Question

我想在SimpleAdapter使用ListView时添加一些自定义操作。所以我写了一个MySimpleAdapter来扩展SimpleAdapter。如果图片网址为空，我需要隐藏ImageView。但是，当视图回收工作时，具有可见ImageView的视图在向上和向下滚动时也会隐藏。

代码如下：

public class MySimpleAdapter extends SimpleAdapter {
  ...
  public View getView(int position, View convertView, ViewGroup parent) {
    View vi = convertView;        
    vi=super.getView(position, convertView, parent);//other parts rather than the ImageView will behave normally

    @SuppressWarnings("unchecked")
    HashMap<String, Object> data = (HashMap<String, Object>) getItem(position);

    //below is the problematic part
    if(data.get("url")!=null){
        setImageWithUrl(data.get("url").toString(), (ImageView) vi.findViewById(R.id.my_image));//setImageWithUrl is a function containing my extra operations
    }else{
        ((ImageView) vi.findViewById(R.id.my_image)).setVisibility(View.GONE);//hide the image as it has a border but no content
    }

    //in contrast, setting image drawable is always right
    if(data.get("url2")!=null){
        setImageWithUrl(data.get("url2").toString(), (ImageView) vi.findViewById(R.id.my_image_2));
    }else{
      ((ImageView)vi.findViewById(R.id.my_image_2)).setImageDrawable(mContext.getResources().getDrawable(R.drawable.default_image));
    }
  }
}

问题就像（例如屏幕显示ListView的 3 行：

[1=====] <a row with visible image
[2=====] <a row with visible image
[3=====] <a row with visible image
--------- below is out of screen
[4=====] <a row with hidden image

向下滚动到 4th 行，以便 1th 不在屏幕上。然后滚动回 1th 并且 4th 不在屏幕上。然后 1th 是隐藏图像@id/my_image的行。我认为这是由于＆＃34; findViewById＆＃34;。但是为什么用可绘制资源设置图像总是正确的（对于@id/my_image_2）？

我对inflater和回收机制的细节不太熟悉。如何在此代码中避免这种情况？或者我需要使用其他适配器吗？

PS，

行xml结构很简单，如：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical">
    <TextView
        android:id="@+id/title_text"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
    <ImageView
        android:id="@+id/my_image"
        android:layout_width="100dp"
        android:layout_height="100dp"
        android:background="@layout/border_style" />
    <ImageView
        android:id="@+id/my_image_2"
        android:layout_width="100dp"
        android:layout_height="100dp" />
    ...
</LinearLayout>

Answer 1

ListView重用视图，因此您需要实现隐藏/恢复逻辑。将集合可见性添加到代码中可见。

$rcrdID    = DB::table('dbo_studentrecord')
                ->join('dbo_students','dbo_studentrecord.StudentID' ,'=' ,'dbo_students.StudentID')
                ->lists(DB::raw('CONCAT("ID ", dbo_studentrecord.StudentID, "  |  " ,dbo_students.FirstName, " ", dbo_students.LastName)'),'StudentRecordID');

在自定义的SimpleAdapter中通过id调用视图？

1 个答案: