Imageview 无法通过列表视图适配器正确显示

Question

在我的适配器中，我有三种不同的视图，分别使用黄色、橙色和红色作为不同的文本颜色。为了配合这些，我尝试将三个不同的图像作为缩略图（hhy、hho、hhr）。当它运行时，图像与其相应的视图项目不匹配，我在列表视图中得到 hho 和 hhy 中的一个项目太早或太晚。我的 imageview 布局名称是正确的，所以我不确定为什么它们显示不正确。

PostItemAdapter.java

@Override
    public View getView(int position, View convertView, ViewGroup parent)
    {
        ViewHolder viewHolder;
        int listViewItemType = getItemViewType(position);

        if (convertView == null) {
            convertView = inflater.inflate(R.layout.postitem, null);

            viewHolder = new ViewHolder();
            //viewHolder.itemThumbView = (ImageView) convertView.findViewById(R.id.itemThumb);

            if (listViewItemType == TYPE_short) {
                viewHolder.itemTitleView = (TextView) convertView.findViewById(R.id.itemTitleLabel);
                viewHolder.itemThumbView = (ImageView) convertView.findViewById(R.id.itemThumb);
            } else if (listViewItemType == TYPE_med) {
                viewHolder.itemTitleView = (TextView) convertView.findViewById(R.id.itemTitleLabel1);
                viewHolder.itemThumbView = (ImageView) convertView.findViewById(R.id.itemThumb1);
            } else {
                viewHolder.itemTitleView = (TextView) convertView.findViewById(R.id.itemTitleLabel2);
                viewHolder.itemThumbView = (ImageView) convertView.findViewById(R.id.itemThumb2);
            }
            convertView.setTag(viewHolder);
        } else {
            viewHolder = (ViewHolder) convertView.getTag();
        }

        if (listViewItemType == TYPE_short) {
            viewHolder.itemTitleView.setText(datas.get(position).itemTitle);
            viewHolder.itemThumbView.setImageResource(R.drawable.hhy);
        } else if (listViewItemType == TYPE_med) {
            viewHolder.itemTitleView.setText(datas.get(position).itemTitle);
            viewHolder.itemThumbView.setImageResource(R.drawable.hho);
        } else {
            viewHolder.itemTitleView.setText(datas.get(position).itemTitle);
            viewHolder.itemThumbView.setImageResource(R.drawable.hhr);
        }

        return convertView;
    }
}

和相关布局postitem.xml

 <ImageView
        android:id="@+id/itemThumb"
        android:layout_width="48dp"
        android:layout_height="48dp"
        android:src="@drawable/hhy"
        android:scaleType="centerCrop"
        android:layout_marginRight="5dp"/>

    <ImageView
        android:id="@+id/itemThumb1"
        android:layout_width="48dp"
        android:layout_height="48dp"
        android:src="@drawable/hho"
        android:scaleType="centerCrop"
        android:layout_marginRight="5dp"/>

    <ImageView
        android:id="@+id/itemThumb2"
        android:layout_width="48dp"
        android:layout_height="48dp"
        android:src="@drawable/hhr"
        android:scaleType="centerCrop"
        android:layout_marginRight="5dp"/>

    <TextView
        android:id="@+id/itemTitleLabel"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:layout_alignTop="@id/itemThumb"
        android:layout_toRightOf="@id/itemThumb"
        android:maxLines="2"
        android:textIsSelectable="false"
        android:textSize="16sp"
        android:textStyle="bold"
        android:textColor="#ffff00"
        android:ellipsize="end"
        />

    <TextView
        android:id="@+id/itemTitleLabel1"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:layout_alignTop="@id/itemThumb"
        android:layout_toRightOf="@id/itemThumb"
        android:maxLines="2"
        android:textIsSelectable="false"
        android:textSize="16sp"
        android:textStyle="bold"
        android:textColor="#ffa500"
        android:ellipsize="end"
         />

    <TextView
        android:id="@+id/itemTitleLabel2"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:layout_alignTop="@id/itemThumb"
        android:layout_toRightOf="@id/itemThumb"
        android:maxLines="2"
        android:textIsSelectable="false"
        android:textSize="16sp"
        android:textStyle="bold"
        android:textColor="#ff0000"
        android:ellipsize="end"
         />

