适配器getView方法返回值为空的BUG

最新推荐文章于 2022-05-23 02:35:17 发布

MrZhangxi

最新推荐文章于 2022-05-23 02:35:17 发布

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分类专栏： Android 那些年那些错

本文链接：https://blog.youkuaiyun.com/y6622576/article/details/51862370

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在实现新闻客户端时遇到适配器问题，ListView加载数据时出现空指针异常。原因是自定义Adapter的getView方法创建View后忘记返回，导致错误。

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今天跟着视频做新闻客户端，在调用适配器给ListView添加数据时，一直在报空指针异常，如下

</pre><pre name="code" class="java">07-08 08:48:42.178: E/Trace(894): error opening trace file: No such file or directory (2)
07-08 08:48:42.999: I/Choreographer(894): Skipped 37 frames!  The application may be doing too much work on its main thread.
07-08 08:48:43.089: D/gralloc_goldfish(894): Emulator without GPU emulation detected.
07-08 08:48:43.438: I/Choreographer(894): Skipped 49 frames!  The application may be doing too much work on its main thread.
07-08 08:48:43.568: D/AndroidRuntime(894): Shutting down VM
07-08 08:48:43.568: W/dalvikvm(894): threadid=1: thread exiting with uncaught exception (group=0x40a122a0)
07-08 08:48:43.638: E/AndroidRuntime(894): FATAL EXCEPTION: main
07-08 08:48:43.638: E/AndroidRuntime(894): java.lang.NullPointerException
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.widget.AbsListView.obtainView(AbsListView.java:2273)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.widget.ListView.makeAndAddView(ListView.java:1769)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.widget.ListView.fillDown(ListView.java:672)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.widget.ListView.fillFromTop(ListView.java:733)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.widget.ListView.layoutChildren(ListView.java:1622)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.widget.AbsListView.onLayout(AbsListView.java:2106)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.view.View.layout(View.java:13754)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.view.ViewGroup.layout(ViewGroup.java:4364)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1649)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1507)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.widget.LinearLayout.onLayout(LinearLayout.java:1420)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.view.View.layout(View.java:13754)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.view.ViewGroup.layout(ViewGroup.java:4364)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.widget.FrameLayout.onLayout(FrameLayout.java:448)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.view.View.layout(View.java:13754)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.view.ViewGroup.layout(ViewGroup.java:4364)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1649)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1507)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.widget.LinearLayout.onLayout(LinearLayout.java:1420)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.view.View.layout(View.java:13754)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.view.ViewGroup.layout(ViewGroup.java:4364)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.widget.FrameLayout.onLayout(FrameLayout.java:448)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.view.View.layout(View.java:13754)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.view.ViewGroup.layout(ViewGroup.java:4364)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:1868)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1689)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1000)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4214)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.view.Choreographer$CallbackRecord.run(Choreographer.java:725)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.view.Choreographer.doCallbacks(Choreographer.java:555)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.view.Choreographer.doFrame(Choreographer.java:525)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:711)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.os.Handler.handleCallback(Handler.java:615)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.os.Handler.dispatchMessage(Handler.java:92)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.os.Looper.loop(Looper.java:137)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at android.app.ActivityThread.main(ActivityThread.java:4745)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at java.lang.reflect.Method.invokeNative(Native Method)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at java.lang.reflect.Method.invoke(Method.java:511)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
07-08 08:48:43.638: E/AndroidRuntime(894): 	at dalvik.system.NativeStart.main(Native Method)

错误中提示要将耗时操作放到子线程中，这个容易误导。

仔细检查了代码，发现是自定义Adapter的getView方法创建View对象以后没有返回造成的错误