本文介绍了尝试在 SimpleCursorAdapter 中覆盖 getView 会导致 NullPointerExceptio的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
非常感谢任何有关下一步的帮助或提示.
Would very much appreciate any help or hint on were to go next.
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.
I'm trying to change the content of a row in ListView programmatically. In one row there are 3 TextView and a ProgressBar. I want to animate the ProgressBar if the 'result' column of the current row is zero.
阅读一些教程和文档后，我得出的结论是必须使用 LayoutInflater 并且 getView() - 覆盖.也许我错了.
After reading some tutorials and docs, I came to the conclusion that LayoutInflater has to be used and getView() - overriden. Maybe I am wrong on this.
如果我从函数返回 row = inflater.inflate(R.layout.row, null);，它会给出 NullPointerException.
If I return row = inflater.inflate(R.layout.row, null); from the function, it gives 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)
推荐答案
对于 CursorAdapter 和子类，你应该重写 newView() 和 bindView() 而不是 getView().
For CursorAdapter and subclasses, you should override newView() and bindView() instead of getView().
但更重要的是，您不应调用 super.getView().那就是你崩溃的地方.
More importantly, though, you should not get calling super.getView(). That is where you are crashing.
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