Question

我正在尝试修改Google样本http://developer.android.com/training/displaying-bitmaps/process-bitmap.html。此示例使用asynctask从Internet获取图像并在gridview中显示。我想要做的是在图像下方显示文字。我得到例外java.lang.ClassCastException: android.widget.AbsListView$LayoutParams cannot be cast to android.widget.LinearLayout$LayoutParams

以下是代码：

getView方法

@Override
public View getView(int position, View convertView, ViewGroup container) {
    //BEGIN_INCLUDE(load_gridview_item)
    // First check if this is the top row
    if (position < mNumColumns) {
        if (convertView == null) {
            convertView = new View(mContext);
        }
        // Set empty view with height of ActionBar
        convertView.setLayoutParams(new AbsListView.LayoutParams(
                LayoutParams.MATCH_PARENT, mActionBarHeight));
        return convertView;
    }

    // Now handle the main ImageView thumbnails
    View vi = convertView;
    LayoutInflater inflater = (LayoutInflater) mContext
            .getSystemService(Context.LAYOUT_INFLATER_SERVICE);

    if (convertView == null)  // if it's not recycled, instantiate and initialize

        vi = inflater.inflate(R.layout.row_grid, null);
        TextView textView = (TextView) vi.findViewById(R.id.grid_text);
        ImageView imageView = (ImageView) vi.findViewById(R.id.grid_image);
        textView.setText("Sample text");
        //imageView = new RecyclingImageView(mContext);
        imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
        imageView.setLayoutParams(mImageViewLayoutParams);


        // Check the height matches our calculated column width
    if (imageView.getLayoutParams().height != mItemHeight) {
        imageView.setLayoutParams(mImageViewLayoutParams);
    }

        // Finally load the image asynchronously into the ImageView, this also takes care of
        // setting a placeholder image while the background thread runs
        mImageFetcher.loadImage(Images.imageThumbUrls()[position - mNumColumns], imageView);
        return vi;
        //END_INCLUDE(load_gridview_item)

}

异常

java.lang.ClassCastException：android.widget.AbsListView $ LayoutParams无法强制转换为android.widget.LinearLayout $ LayoutParams 在android.widget.LinearLayout.measureVertical（LinearLayout.java:651）在android.widget.LinearLayout.onMeasure（LinearLayout.java:558）在android.view.View.measure（View.java:12853）在android.widget.GridView.setupChild（GridView.java:1425）在android.widget.GridView.makeAndAddView（GridView.java:1342）在android.widget.GridView.makeRow（GridView.java:344）在android.widget.GridView.fillDown（GridView.java:286）在android.widget.GridView.fillFromTop（GridView.java:419）在android.widget.GridView.layoutChildren（GridView.java:1231）在android.widget.AbsListView.onLayout（AbsListView.java:1875）在android.view.View.layout（View.java:11390）在android.view.ViewGroup.layout（ViewGroup.java:4332）在android.widget.LinearLayout.setChildFrame（LinearLayout.java:1653）在android.widget.LinearLayout.layoutHorizontal（LinearLayout.java:1642）在android.widget.LinearLayout.onLayout（LinearLayout.java:1418）在android.view.View.layout（View.java:11390）在android.view.ViewGroup.layout（ViewGroup.java:4332）在android.widget.FrameLayout.onLayout（FrameLayout.java:444）在android.view.View.layout（View.java:11390）在android.view.ViewGroup.layout（ViewGroup.java:4332）在android.widget.FrameLayout.onLayout（FrameLayout.java:444）在android.view.View.layout（View.java:11390）在android.view.ViewGroup.layout（ViewGroup.java:4332）在android.widget.FrameLayout.onLayout（FrameLayout.java:444）在android.view.View.layout（View.java:11390）在android.view.ViewGroup.layout（ViewGroup.java:4332）在android.widget.FrameLayout.onLayout（FrameLayout.java:444）在android.view.View.layout（View.java:11390）在android.view.ViewGroup.layout（ViewGroup.java:4332）在android.view.ViewRootImpl.performTraversals（ViewRootImpl.java:1490）在android.view.ViewRootImpl.handleMessage（ViewRootImpl.java:2455）在android.os.Handler.dispatchMessage（Handler.java:99）在android.os.Looper.loop（Looper.java:137）在android.app.ActivityThread.main（ActivityThread.java:4424） at java.lang.reflect.Method.invokeNative（Native Method）在java.lang.reflect.Method.invoke（Method.java:511）在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:817）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:584）在dalvik.system.NativeStart.main（本地方法）
ImageGridFragment.xml

<GridView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/gridView"
    style="@style/PhotoGridLayout"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:columnWidth="@dimen/image_thumbnail_size"
    android:horizontalSpacing="@dimen/image_thumbnail_spacing"
    android:numColumns="auto_fit"
    android:stretchMode="columnWidth"
    android:verticalSpacing="@dimen/image_thumbnail_spacing" >

</GridView>

row_gridview.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:padding="5dp"
    android:orientation="vertical">
    <ImageView
        android:id="@+id/grid_image"
        android:layout_width="50dp"
        android:layout_height="50dp"
        android:background="#FF0000"/>
    <TextView
        android:id="@+id/grid_text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="15dp"
        android:textSize="9sp"/>

</LinearLayout>

Answer 1

尝试使用

convertView.setLayoutParams(new LinearLayout.LayoutParams(
            LayoutParams.MATCH_PARENT, mActionBarHeight));

而不是

convertView.setLayoutParams(new AbsListView.LayoutParams(
            LayoutParams.MATCH_PARENT, mActionBarHeight));

在Android ClassCastException中的GridView

1 个答案: