android - リストビューでViewHolderを使用するとプログラムがクラッシュする

Question

以下にコードを貼り付けました。概念は、ビューホルダークラスで表示できる 3 種類のリストビューアイテムを持っているということです。リストビューをスクロールすると、位置の目的のオブジェクトと一致しないためfreeTextHolder = (ViewHolderFreeText) rowView.getTag();、クラッシュしますが、それがtrueになることを示していますが、チェックボックスが表示されるため、1が増加してから目的の位置になり、クラッシュします。_positionitemList"free text"if (itemList.get(_position).getType().compareTo(Question.TYPE_CATEGORY) == 0)rowView.getTag()_position

    @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;
}

ビューホルダークラスは

static class 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;
}

痕跡

  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

score 2 · Accepted Answer

例外が発生しているのは、（さまざまなタイプの行の）さまざまなコードブランチがそれぞれ、任意の種類のタグオブジェクトが関連付けられている再利用された行ビューを処理している可能性があるためです。

Adapter最善の解決策は、getItemViewType(int)とメソッドをオーバーライドして、getViewTypeCount()使用しているさまざまなタイプのアイテムビューの数を指定し、それらをリストの位置にマップすることです。これにより、ロジックが簡素化され、ビュータイプごとに行リサイクルプールを異なる方法で処理できるgetView(...)ようになります。ListView

getView(...)テストを次のようなものに変更できます。

if (getItemViewType(_position) == TYPE_CATEGORY) {
   // code for categories
}

Adapterサブクラスが知っているTYPE_CATEGORYのはどこですか。int

android - リストビューでViewHolderを使用するとプログラムがクラッシュする

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