android - 尝试覆盖 SimpleCursorAdapter 中的 getView 会给出 NullPointerException

Question

非常感谢任何关于下一步的帮助或提示。

我正在尝试以编程方式更改 ListView 中一行的内容。在一行中有 3 个 TextView 和一个 ProgressBar。如果当前行的“结果”列为零，我想为 ProgressBar 设置动画。

在阅读了一些教程和文档之后，我得出的结论是必须使用 LayoutInflater 并覆盖 getView()。也许我错了。

如果我从函数返回 row = inflater.inflate(R.layout.row, null);，它会给出 NullPointerException。

代码如下:

    private final class mySimpleCursorAdapter extends SimpleCursorAdapter {

    private Cursor localCursor;
    private Context localContext;

    public mySimpleCursorAdapter(Context context, int layout, Cursor c, String[] from, int[] to) {
        super(context, layout, c, from, to);            
        this.localCursor = c;
        this.localContext = context;

    }

    /**
     *    1. ListView asks adapter "give me a view" (getView) for each item of the list
     *    2. A new View is returned and displayed
     */
    public View getView(int position, View  convertView, ViewGroup  parent) {
        View row = super.getView(position, convertView, parent);

        LayoutInflater inflater = (LayoutInflater)localContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

        String result = localCursor.getString(2);
        int resInt = Integer.parseInt(result);

        Log.d(TAG, "row " + row);

        // if 'result' column form the TABLE is 0, do something useful:
        if(resInt == 0) {           
            ProgressBar progress = (ProgressBar) row.findViewById(R.id.update_progress);
            progress.setIndeterminate(true);

            TextView edit1 = (TextView)row.findViewById(R.id.row_id);
            TextView edit2 = (TextView)row.findViewById(R.id.request);
            TextView edit3 = (TextView)row.findViewById(R.id.result);
            edit1.setText("1");
            edit2.setText("2");
            edit3.setText("3");
            row = inflater.inflate(R.layout.row, null);             
        }

        return row;
    }

这是堆栈跟踪:

03-08 03:15:29.639: ERROR/AndroidRuntime(619): java.lang.NullPointerException
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at android.widget.SimpleCursorAdapter.bindView(SimpleCursorAdapter.java:149)
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at android.widget.CursorAdapter.getView(CursorAdapter.java:186)
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at com.dhristov.test1.test1$mySimpleCursorAdapter.getView(test1.java:105)
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at android.widget.AbsListView.obtainView(AbsListView.java:1256)
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at android.widget.ListView.makeAndAddView(ListView.java:1668)
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at android.widget.ListView.fillDown(ListView.java:637)
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at android.widget.ListView.fillSpecific(ListView.java:1224)
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at android.widget.ListView.layoutChildren(ListView.java:1499)
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at android.widget.AbsListView.onLayout(AbsListView.java:1113)
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at android.view.View.layout(View.java:6830)
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1119)
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at android.widget.LinearLayout.layoutVertical(LinearLayout.java:998)
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at android.widget.LinearLayout.onLayout(LinearLayout.java:918)
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at android.view.View.layout(View.java:6830)
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1119)
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at android.widget.LinearLayout.layoutVertical(LinearLayout.java:998)
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at android.widget.LinearLayout.onLayout(LinearLayout.java:918)
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at android.view.View.layout(View.java:6830)
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at android.widget.FrameLayout.onLayout(FrameLayout.java:333)
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at android.view.View.layout(View.java:6830)
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1119)
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at android.widget.LinearLayout.layoutVertical(LinearLayout.java:998)
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at android.widget.LinearLayout.onLayout(LinearLayout.java:918)
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at android.view.View.layout(View.java:6830)
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at android.widget.FrameLayout.onLayout(FrameLayout.java:333)
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at android.view.View.layout(View.java:6830)
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at android.view.ViewRoot.performTraversals(ViewRoot.java:996)
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at android.view.ViewRoot.handleMessage(ViewRoot.java:1633)
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at android.os.Handler.dispatchMessage(Handler.java:99)
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at android.os.Looper.loop(Looper.java:123)
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at android.app.ActivityThread.main(ActivityThread.java:4363)
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at java.lang.reflect.Method.invokeNative(Native Method)
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at java.lang.reflect.Method.invoke(Method.java:521)
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
03-08 03:15:29.639: ERROR/AndroidRuntime(619):     at dalvik.system.NativeStart.main(Native Method)

Answer 1

对于 CursorAdapter 和子类，您应该覆盖 newView() 和 bindView() 而不是 getView().

但更重要的是，您不应该调用 super.getView()。那就是你崩溃的地方。