正在发生的事情的图像；

Answer 1

好的，我的问题是，当回收列表视图视图时，它们覆盖或无法覆盖预先存在的 image/text。我相当老套的解决方案是使用以下代码。如果有人知道您应该如何解决这个问题，我很想听听：P

PostItemAdapter.java (ViewHolder)

 static class ViewHolder
    {
        private TextView itemTitleViewY, itemTitleViewO, itemTitleViewR;
        private ImageView itemThumbViewY, itemThumbViewO, itemThumbViewR;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent)
    {
        ViewHolder viewHolder;
        Item i = datas.get(position);
        int listViewItemType = i.viewtype;

        if (convertView == null) {
            convertView = inflater.inflate(R.layout.postitem, null);

            viewHolder = new ViewHolder();

            viewHolder.itemTitleViewY = (TextView) convertView.findViewById(R.id.itemTitleLabel);
            viewHolder.itemThumbViewY = (ImageView) convertView.findViewById(R.id.itemThumb);
            viewHolder.itemTitleViewO = (TextView) convertView.findViewById(R.id.itemTitleLabel1);
            viewHolder.itemThumbViewO = (ImageView) convertView.findViewById(R.id.itemThumb1);
            viewHolder.itemTitleViewR = (TextView) convertView.findViewById(R.id.itemTitleLabel2);
            viewHolder.itemThumbViewR = (ImageView) convertView.findViewById(R.id.itemThumb2);

            convertView.setTag(viewHolder);
        } else {
            viewHolder = (ViewHolder) convertView.getTag();
        }

        switch (listViewItemType) {
            case 0:
                viewHolder.itemTitleViewY.setText(i.itemTitle);
                viewHolder.itemTitleViewO.setText("");
                viewHolder.itemTitleViewR.setText("");
                viewHolder.itemThumbViewY.setVisibility(View.VISIBLE);
                viewHolder.itemThumbViewO.setVisibility(View.INVISIBLE);
                viewHolder.itemThumbViewR.setVisibility(View.INVISIBLE);
                Log.d("DEBUG CHECKME", "getItemViewType Y: " + i.itemTitle + ", " + i.viewtype + ", " + i);
                break;
            case 1:
                viewHolder.itemTitleViewO.setText(i.itemTitle);
                viewHolder.itemTitleViewY.setText("");
                viewHolder.itemTitleViewR.setText("");
                viewHolder.itemThumbViewO.setVisibility(View.VISIBLE);
                viewHolder.itemThumbViewY.setVisibility(View.INVISIBLE);
                viewHolder.itemThumbViewR.setVisibility(View.INVISIBLE);
                Log.d("DEBUG CHECKME", "getItemViewType O: " + i.itemTitle + ", " + i.viewtype + ", " + i);
                break;
            case 2:
                viewHolder.itemTitleViewR.setText(i.itemTitle);
                viewHolder.itemTitleViewO.setText("");
                viewHolder.itemTitleViewY.setText("");
                viewHolder.itemThumbViewR.setVisibility(View.VISIBLE);
                viewHolder.itemThumbViewY.setVisibility(View.INVISIBLE);
                viewHolder.itemThumbViewO.setVisibility(View.INVISIBLE);
                Log.d("DEBUG CHECKME", "getItemViewType R: " + i.itemTitle + ", " + i.viewtype + ", " + i);
                break;
            default:
                viewHolder.itemTitleViewY.setText("");
                viewHolder.itemTitleViewO.setText("");
                viewHolder.itemTitleViewR.setText("");
                viewHolder.itemThumbViewY.setVisibility(View.INVISIBLE);
                viewHolder.itemThumbViewO.setVisibility(View.INVISIBLE);
                viewHolder.itemThumbViewR.setVisibility(View.INVISIBLE);
                Log.d("DEBUG CHECKME", "getItemViewType D: " + i.itemTitle + ", " + i.viewtype + ", " + i);
                break;
        }
        return convertView;
    }

Answer 2

您的问题中存在一些问题。回收视图仅 inflated/created 次足以首次完全填充 ListView 的可见部分。然后在您滚动时回收它们，而不是重新创建它们。

这意味着这个块只被调用了前几次：

if (convertView == null) {
        convertView = inflater.inflate(R.layout.postitem, null);

        viewHolder = new ViewHolder();
        //viewHolder.itemThumbView = (ImageView) convertView.findViewById(R.id.itemThumb);

        if (listViewItemType == TYPE_short) {
            viewHolder.itemTitleView = (TextView) convertView.findViewById(R.id.itemTitleLabel);
            viewHolder.itemThumbView = (ImageView) convertView.findViewById(R.id.itemThumb);
        } else if (listViewItemType == TYPE_med) {
            viewHolder.itemTitleView = (TextView) convertView.findViewById(R.id.itemTitleLabel1);
            viewHolder.itemThumbView = (ImageView) convertView.findViewById(R.id.itemThumb1);
        } else {
            viewHolder.itemTitleView = (TextView) convertView.findViewById(R.id.itemTitleLabel2);
            viewHolder.itemThumbView = (ImageView) convertView.findViewById(R.id.itemThumb2);
        }
        convertView.setTag(viewHolder);
    }

对于后续的回收，您的 ViewHolder 可能指向了一个非预期的资源。如果当前项目是 TYPE_med，则 viewHolder.itemThumbView 可能是使用不同的资源引用创建的（即创建时的 TYPE_short）。解决这个问题仍然无法解决您的问题，因为您还有另外两个 ImageViews/TextViews 闲逛。

我看不出有任何明显的需要多个 ImageViews/TextViews 因此，与其设置所有内容的可见性，更可接受的方法是：

static class ViewHolder
{
    private TextView mTextViewTitle;
    private ImageView mImageViewThumb;
}

@Override
public View getView(int position, View convertView, ViewGroup parent)
{
    ViewHolder viewHolder;
    Item i = datas.get(position);
    int listViewItemType = i.viewtype;

    if (convertView == null) {
        convertView = inflater.inflate(R.layout.postitem, null);

        viewHolder = new ViewHolder();

        viewHolder.mTextViewTitle = (TextView) convertView.findViewById(R.id.itemTitleLabel);
        viewHolder.mImageViewThumb = (ImageView) convertView.findViewById(R.id.itemThumb);

        convertView.setTag(viewHolder);
    } else {
        viewHolder = (ViewHolder) convertView.getTag();
    }

    viewHolder.mTextViewTitle.setText(i.itemTitle);

    if (listViewItemType == TYPE_short) {
        viewHolder.mTextViewTitle.setTextColor(Color.parseColor("#ffff00"));
        viewHolder.mImageViewThumb.setImageResource(R.drawable.hhy);
    } else if (listViewItemType == TYPE_med) {
        viewHolder.mTextViewTitle.setTextColor(Color.parseColor("#ffff00"));
        viewHolder.mImageViewThumb.setImageResource(R.drawable.hho);
    } else {
        viewHolder.mTextViewTitle.setTextColor(Color.parseColor("#ff0000"));
        viewHolder.mImageViewThumb.setImageResource(R.drawable.hhr);
    }

    return convertView;
}

最好在资源中定义您的颜色，但我会把它留到下次讨论。

你的新 XML:

<ImageView
    android:id="@+id/itemThumb"
    android:layout_width="48dp"
    android:layout_height="48dp"
    android:scaleType="centerCrop"
    android:layout_marginRight="5dp" />

<TextView
    android:id="@+id/itemTitleLabel"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:layout_alignParentRight="true"
    android:layout_alignTop="@id/itemThumb"
    android:layout_toRightOf="@id/itemThumb"
    android:maxLines="2"
    android:textIsSelectable="false"
    android:textSize="16sp"
    android:textStyle="bold"
    android:ellipsize="end" />

Imageview 无法通过列表视图适配器正确显示

Imageview not displaying correctly through listview adapter

android

listview

adapter

imageview