程序在列表视图中的ViewHolder上崩溃

时间：2012-09-25 22:10:14

标签： android android-layout android-listview

我在下面粘贴了我的代码，概念是我有3种不同类型的listview项目，可以通过viewholder类看到。现在当我滚动列表视图时，它会在freeTextHolder = (ViewHolderFreeText) rowView.getTag();上崩溃，因为_position与所需的itemList对象不匹配，该位置会显示其"free text"所以if (itemList.get(_position).getType().compareTo(Question.TYPE_CATEGORY) == 0)获得了真，但rowView.getTag()显示了一个复选框，因此_position 1增加了所需的位置，然后崩溃了。

    @Override
public View getView(final int _position, View _convertView,
        ViewGroup _parent) {

    View rowView = _convertView;
    if (itemList.get(_position).getType().compareTo(Question.TYPE_CATEGORY) == 0) {
        ViewHolderBranch branchHolder = new ViewHolderBranch();

        // Compartment for Branch
        if (rowView == null) {
            LayoutInflater inflater = (LayoutInflater) context
                    .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            rowView = inflater.inflate(R.layout.listview_branch, _parent,
                    false);

            branchHolder.hTextTitle = (TextView) rowView
                    .findViewById(R.id.textTitleB);
            branchHolder.hTextDetail = (TextView) rowView
                    .findViewById(R.id.textDetailB);
            branchHolder.hIcon = (ImageView) rowView
                    .findViewById(R.id.imageArrow);

            rowView.setTag(branchHolder);
        } else {

            branchHolder = (ViewHolderBranch) rowView.getTag();
        }

        branchHolder.hTextTitle.setText(itemList.get(_position).getText());
        if (itemList.get(_position).isIsReadCode())
            branchHolder.hTextDetail.setText(itemList.get(_position)
                    .getReadCode());
        else
            branchHolder.hTextDetail.setText(" ");
        branchHolder.hIcon
                .setImageResource(android.R.drawable.ic_media_play);

        // return rowView;
    }

    else if (itemList.get(_position).getType()
            .compareTo(Question.TYPE_CHECKBOX) == 0) {
        // Compartment for Checkboxes

        ViewHolderCheckbox checkboxHolder = new ViewHolderCheckbox();

        // Compartment for Branch
        if (rowView == null) {
            LayoutInflater inflater = (LayoutInflater) context
                    .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            rowView = inflater.inflate(R.layout.listview_checkbox, _parent,
                    false);

            checkboxHolder.hTextTitle = (TextView) rowView
                    .findViewById(R.id.textTitleCB);
            checkboxHolder.hTextDetail = (TextView) rowView
                    .findViewById(R.id.textDetailCB);
            checkboxHolder.hCheckBox = (CheckBox) rowView
                    .findViewById(R.id.checkBox);
            rowView.setTag(checkboxHolder);
        } else {

            checkboxHolder = (ViewHolderCheckbox) rowView.getTag();
        }

        checkboxHolder.hTextTitle
                .setText(itemList.get(_position).getText());
        if (itemList.get(_position).isIsReadCode())
            checkboxHolder.hTextDetail.setText(itemList.get(_position)
                    .getReadCode());
        else
            checkboxHolder.hTextDetail.setText(" ");
        checkboxHolder.hCheckBox.setChecked(itemList.get(_position)
                .isChecked());

        // return rowView;

    }

    if (itemList.get(_position).getType().compareTo(Question.TYPE_FREETEXT) == 0) {
        ViewHolderFreeText freeTextHolder = new ViewHolderFreeText();

        // Compartment for Branch
        if (rowView == null) {
            LayoutInflater inflater = (LayoutInflater) context
                    .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            rowView = inflater.inflate(R.layout.listview_button, _parent,
                    false);

            freeTextHolder.hTextTitle = (TextView) rowView
                    .findViewById(R.id.textTitleBtn);
            freeTextHolder.hTextDetail = (TextView) rowView
                    .findViewById(R.id.textDetailBtn);
            freeTextHolder.hIcon = (ImageView) rowView
                    .findViewById(R.id.imagePlusBtn);

            rowView.setTag(freeTextHolder);
        } else {

            freeTextHolder = (ViewHolderFreeText) rowView.getTag();
        }

        freeTextHolder.hTextTitle.setText(itemList.get(_position).getText());
        if (itemList.get(_position).isIsReadCode())
            freeTextHolder.hTextDetail.setText(itemList.get(_position)
                    .getReadCode());
        else
            freeTextHolder.hTextDetail.setText(" ");
        freeTextHolder.hIcon
                .setImageResource(android.R.drawable.ic_input_add);

        // return rowView;
    }

    return rowView;
}

@Override
public int getCount() {
    // TODO Auto-generated method stub
    return itemList.size();
}

@Override
public Object getItem(int _position) {
    // TODO Auto-generated method stub
    return _position;
}

@Override
public long getItemId(int _position) {
    // TODO Auto-generated method stub
    return _position;
}

和视图持有人类

静态类ViewHolderBranch {         TextView hTextTitle;         TextView hTextDetail;         ImageView hIcon;     } 

static class ViewHolderFreeText
{
    TextView hTextTitle;
    TextView hTextDetail;
    ImageView hIcon;
}

// View Holder for Checkbox Items
/**
 * Class for holding different view items
 * 
 */
static class ViewHolderCheckbox {
    TextView hTextTitle;
    TextView hTextDetail;
    CheckBox hCheckBox;
}

微量

  09-23 15:36:29.105: D/AndroidRuntime(8908): Shutting down VM 09-23 15:36:29.105: W/dalvikvm(8908): threadid=1: thread exiting with
 uncaught exception (group=0x40014760) 09-23 15:36:29.326:
 E/AndroidRuntime(8908): FATAL EXCEPTION: main 09-23 15:36:29.326:
 E/AndroidRuntime(8908): java.lang.ClassCastException:
 com.techmelo.ws.CustomizeLViewAdapter$ViewHolderBranch cannot be cast
 to com.techmelo.ws.CustomizeLViewAdapter$ViewHolderFreeText 09-23
 15:36:29.326: E/AndroidRuntime(8908):  at
 com.techmelo.ws.CustomizeLViewAdapter.getView(CustomizeLViewAdapter.java:157)
 09-23 15:36:29.326: E/AndroidRuntime(8908):    at
 android.widget.AbsListView.obtainView(AbsListView.java:1943) 09-23
 15:36:29.326: E/AndroidRuntime(8908):  at
 android.widget.ListView.makeAndAddView(ListView.java:1756) 09-23
 15:36:29.326: E/AndroidRuntime(8908):  at
 android.widget.ListView.fillDown(ListView.java:656) 09-23
 15:36:29.326: E/AndroidRuntime(8908):  at
 android.widget.ListView.fillGap(ListView.java:620) 09-23 15:36:29.326:
 E/AndroidRuntime(8908):    at
 android.widget.AbsListView.trackMotionScroll(AbsListView.java:4350)
 09-23 15:36:29.326: E/AndroidRuntime(8908):    at
 android.widget.AbsListView.onTouchEvent(AbsListView.java:2892) 09-23
 15:36:29.326: E/AndroidRuntime(8908):  at
 android.widget.ListView.onTouchEvent(ListView.java:3566) 09-23
 15:36:29.326: E/AndroidRuntime(8908):  at
 android.view.View.dispatchTouchEvent(View.java:4600) 09-23
 15:36:29.326: E/AndroidRuntime(8908):  at
 android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1488)
 09-23 15:36:29.326: E/AndroidRuntime(8908):    at
 android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1256) 09-23
 15:36:29.326: E/AndroidRuntime(8908):  at
 android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1494)
 09-23 15:36:29.326: E/AndroidRuntime(8908):    at
 android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1269) 09-23
 15:36:29.326: E/AndroidRuntime(8908):  at
 android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1494)
 09-23 15:36:29.326: E/AndroidRuntime(8908):    at
 android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1269) 09-23
 15:36:29.326: E/AndroidRuntime(8908):  at
 android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1494)
 09-23 15:36:29.326: E/AndroidRuntime(8908):    at
 android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1269) 09-23
 15:36:29.326: E/AndroidRuntime(8908):  at
 android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1494)
 09-23 15:36:29.326: E/AndroidRuntime(8908):    at
 android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1269) 09-23
 15:36:29.326: E/AndroidRuntime(8908):  at
 android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1494)
 09-23 15:36:29.326: E/AndroidRuntime(8908):    at
 android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1269) 09-23
 15:36:29.326: E/AndroidRuntime(8908):  at
 android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1494)
 09-23 15:36:29.326: E/AndroidRuntime(8908):    at
 android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1269) 09-23
