Question

当我尝试使用expandable getgroupview方法在textview中设置值时，我遇到了一些错误。请建议做什么，因为我无法设置值

   @Override
public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {

    CommentModel commentModel = (CommentModel) getGroup(groupPosition);

    ViewHolder viewholder=null;
    if (convertView==null) {

        LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        inflater.inflate(R.layout.commentparent,null);
        viewholder = new ViewHolder();
        Log.i("MYNEWSAMSING",commentModel.getContent());
        viewholder.parentname = (TextView) convertView.findViewById(R.id.parentname);

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

    }
      viewholder.parentname.setText(commentModel.getContent());


    return convertView;
}

这是我在运行程序时得到的错误。

E/AndroidRuntime: FATAL EXCEPTION: main
                                             Process: com.mytrendin.simple, PID: 8149
                                             java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.view.View.findViewById(int)' on a null object reference
                                                 at com.mytrendin.simple.Expandablelistadapter.getGroupView(Expandablelistadapter.java:87)
                                                 at android.widget.ExpandableListConnector.getView(ExpandableListConnector.java:446)
                                                 at android.widget.AbsListView.obtainView(AbsListView.java:2362)
                                                 at android.widget.ListView.measureHeightOfChildren(ListView.java:1326)
                                                 at android.widget.ListView.onMeasure(ListView.java:1233)
                                                 at android.view.View.measure(View.java:19734)
                                                 at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6120)
                                                 at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1464)
                                                 at android.widget.LinearLayout.measureVertical(LinearLayout.java:758)
                                                 at android.widget.LinearLayout.onMeasure(LinearLayout.java:640)
                                                 at android.view.View.measure(View.java:19734)
                                                 at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6120)
                                                 at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
                                                 at android.view.View.measure(View.java:19734)
                                                 at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6120)
                                                 at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1464)
                                                 at android.widget.LinearLayout.measureVertical(LinearLayout.java:758)
                                                 at android.widget.LinearLayout.onMeasure(LinearLayout.java:640)
                                                 at android.view.View.measure(View.java:19734)
                                                 at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6120)
                                                 at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
                                                 at com.android.internal.policy.DecorView.onMeasure(DecorView.java:687)
                                                 at android.view.View.measure(View.java:19734)
                                                 at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2271)
                                                 at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1358)
                                                 at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1607)
                                                 at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1246)
                                                 at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6301)
                                                 at android.view.Choreographer$CallbackRecord.run(Choreographer.java:871)
                                                 at android.view.Choreographer.doCallbacks(Choreographer.java:683)
                                                 at android.view.Choreographer.doFrame(Choreographer.java:619)
                                                 at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:857)
                                                 at android.os.Handler.handleCallback(Handler.java:751)
                                                 at android.os.Handler.dispatchMessage(Handler.java:95)
                                                 at android.os.Looper.loop(Looper.java:154)
                                                 at android.app.ActivityThread.main(ActivityThread.java:6077)
                                                 at java.lang.reflect.Method.invoke(Native Method)
                                                 at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865)
                                                 at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)

0

Answer 1

问题出在if语句中。

如果看到代码，则在下面的语句中，convertView为null

viewholder.parentname = (TextView) convertView.findViewById(R.id.parentname);

以下是if条件的正确实现：

LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
convertView = inflater.inflate(R.layout.commentparent,null);
viewholder = new ViewHolder();
Log.i("MYNEWSAMSING",commentModel.getContent());
viewholder.parentname = (TextView) convertView.findViewById(R.id.parentname);
convertView.setTag(viewholder);

Answer 2

您尚未引用 View 方法返回的 inflate() 。在 View

中保留 convertView 对象

更改为以下内容：

if (convertView==null) {

    LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    convertView = inflater.inflate(R.layout.commentparent,null);
    viewholder = new ViewHolder();
    Log.i("MYNEWSAMSING",commentModel.getContent());
    viewholder.parentname = (TextView) convertView.findViewById(R.id.parentname);

    convertView.setTag(viewholder);
}

如何使用Expandablelistview在文本视图中设置值

2 个答案: