android.widget.listview 无法转换为 android.widget.expandablelistview

android.widget.listview cannot be cast to android.widget.expandablelistview

在我的 android 应用程序中,我将适配器从 ListViewAdapter 更改为 ExpendableListViewAdapter。在此之前,ListViewAdapter 仅一个接一个地加载产品。但是现在我想把这些产品分成几组。

这就是我在 ProductActivity.java 中的 ExpendableListViewAdapter:

class ExpandableListAdapter extends BaseExpandableListAdapter {

    private Context _context;
    private List<String> _listDataHeader; // header titles
    // child data in format of header title, child title
    private Map<String, List<Product>> _listDataChild;
    private boolean viewOnly;
    private Config config;

    public ExpandableListAdapter(Context context, List<String> listDataHeader,
            Map<String, List<Product>> listChildData, boolean viewOnly, Config config) {
        this._context = context;
        this._listDataHeader = listDataHeader;
        this._listDataChild = listChildData;
        this.viewOnly = viewOnly;
        this.config = config;
    }

    @Override
    public Object getChild(int groupPosition, int childPosititon) {
        return this._listDataChild.get(this._listDataHeader.get(groupPosition))
                .get(childPosititon);
    }

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

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

        final String childText = (String) getChild(groupPosition, childPosition);
        Product product = (Product) getChild(groupPosition, childPosition);

        if (convertView == null) {
            LayoutInflater infalInflater = (LayoutInflater) this._context
                    .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            convertView = infalInflater.inflate(R.layout.product_item, null);

            CheckBox name = (CheckBox) convertView.findViewById(R.id.product_item_checkbox);
            TextView price_value = (TextView) convertView.findViewById(R.id.product_item_price_value);
            TextView price_value_vo = (TextView) convertView.findViewById(R.id.product_item_price_value_vo);
            TextView price_textview = (TextView) convertView.findViewById(R.id.product_item_price_textview);
            DatePicker from = (DatePicker) convertView.findViewById(R.id.product_item_datePicker_from);
            EditText serial_number = (EditText) convertView.findViewById(R.id.product_item_edittext);
            serial_number.addTextChangedListener(new GenericTextWatcherCustom(product));
            TextView item_lenght = (TextView) convertView.findViewById(R.id.product_item_lenght);
            TextView item_lenght_vo = (TextView) convertView.findViewById(R.id.product_item_lenght_vo);
            TextView item_type = (TextView) convertView.findViewById(R.id.product_item_type); 
            TextView item_type_vo = (TextView) convertView.findViewById(R.id.product_item_type_vo);
            TextView name_only = (TextView) convertView.findViewById(R.id.product_item_name);

            name.setOnClickListener( new View.OnClickListener() { 
                public void onClick(View v) { 
                    CheckBox cb = (CheckBox) v ; 
                    Product product = (Product) cb.getTag(); 
                    product.setSelected(cb.isChecked());
                } 
            }); 


            DatePicker.OnDateChangedListener mDateListenerFrom = new DatePicker.OnDateChangedListener() {

                @Override
                public void onDateChanged(DatePicker view, int year, int monthOfYear, int dayOfMonth) {
                    Product product = (Product) view.getTag(); 
                    @SuppressWarnings("deprecation")
                    Date date = new Date(year - 1900,monthOfYear,dayOfMonth);
                    product.setFrom(date);
                }
            };

            Calendar cal = product.getActive_toDate();
            if (cal == null){
               cal = Calendar.getInstance();
            }
            Date date = new Date(cal.get(Calendar.YEAR) - 1900,cal.get(Calendar.MONTH),cal.get(Calendar.DAY_OF_MONTH));
            from.setMinDate(date.getTime());
            from.init(cal.get(Calendar.YEAR),cal.get(Calendar.MONTH), cal.get(Calendar.DAY_OF_MONTH), mDateListenerFrom);
            product.setFrom(date);


           //quantity.setTag(product);  
           name.setTag(product);
           from.setTag(product);
           name.setChecked(product.getSelected());
           name.setText(product.getName());
           name_only.setText(product.getName());
           name_only.setVisibility(8);
           item_lenght_vo.setVisibility(8);
           item_type_vo.setVisibility(8);
           price_value.setText(product.getPrice());
           price_value_vo.setText(product.getPrice());
           price_value_vo.setVisibility(8);            

           if (product.getUnit().compareTo("hardware") == 0){
               from.setVisibility(DatePicker.INVISIBLE);
               serial_number.setVisibility(EditText.VISIBLE);
               serial_number.setText(product.getSerial_number());
               item_lenght_vo.setText(product.getUnit());
               item_lenght.setText(product.getUnit());
               item_type.setText("Serial number");
           }else{
               serial_number.setVisibility(DatePicker.INVISIBLE);
               from.setVisibility(EditText.VISIBLE);
               if (config.getConfig_change_sales_date().compareTo("0") == 0){
                   from.setEnabled(false);
               }
               item_lenght.setText(product.getUnit_length() + " " + product.getUnit());
               item_lenght_vo.setText(product.getUnit_length() + " " + product.getUnit());
               item_type.setText("Product start");
           }

           if (viewOnly){   
               name_only.setVisibility(0);
               name.setVisibility(8);
               from.setVisibility(8);                
               serial_number.setVisibility(8);
               item_type_vo.setVisibility(0);
               item_type.setVisibility(8);
               item_lenght.setVisibility(8);
               item_lenght_vo.setVisibility(0);
               item_lenght_vo.setTextColor(Color.LTGRAY);
               price_value.setVisibility(8);
               price_value_vo.setVisibility(0);
               price_value_vo.setTextColor(Color.LTGRAY);
               price_textview.setVisibility(8); 
               historyButton.setVisibility(8);

               // Height adjustment of product box
               convertView.setLayoutParams(new ListView.LayoutParams(ListView.LayoutParams.MATCH_PARENT, ListView.LayoutParams.WRAP_CONTENT));  


               // backButton to the whole width
               backButton.setLayoutParams(new LinearLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT, 1.0f));


               //  Set the same width
               Display display = getWindowManager().getDefaultDisplay(); 
               @SuppressWarnings("deprecation")
               int width = display.getWidth();

               name_only.measure(MeasureSpec.UNSPECIFIED,MeasureSpec.UNSPECIFIED);
               item_lenght_vo.measure(MeasureSpec.UNSPECIFIED,MeasureSpec.UNSPECIFIED);


               if(name_only.getMeasuredWidth() < item_lenght_vo.getMeasuredWidth()) {
                   name_only.setLayoutParams(new RelativeLayout.LayoutParams(item_lenght_vo.getMeasuredWidth(), LayoutParams.WRAP_CONTENT));
               }
               else {
                   RelativeLayout.LayoutParams rl = new RelativeLayout.LayoutParams(name_only.getMeasuredWidth(), LayoutParams.WRAP_CONTENT);
                   rl.addRule(RelativeLayout.BELOW, R.id.product_item_name);
                   rl.topMargin = 10;
                   item_lenght_vo.setLayoutParams(rl);
               };

               RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
               params.setMargins(70, 0, 0, 0);
               params.addRule(RelativeLayout.RIGHT_OF, R.id.product_item_name);
               item_type_vo.setLayoutParams(params);
               RelativeLayout.LayoutParams params2 = new RelativeLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
               params2.setMargins(70, 10, 0, 0);
               params2.addRule(RelativeLayout.BELOW, R.id.product_item_name);
               params2.addRule(RelativeLayout.RIGHT_OF, R.id.product_item_name);
               price_value_vo.setLayoutParams(params2);
           };

        }
        return convertView;
    }

    @Override
    public int getChildrenCount(int groupPosition) {
        return this._listDataChild.get(this._listDataHeader.get(groupPosition))
                .size();
    }

    @Override
    public Object getGroup(int groupPosition) {
        return this._listDataHeader.get(groupPosition);
    }

    @Override
    public int getGroupCount() {
        return this._listDataHeader.size();
    }

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

    @Override
    public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {
        String headerTitle = (String) getGroup(groupPosition);
        Product product = (Product) getGroup(groupPosition);
        if (convertView == null) {
            LayoutInflater infalInflater = (LayoutInflater) this._context
                    .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            convertView = infalInflater.inflate(R.layout.group_separator, null);
        }

        Button group_name = (Button) convertView.findViewById(R.id.product_group_name);
        group_name.setText(product.getGroup_name());

        return convertView;
    }

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

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

但是当我启动 ProductActivity.java 它抛出这个异常:

01-30 11:27:36.736: E/AndroidRuntime(1059): FATAL EXCEPTION: main
01-30 11:27:36.736: E/AndroidRuntime(1059): Process: com.example.printhelper, PID: 1059
01-30 11:27:36.736: E/AndroidRuntime(1059): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.printhelper/com.example.printhelper.ProductActivity}: java.lang.ClassCastException: android.widget.ListView cannot be cast to android.widget.ExpandableListView
01-30 11:27:36.736: E/AndroidRuntime(1059):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
01-30 11:27:36.736: E/AndroidRuntime(1059):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
01-30 11:27:36.736: E/AndroidRuntime(1059):     at android.app.ActivityThread.access0(ActivityThread.java:135)
01-30 11:27:36.736: E/AndroidRuntime(1059):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
01-30 11:27:36.736: E/AndroidRuntime(1059):     at android.os.Handler.dispatchMessage(Handler.java:102)
01-30 11:27:36.736: E/AndroidRuntime(1059):     at android.os.Looper.loop(Looper.java:136)
01-30 11:27:36.736: E/AndroidRuntime(1059):     at android.app.ActivityThread.main(ActivityThread.java:5017)
01-30 11:27:36.736: E/AndroidRuntime(1059):     at java.lang.reflect.Method.invokeNative(Native Method)
01-30 11:27:36.736: E/AndroidRuntime(1059):     at java.lang.reflect.Method.invoke(Method.java:515)
01-30 11:27:36.736: E/AndroidRuntime(1059):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
01-30 11:27:36.736: E/AndroidRuntime(1059):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
01-30 11:27:36.736: E/AndroidRuntime(1059):     at dalvik.system.NativeStart.main(Native Method)
01-30 11:27:36.736: E/AndroidRuntime(1059): Caused by: java.lang.ClassCastException: android.widget.ListView cannot be cast to android.widget.ExpandableListView
01-30 11:27:36.736: E/AndroidRuntime(1059):     at com.example.printhelper.ProductActivity.onCreate(ProductActivity.java:131)
01-30 11:27:36.736: E/AndroidRuntime(1059):     at android.app.Activity.performCreate(Activity.java:5231)
01-30 11:27:36.736: E/AndroidRuntime(1059):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
01-30 11:27:36.736: E/AndroidRuntime(1059):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
01-30 11:27:36.736: E/AndroidRuntime(1059):     ... 11 more

ProductActivity.java 中的第 131 行是这样的:

productList = (ExpandableListView)findViewById(R.id.detail_listView);

这是所有适配器变量的声明:

public class ProductActivity extends Activity {


private ExpandableListView productList;
ExpandableListAdapter dataAdapter = null;
Map<String, List<Product>> product = new HashMap<String, List<Product>>();
List<String> groups;

protected void onCreate(Bundle savedInstanceState) {
    ...
    ...
    productList = (ExpandableListView)findViewById(R.id.detail_listView);
    productList.setItemsCanFocus(true);
    createProductList();
}

public void createProductList(){
    ...
    dataAdapter = new ExpandableListAdapter(this,groups,product,viewOnly,config);
    productList.setAdapter(dataAdapter);
}

class ExpandableListAdapter extends BaseExpandableListAdapter {
    ...
    ...
}

}

真不知道怎么回事。而且也不知道适配器写的好不好...

编辑:product.xml 布局:

....
<ExpandableListView
    android:id="@+id/detail_listView"
    android:layout_width="fill_parent"
    android:layout_height="0dip"
    android:layout_weight="46"
    android:background="@color/dark_gray"
    android:choiceMode="none"
    android:drawSelectorOnTop="false"
    android:descendantFocusability="beforeDescendants"
    />
 ...

如日志:

ListView cannot be cast to android.widget.ExpandableListView

意味着 detail_listViewListView 而不是 Activity 的 xml 布局中的 ExpandableListView

在xml中使用ExpandableListView:

<ExpandableListView android:id="@+id/detail_listView"
    android:layout_width="match_parent" 
    android:layout_height="match_parent" />

无法将 ListView 转换为 ExpandableListView。您必须使用 ExpandableListView 来设置此适配器。