 
    public Object getChild(int groupPosition, int childPosition) { 
     if (list != null && list.size() > groupPosition 
       && list.get(groupPosition) != null) { 
      if (list.get(groupPosition).size() > childPosition) 
       return list.get(groupPosition).get(childPosition); 
     } 

     return null; 
    } 

    @Override 
    public long getChildId(int groupPosition, int childPosition) { 
     return childPosition; 
    } 

    @Override 
    public View getChildView(final int groupPosition, 
      final int childPosition, boolean isLastChild, View convertView, 
      ViewGroup parent) { 

     View view = null; 
     if (convertView == null) { 
      view = getLayoutInflater().inflate(R.layout.row, null); 
      final ViewHolder childHolder = new ViewHolder(); 
      childHolder.cb = (CheckBox) view.findViewById(R.id.checkBox1);    
      childHolder.cb 
        .setOnCheckedChangeListener(new OnCheckedChangeListener() { 
         @Override 
         public void onCheckedChanged(CompoundButton button, 
           boolean isChecked) { 
          OptionItem item = (OptionItem) childHolder.cb 
            .getTag(); 
          item.setSelected(button.isChecked()); 
         } 
        }); 

      view.setTag(childHolder); 
      childHolder.cb.setTag(list.get(groupPosition).get(childPosition)); 
     } else { 
      view = convertView;   
      ((ViewHolder) view.getTag()).cb.setTag(list.get(groupPosition).get(childPosition)); 
     } 

     ViewHolder holder = (ViewHolder) view.getTag(); 
     holder.cb.setChecked(list.get(groupPosition).get(childPosition) 
       .isSelected()); 
     holder.cb.setText(list.get(groupPosition).get(childPosition) 
       .getChildName()); 

     return view; 
    } 

    @Override 
    public int getChildrenCount(int groupPosition) { 
     if (list != null && list.size() > groupPosition 
       && list.get(groupPosition) != null) 
      return list.get(groupPosition).size(); 

     return 0; 
    } 

    @Override 
    public Object getGroup(int groupPosition) { 
     if (groups != null && groups.size() > groupPosition) 
      return groups.get(groupPosition); 

     return null; 
    } 

    @Override 
    public int getGroupCount() { 
     if (groups != null) 
      return groups.size(); 

     return 0; 
    } 

    @Override 
    public long getGroupId(int groupPosition) { 
     return groupPosition; 
    } 

    @Override 
    public View getGroupView(int groupPosition, boolean isExpanded, 
      View convertView, ViewGroup parent) { 
     if (convertView == null) { 
      convertView = getLayoutInflater().inflate(
        android.R.layout.simple_expandable_list_item_1, null); 
     } 

     TextView tv = (TextView) convertView 
       .findViewById(android.R.id.text1); 
     tv.setText(groups.get(groupPosition)); 

     return convertView; 
    } 

    @Override 
    public boolean hasStableIds() { 
     return true; 
    } 

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

e la classe modello di dati:

public class OptionItem { 

private String groupName; 
private String childName; 
private boolean selected; 

public OptionItem(String group, String child) { 

    this.groupName = group; 
    this.childName = child; 
    selected = false; 
} 

public void setGroupName(String name) { 
    this.groupName = name; 
} 

public void setChildName(String name) { 
    this.childName = name; 
} 

public void setSelected(boolean selected) { 
    this.selected = selected; 
} 

public String getGroupName() { 
    return groupName; 
} 

public String getChildName() { 
    return childName; 
} 

public boolean isSelected() { 
    return selected; 
} 

prega di aiuto. Grazie in anticipo.

EDIT: Il registro è la seguente:

02-15 12:40:03.224: E/AndroidRuntime(423): FATAL EXCEPTION: main 
02-15 12:40:03.224: E/AndroidRuntime(423): java.lang.ClassCastException: com.test.OptionItem 
02-15 12:40:03.224: E/AndroidRuntime(423): at com.test.ExpandableActivity$ExpandableAdapter.getChildView(ExpandableActivity.java:106) 
02-15 12:40:03.224: E/AndroidRuntime(423): at android.widget.ExpandableListConnector.getView(ExpandableListConnector.java:450) 
02-15 12:40:03.224: E/AndroidRuntime(423): at android.widget.AbsListView.obtainView(AbsListView.java:1315) 
02-15 12:40:03.224: E/AndroidRuntime(423): at android.widget.ListView.makeAndAddView(ListView.java:1727) 
02-15 12:40:03.224: E/AndroidRuntime(423): at android.widget.ListView.fillDown(ListView.java:652) 
02-15 12:40:03.224: E/AndroidRuntime(423): at android.widget.ListView.fillSpecific(ListView.java:1284) 
02-15 12:40:03.224: E/AndroidRuntime(423): at android.widget.ListView.layoutChildren(ListView.java:1558) 
02-15 12:40:03.224: E/AndroidRuntime(423): at android.widget.AbsListView.onLayout(AbsListView.java:1147) 
02-15 12:40:03.224: E/AndroidRuntime(423): at android.view.View.layout(View.java:7035) 
02-15 12:40:03.224: E/AndroidRuntime(423): at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1249) 
02-15 12:40:03.224: E/AndroidRuntime(423): at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1125) 
02-15 12:40:03.224: E/AndroidRuntime(423): at android.widget.LinearLayout.onLayout(LinearLayout.java:1042) 
02-15 12:40:03.224: E/AndroidRuntime(423): at android.view.View.layout(View.java:7035) 
02-15 12:40:03.224: E/AndroidRuntime(423): at android.widget.FrameLayout.onLayout(FrameLayout.java:333) 
02-15 12:40:03.224: E/AndroidRuntime(423): at android.view.View.layout(View.java:7035) 
02-15 12:40:03.224: E/AndroidRuntime(423): at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1249) 
02-15 12:40:03.224: E/AndroidRuntime(423): at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1125) 
02-15 12:40:03.224: E/AndroidRuntime(423): at android.widget.LinearLayout.onLayout(LinearLayout.java:1042) 
02-15 12:40:03.224: E/AndroidRuntime(423): at android.view.View.layout(View.java:7035) 
02-15 12:40:03.224: E/AndroidRuntime(423): at android.widget.FrameLayout.onLayout(FrameLayout.java:333) 
02-15 12:40:03.224: E/AndroidRuntime(423): at android.view.View.layout(View.java:7035) 
02-15 12:40:03.224: E/AndroidRuntime(423): at android.view.ViewRoot.performTraversals(ViewRoot.java:1045) 
02-15 12:40:03.224: E/AndroidRuntime(423): at android.view.ViewRoot.handleMessage(ViewRoot.java:1727) 
02-15 12:40:03.224: E/AndroidRuntime(423): at android.os.Handler.dispatchMessage(Handler.java:99) 
02-15 12:40:03.224: E/AndroidRuntime(423): at android.os.Looper.loop(Looper.java:123) 
02-15 12:40:03.224: E/AndroidRuntime(423): at android.app.ActivityThread.main(ActivityThread.java:4627) 
02-15 12:40:03.224: E/AndroidRuntime(423): at java.lang.reflect.Method.invokeNative(Native Method) 
02-15 12:40:03.224: E/AndroidRuntime(423): at java.lang.reflect.Method.invoke(Method.java:521) 
02-15 12:40:03.224: E/AndroidRuntime(423): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) 
02-15 12:40:03.224: E/AndroidRuntime(423): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) 
02-15 12:40:03.224: E/AndroidRuntime(423): at dalvik.system.NativeStart.main(Native Method) 

EDIT: ho provato di nuovo, è ancora dando la stessa eccezione. Qui ci sono le importazioni ho aggiunto:

import java.util.ArrayList; 
import java.util.List; 
import android.app.Activity; 
import android.os.Bundle; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.BaseExpandableListAdapter; 
import android.widget.CheckBox; 
import android.widget.CompoundButton; 
import android.widget.CompoundButton.OnCheckedChangeListener; 
import android.widget.ExpandableListView; 
import android.widget.TextView; 

Answer 1

Grazie a Natali, ho capito il problema. Il problema era nel file di layout "row.xml". Stavo usando:

<?xml version="1.0" encoding="utf-8"?> 
<CheckBox xmlns:android="http://schemas.android.com/apk/res/android" 
    android:id="@+id/checkBox1" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:text="CheckBox" /> 

come il layout. Ma quando ho cambiato in:

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent" 
    android:orientation="vertical" > 

    <CheckBox 
     android:id="@+id/checkBox1" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:text="CheckBox" /> 

</LinearLayout> 

Ha funzionato come un fascino. Immagino che questo sia un bug. Grazie a Natali per avermi aiutato a capirlo.

Answer 2

cerco il tuo codice, e non ci sono problemi:

invitiamo ad aggiungere le importazioni, forse ci sono alcuni problemi.