 15:36:29.326: E/AndroidRuntime(8908):  at
 android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1494)
 09-23 15:36:29.326: E/AndroidRuntime(8908):    at
 android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1269) 09-23
 15:36:29.326: E/AndroidRuntime(8908):  at
 com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1700)
 09-23 15:36:29.326: E/AndroidRuntime(8908):    at
 com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1270)
 09-23 15:36:29.326: E/AndroidRuntime(8908):    at
 android.app.Activity.dispatchTouchEvent(Activity.java:2277) 09-23
 15:36:29.326: E/AndroidRuntime(8908):  at
 com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1680)
 09-23 15:36:29.326: E/AndroidRuntime(8908):    at
 android.view.ViewRoot.deliverPointerEvent(ViewRoot.java:2272) 09-23
 15:36:29.326: E/AndroidRuntime(8908):  at
 android.view.ViewRoot.handleMessage(ViewRoot.java:1958) 09-23
 15:36:29.326: E/AndroidRuntime(8908):  at
 android.os.Handler.dispatchMessage(Handler.java:99) 09-23
 15:36:29.326: E/AndroidRuntime(8908):  at
 android.os.Looper.loop(Looper.java:126) 09-23 15:36:29.326:
 E/AndroidRuntime(8908):    at
 android.app.ActivityThread.main(ActivityThread.java:3997) 09-23
 15:36:29.326: E/AndroidRuntime(8908):  at
 java.lang.reflect.Method.invokeNative(Native Method) 09-23
 15:36:29.326: E/AndroidRuntime(8908):  at
 java.lang.reflect.Method.invoke(Method.java:491) 09-23 15:36:29.326:
 E/AndroidRuntime(8908):    at
 com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
 09-23 15:36:29.326: E/AndroidRuntime(8908):    at
 com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599) 09-23
 15:36:29.326: E/AndroidRuntime(8908):  at
 dalvik.system.NativeStart.main(Native Method) 09-23 15:36:39.334:
 W/ActivityThread(9001): Application com.techmelo.ws is waiting for the
 debugger on port 8100... 09-23 15:36:39.345: I/System.out(9001):
 Sending WAIT chunk 09-23 15:36:39.364: I/dalvikvm(9001): Debugger is
 active 09-23 15:36:39.554: I/System.out(9001): Debugger has connected
 09-23 15:36:39.554: I/System.out(9001): waiting for debugger to
 settle... 09-23 15:36:39.808: I/System.out(9001): waiting for debugger
 to settle... 09-23 15:36:40.014: I/System.out(9001): waiting for
 debugger to settle... 09-23 15:36:40.216: I/System.out(9001): waiting
 for debugger to settle... 09-23 15:36:40.416: I/System.out(9001):
 waiting for debugger to settle... 09-23 15:36:40.647:
 I/System.out(9001): waiting for debugger to settle... 09-23
 15:36:40.884: I/System.out(9001): waiting for debugger to settle...
 09-23 15:36:41.085: I/System.out(9001): waiting for debugger to
 settle... 09-23 15:36:41.299: I/System.out(9001): waiting for debugger
 to settle... 09-23 15:36:41.524: I/System.out(9001): waiting for
 debugger to settle... 09-23 15:36:41.755: I/System.out(9001): debugger
 has settled (1390) 09-23 15:36:42.994: D/dalvikvm(9001): GC_FOR_ALLOC
 freed 63K, 4% free 6386K/6599K, paused 45ms 09-23 15:36:43.004:
 I/dalvikvm-heap(9001): Grow heap (frag case) to 6.820MB for
 513744-byte allocation 09-23 15:36:43.284: D/dalvikvm(9001):
 GC_CONCURRENT freed <1K, 4% free 6888K/7111K, paused 29ms+2ms 09-23
 15:36:46.084: V/TLINE(9001): new: android.text.TextLine@40719db0 09-23
 15:36:47.904: V/TLINE(9001): new: android.text.TextLine@4072b720 09-23
 15:37:11.404: D/dalvikvm(9001): threadid=1: still suspended after undo
 (sc=1 dc=1) 09-23 15:37:11.414: D/dalvikvm(9001): GC_CONCURRENT freed
 117K, 4% free 7263K/7495K, paused 13ms+8ms

1 个答案:

答案 0 :(得分：2)

发生异常是因为您的不同代码分支（对于不同类型的行）可能都处理重用的行视图，该视图具有与之关联的任何类型的标记对象。

最佳解决方案是覆盖Adapter的{​​{1}}和getItemViewType(int)方法，以指定您拥有多少种不同类型的项目视图，并将这些视图映射到列表位置。这将简化getViewTypeCount()中的逻辑，让getView(...)以不同的视图类型处理行回收池。

您可以将ListView中的测试更改为：

getView(...)

其中if (getItemViewType(_position) == TYPE_CATEGORY) { // code for categories } 是您的Adapter子类知道的TYPE_CATEGORY。

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