Android Java AppCompatTextView 无法转换为 LinearLayout

Question

我在尝试将多个文本视图添加到网格视图单元格时遇到了一些问题。文本视图的数量是动态的，它取决于数据库中的数据。以下是我为网格视图设置适配器的方法：

 adapter = new ArrayAdapter<String>(this.getContext(), android.R.layout.simple_list_item_1, items) {
 @Override
 public View getView(int position, View convertView, ViewGroup parent) {
     LinearLayout ll = (LinearLayout) super.getView(position, convertView, parent);
     
            // for simplicity I hardcoded two text views

            TextView cell = new TextView(this.getContext());
            cell.setText("Test");
            
            TextView cell2 = new TextView(this.getContext());
            cell2.setText("HI");

            ll.addView(cell);
            ll.addView(cell2);

            return ll;
        }
    };

    gridView.setAdapter(adapter);

我用于网格视图的 .xml 文件：

<GridView
    android:id="@+id/gridView"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:numColumns="7"
    android:requiresFadingEdge="vertical"
    android:scrollbars="none"
/>

但是，我收到以下错误消息：

java.lang.ClassCastException: android.support.v7.widget.AppCompatTextView cannot be cast to android.widget.LinearLayout
        at com.mainapp.scheduler.InstrumentSchedulerFragment$3.getView(InstrumentSchedulerFragment.java:586)
        at android.widget.AbsListView.obtainView(AbsListView.java:2365)
        at android.widget.GridView.onMeasure(GridView.java:1065)
        at android.view.View.measure(View.java:22071)
        at android.support.constraint.ConstraintLayout.internalMeasureChildren(ConstraintLayout.java:1212)
        at android.support.constraint.ConstraintLayout.onMeasure(ConstraintLayout.java:1552)
        at android.view.View.measure(View.java:22071)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6602)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
        at android.view.View.measure(View.java:22071)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6602)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
        at android.view.View.measure(View.java:22071)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6602)
        at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1514)
        at android.widget.LinearLayout.measureVertical(LinearLayout.java:806)
        at android.widget.LinearLayout.onMeasure(LinearLayout.java:685)
        at android.view.View.measure(View.java:22071)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6602)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
        at com.android.internal.policy.DecorView.onMeasure(DecorView.java:724)
        at android.view.View.measure(View.java:22071)
        at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2422)
        at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1504)
        at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1761)
        at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1392)
        at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6752)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:911)
        at android.view.Choreographer.doCallbacks(Choreographer.java:723)
        at android.view.Choreographer.doFrame(Choreographer.java:658)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:897)
        at android.os.Handler.handleCallback(Handler.java:790)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:164)
        at android.app.ActivityThread.main(ActivityThread.java:6494)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)

任何想法为什么会这样？

某些单元格只需要一个文本视图。但其他一些可能需要 2 到 3 次以上的文本视图。

Answer 1

您可以检查simple_list_item_1.xml 并查看它的根是否为TextView。如果是，它将根据您的示例抛出ClassCastException。

Answer 2

创建一个 xml 布局（例如 cell_layout.xml）并按照您希望单元格的外观对其进行设置。使用 LinearLayout 并在其中放置两个 TextView。给出两个 TextView 的 ID（例如 TextView1、TextView2）。创建 ArrayAdapter 时，请使用：new ArrayAdapter(this, R.layout.cell_layout)。

        //Add text for each cell to a string array
        String[] cell0 = new String[] {"Test", "Hi"};
        //Add all cells to an another string array
        String[][] cells = new String[][] {cell0};
        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            View cellView = convertView;
            if(cellView != null) {
                LayoutInflater layoutInflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                cellView = layoutInflater.inflate(R.layout.scores, parent);
            }
            cellView.findViewById(R.id.textView1).setText(cells[position][0]);
            cellView.findViewById(R.id.textView2).setText(cells[position][1]);
            return cellView;
        }

        //This is a shortcut. Normally you would create a custom ArrayAdapter and a custom class