Question

我一直在寻找和寻找解决这个错误一段时间,我似乎无法找出原因和如何解决这个问题。

我正在使用一个自定义的应用程序来填充我的列表视图。我将描述我的列表的 xml 放大。我用 FindViewById 来制作浏览器对象并装入我的文本视图。在此之后, 我想设置文本视图的文本, 但是它会发现 Viewbyid 返回一个无效值。所以自动解析成一个无效点例外。

适应器 :

/** CLASS : Custom Adapter for the listview */
private class CustomAdapter extends ArrayAdapter<Track>{
    private List<Track> items;
    private Context mContext;
    private int layoutResourceId;       
    private ViewHolder mHolder;

    public CustomAdapter(Context context, int layoutId, List<Track> objects) {
        super(context, layoutId, objects);
        layoutResourceId=layoutId;
        items = objects;
        mContext=context;       
    }       

    public View getView(int position, View convertView, ViewGroup parent) {
         if(convertView == null){
             LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
             convertView = inflater.inflate(layoutResourceId, parent, false);
             mHolder = new ViewHolder();
             ****** RETURNS NULL DURING DEBUGGING ******
             mHolder.textViewCenter = (TextView)findViewById(R.id.textview_list_item_central);
             convertView.setTag(mHolder);
         }else{
             mHolder = (ViewHolder) convertView.getTag();
         }
         Track track = items.get(position);
         ****** ERROR HAPPENS HERE ******
         mHolder.textViewCenter.setText(track.getTrack());
         return convertView;
    }

    class ViewHolder{
        ImageView imageView;
        TextView textViewCenter;
        TextView textViewRight;
    }
}

XML: (笑) (笑) (笑) (笑) (笑) (笑) (笑) (笑) (笑) (笑) (笑) (笑) (笑) (笑) (笑) (笑) (笑) (笑) (笑) (笑) (笑) (笑) (笑) (笑) (笑) (笑) (笑) (笑) (笑) (笑) (笑) (笑) (笑)

?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="horizontal" >

<ImageView
    android:id="@+id/imageview_list_albumart_icon"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="left"
    android:src="@drawable/ic_music" />

<TextView
    android:id="@+id/textview_list_item_central"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center"
    android:layout_weight="0.5"
    android:text="Center"
    android:textSize="20sp" >
</TextView>

<TextView
    android:id="@+id/textview_list_item_right"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="right"
    android:paddingRight="10dip"
    android:text="Right" />

任何帮助都感激不尽!

Answer 1

搜索您在 convertView 中膨胀的 convertView 中的观点(而不是像您目前所做的那样在当前 Aactivity 布局中搜索 ) :

 mHolder.textViewCenter = (TextView) 
                convertView.findViewById(R.id.textview_list_item_central);

Answer 2

您正在膨胀布局, 但取取它视图时不使用它。

做到这一点 :

 mHolder.textViewCenter = (TextView)convertView.findViewById(R.id.textview_list_item_central)

Answer 3

TextView 初始化错误

if(convertView == null){
             LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
             convertView = inflater.inflate(layoutResourceId, parent, false);
             mHolder = new ViewHolder();
             ****** RETURNS NULL DURING DEBUGGING ******
             mHolder.textViewCenter = (TextView) convertView .findViewById(R.id.textview_list_item_central); //Change done
             convertView.setTag(mHolder);
         }else{
             mHolder = (ViewHolder) convertView.getTag();
         }

Answer 4

更改线条

mHolder.textViewCenter = (TextView)findViewById(R.id.textview_list_item_central);

which is below * RETURNS NULL DURING DEBUGGING * by

mHolder.textViewCenter = (TextView) convertView.findViewById(R.id.textview_list_item_central);

Answer 5

尝试替换此 :

convertView = inflater.inflate(R.layout.listitemview, null);

where listitemview is your xml in which you defined your ImageView and TextViews..
hope this helps you

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