listview中的第一个progressBar没有进展

Question

我有一个非常糟糕的问题。 我有一个带有适配器的列表视图。

public class MediaAdapter extends  ArrayAdapter<Media> {


public MediaAdapter(Context context, Media[] items) {
    super(context, R.layout.mediaitemlist, items);
}

/* private view holder class */
private class ViewHolder {
    TextView media_name;
    TextView media_path;
    TextView media_version;
    TextView media_type;
    ProgressBar pb;
}   

public View getView(int position, View convertView, ViewGroup parent) {
    ViewHolder holder = null;
    View view = convertView;
    if (view == null) {
        view = (View)LayoutInflater.from(getContext()).inflate(R.layout.mediaitemlist, null);
        holder = new ViewHolder();
        holder.media_name = (TextView) view
                .findViewById(R.id.media_name);
        holder.media_path = (TextView) view
                .findViewById(R.id.media_path);
        holder.media_type = (TextView) view
                .findViewById(R.id.media_type);
        holder.media_version = (TextView) view
                .findViewById(R.id.media_version);
        holder.pb = (ProgressBar)view.findViewById(R.id.itemprogressdl);
        view.setTag(holder);

        //Maybe the problem is here ???????????
        getItem(position).setmProgressBar((ProgressBar)view.findViewById(R.id.itemprogressdl));
    } else {
        holder = (ViewHolder) view.getTag();
    }

    Media rowItem = (Media) getItem(position);

    holder.media_name.setText(rowItem.get_Name());
    holder.media_path.setText(rowItem.get_Path());
    holder.media_type.setText(rowItem.get_TypeString());
    holder.media_version.setText("" + rowItem.get_Version());
    rowItem.setmProgressBar(holder.pb);
    return view;
}

}

这里是 mediaitemlist 布局：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="10dp"
android:background="@drawable/listitembackground" >

<TextView
    android:id="@+id/media_name"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentLeft="true"
    android:layout_alignParentTop="true"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:textColor="@android:color/black"
    android:textSize="25sp" />

<TextView
    android:id="@+id/media_path"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentLeft="true"
    android:layout_alignParentRight="true"
    android:layout_below="@+id/media_name"
    android:textColor="@android:color/black"
    android:visibility="invisible" />

<TextView
    android:id="@+id/media_version"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentRight="true"
    android:layout_alignParentTop="true"
    android:textColor="@android:color/black" />

<TextView
    android:id="@+id/media_type"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentTop="true"
    android:layout_marginRight="20dp"
    android:layout_toLeftOf="@+id/media_version"
    android:textColor="@android:color/black" />

<ProgressBar
    android:id="@+id/itemprogressdl"
    style="?android:attr/progressBarStyleHorizontal"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignLeft="@+id/media_name"
    android:layout_below="@+id/media_name"
    android:layout_toLeftOf="@+id/media_version" 
    android:max="100"
    android:visibility="invisible"
    android:indeterminate="true"/>

</RelativeLayout>

progressBar 是一个媒体类的属性。一个 Media 类根据他在 listView 中的位置有自己的进度。

但是，所有的progressBar 属性都很好，除了listView 的第一个。如果我点击第二个或更多，我可以看到 progressBar 进度，但不是第一个。

那么，为什么第一个progressBar 不起作用，而下一个起作用呢？

如果您需要更多代码、cmets 或其他，请询问我。

Answer 1

试着移动这条线

getItem(position).setmProgressBar((ProgressBar)view.findViewById(R.id.itemprogressdl));

超出 if..else 条件。

Answer 2

试试这个答案：

public View getView(int position, View convertView, ViewGroup parent) {
    ViewHolder holder = null;
    View view = convertView;
    Media rowItem = (Media) getItem(position);
    if (view == null) {
        view = (View)LayoutInflater.from(getContext()).inflate(R.layout.mediaitemlist, null);
        holder = new ViewHolder();
        holder.media_name = (TextView) view
                .findViewById(R.id.media_name);
        holder.media_path = (TextView) view
                .findViewById(R.id.media_path);
        holder.media_type = (TextView) view
                .findViewById(R.id.media_type);
        holder.media_version = (TextView) view
                .findViewById(R.id.media_version);
        holder.pb = (ProgressBar)view.findViewById(R.id.itemprogressdl);
        view.setTag(holder);

        //Maybe the problem is here ???????????
        getItem(position).setmProgressBar((ProgressBar)view.findViewById(R.id.itemprogressdl));
    } else {
        holder = (ViewHolder) view.getTag();
        rowItem.setmProgressBar(holder.pb);
    }

    holder.media_name.setText(rowItem.get_Name());
    holder.media_path.setText(rowItem.get_Path());
    holder.media_type.setText(rowItem.get_TypeString());
    holder.media_version.setText("" + rowItem.get_Version());

    return view;
}