java - button.OnClick 代码运行但不执行更改？

Question

我正在尝试为图像按钮创建一个 OnClick 监听器，该监听器应该在单击时删除位图(将其设置为 null)。但是，当我按下按钮时，什么也没有发生，除了它确实打印了我的“Log.d()”消息，并且单击后位图实际上为空，但是没有显示更改。该代码写在我的适配器内。我什至尝试将其插入 runOnUIThread 中以查看是否有影响，但没有任何变化。我还尝试了 setImageDrawable(null) 和 setImageResource(0) 但没有成功。我什至尝试更改其他 UI 元素，但这也不起作用。我唯一能做的就是打印日志消息...

这是我的 getView 和 onClick 方法:

    @Override
public View getView(final int position, View convertView, ViewGroup parent)
{
    if (convertView == null)
    {
        LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        convertView = inflater.inflate(R.layout.item_create_product_gridview_normal, parent, false);
        //Set up viewholder
        viewHolder = new ViewHolder();
        viewHolder.productImageIv = (ImageView) convertView.findViewById(R.id.android_gridview_image);
        viewHolder.addImageIb = (ImageButton) convertView.findViewById(R.id.addImageButton);
        viewHolder.removeImageIb = (ImageButton) convertView.findViewById(R.id.removeImageButton);
        viewHolder.productImageIv.setImageBitmap(images[position]);
        checkForNullImages(viewHolder, position);
        //Store the holder with the view
        convertView.setTag(viewHolder);

        viewHolder.removeImageIb.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                runOnUiThread (new Thread(new Runnable() {
                    public void run() {
                        images[position] = null;
                        viewHolder.productImageIv.setImageBitmap(images[position]);
                        notifyDataSetChanged();
                        //Does print this message, item is null, but image is still shown
                        Log.e("LogMSG", "item should be null " + getItem(position));
                    }
                }));

            }
        });
    }
    return convertView;
}

如果相关的话，这是我相应的 XML:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/android_custom_gridview_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center_horizontal"
android:orientation="vertical">

<android.support.v7.widget.CardView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginTop="4dp"
    android:layout_marginBottom="4dp"
    app:cardCornerRadius="10dp"
    app:cardBackgroundColor="@color/white">

    <android.support.v7.widget.CardView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="2dp"
        app:cardCornerRadius="10dp">

        <ImageView
            android:id="@+id/android_gridview_image"
            android:layout_width="100dp"
            android:layout_height="100dp"
            android:background="@drawable/gradient_background"
            android:scaleType="centerCrop" />

    </android.support.v7.widget.CardView>

</android.support.v7.widget.CardView>

<ImageButton
    android:id="@+id/addImageButton"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginTop="-30dp"
    android:elevation="@dimen/standard_12"
    android:background="@drawable/icon_add" />

<ImageButton
    android:id="@+id/removeImageButton"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginTop="-30dp"
    android:background="@drawable/icon_remove"
    android:elevation="@dimen/standard_12" />

Answer 1

这是因为您的行 View 回收不正确。您不会使用以下代码回收 View :

@Override
public View getView(final int position, View convertView, ViewGroup parent)
{
    if (convertView == null)
    {
      // ...
    }

    return convertView;
}

因为如果之前的convertView不为空，那么您就不会使用它。

因此，将您的代码更改为如下所示:

@Override
public View getView(final int position, View convertView, ViewGroup parent)
{
    ViewHolder holder;
    if (convertView == null) {
       LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        convertView = inflater.inflate(R.layout.item_create_product_gridview_normal, parent, false);
        //Set up viewholder
        holder = new ViewHolder();
        holder.productImageIv = (ImageView) convertView.findViewById(R.id.android_gridview_image);
        holder.addImageIb = (ImageButton) convertView.findViewById(R.id.addImageButton);
        holder.removeImageIb = (ImageButton) convertView.findViewById(R.id.removeImageButton);

        // set click listener here.
        // don't use runOnUiThread for click listener.

        // bind the view here.

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

    // set the value for view here
    holder.productImageIv.setImageBitmap(images[position]);


    return convertView;
}