13

我有以下代码，试图在 ListView 中创建一个简单的 ListAdapter （我之前有这个代码工作，这是我唯一改变的地方）：

public BuddyListAdapter(Context context, HashMap<String, Buddy> hashMap) {
    buddyList = new ArrayList<Buddy>(hashMap.values());
    mInflater = LayoutInflater.from(context);
    ctx = context;
}

单步执行时，什么都没有发生，但是在运行时，我得到一个NullPointerExceptionin ChoreoGrapher.doCallbacks，当我创建一个 empty 时ArrayList，它不会崩溃：

public BuddyListAdapter(Context context, HashMap<String, Buddy> hashMap) {
    buddyList = new ArrayList<Buddy>();
    mInflater = LayoutInflater.from(context);
    ctx = context;
}

什么是它ChoreoGrapher，为什么它会导致我的应用程序崩溃？

我完全被困在可能是什么问题上，或者如何找出问题所在。Eclipse 调试器或崩溃信息并没有真正的帮助。

整个堆栈跟踪如下：

Thread [<1> main] (Suspended (exception NullPointerException))  
    Choreographer.doCallbacks(int, long) line: 558  
    Choreographer.doFrame(long, int) line: 525  
    Choreographer$FrameDisplayEventReceiver.run() line: 711 
    Handler.handleCallback(Message) line: 615   
    Choreographer$FrameHandler(Handler).dispatchMessage(Message) line: 92   
    Looper.loop() line: 137 
    ActivityThread.main(String[]) line: 4745    
    Method.invokeNative(Object, Object[], Class, Class[], Class, int, boolean) line: not available [native method]  
    Method.invoke(Object, Object...) line: 511  
    ZygoteInit$MethodAndArgsCaller.run() line: 786  
    ZygoteInit.main(String[]) line: 553 
    NativeStart.main(String[]) line: not available [native method]

我也有一个Handler主要活动。当它不做任何事情时，列表视图不会崩溃。但是，我在打开列表视图之前从中删除了所有回调。

4

3 回答 3

30

我的应用程序中只有 Android 4.4 才有这个错误。

在调试器中，它显示与提问者相同的消息。但是，当不调试 DDMS 中的完整堆栈跟踪时：

完整的堆栈跟踪：

11-13 16:34:53.088: E/AndroidRuntime(1964): FATAL EXCEPTION: main
11-13 16:34:53.088: E/AndroidRuntime(1964): Process: appname, PID: 1964
11-13 16:34:53.088: E/AndroidRuntime(1964): java.lang.NullPointerException
11-13 16:34:53.088: E/AndroidRuntime(1964):     at android.widget.TextView.makeNewLayout(TextView.java:6124)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at android.widget.TextView.onMeasure(TextView.java:6419)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at android.view.View.measure(View.java:16458)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at android.widget.Spinner.setUpChild(Spinner.java:632)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at android.widget.Spinner.makeView(Spinner.java:585)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at android.widget.Spinner.getBaseline(Spinner.java:431)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at android.widget.LinearLayout.measureHorizontal(LinearLayout.java:1262)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at android.widget.LinearLayout.onMeasure(LinearLayout.java:590)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at android.view.View.measure(View.java:16458)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at android.view.View.measure(View.java:16458)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at android.view.View.measure(View.java:16458)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at com.android.internal.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:327)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at android.view.View.measure(View.java:16458)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2289)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at android.view.View.measure(View.java:16458)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1914)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1111)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1293)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:998)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5582)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at android.view.Choreographer.doCallbacks(Choreographer.java:562)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at android.view.Choreographer.doFrame(Choreographer.java:532)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at android.os.Handler.handleCallback(Handler.java:733)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at android.os.Handler.dispatchMessage(Handler.java:95)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at android.os.Looper.loop(Looper.java:137)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at android.app.ActivityThread.main(ActivityThread.java:4998)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at java.lang.reflect.Method.invokeNative(Native Method)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at java.lang.reflect.Method.invoke(Method.java:515)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:593)
11-13 16:34:53.088: E/AndroidRuntime(1964):     at dalvik.system.NativeStart.main(Native Method)

翻看第6124行TextView的4.4源码，原来这是椭圆时缺少layout params造成的。这很奇怪，因为代码在 a 中失败ListAdapter，您没有在getView.

android.R.layout.simple_spinner_item我曾经为标准微调项目充气。看起来这个项目使用ellipsing. 所以getView我现在打电话给：

view.setEllipsize(null);

这解决了我在 Android 4.4 上的问题。

编辑

事实证明，问题不是椭圆，而是视图中的不当膨胀getView。

inflater.inflate(android.R.layout.simple_spinner_item, null);//WRONG
inflater.inflate(android.R.layout.simple_spinner_item, parent, false);//GOOD

请注意，您提供false的不是立即将视图附加到父级，因为这是在需要时附加子级的适配器中。否则你会得到错误。

当你正确充气时，你不需要设置ellipseSize为null. 这是因为当您使用父级填充好方法时，它会LayoutParams正确处理，导致椭圆代码不会 raise NullPointerException。

所以，适当地充气，然后你就不必再担心了。

于 2013-11-13T21:53:51.747 回答
7

我在另一个应用程序中再次遇到同样的事情。这似乎是由getView列表适配器中的未处理异常引起的。

于 2013-08-16T14:02:40.907 回答
0

在代码中操作视图时，检查可能有无效类型转换的地方。我对这条线有完全相同的错误

picture.setLayoutParams(new ViewGroup.LayoutParams(50, 50));

Choreographer 抛出此错误“android.view.ViewGroup$LayoutParams cannot be cast to android.widget.LinearLayout$LayoutParams”

将其更改为

picture.setLayoutParams(new android.widget.LinearLayout.LayoutParams(50, 50));

解决问题。

于 2013-07-27T22:30:25.080 回答