没有什么是空的，但我仍然得到一个空指针异常答案

【问题标题】：Nothing is null but I am still getting a null pointer exception没有什么是空的，但我仍然得到一个空指针异常
【发布时间】：2014-05-20 21:37:19
【问题描述】：

在我的片段内，convertView 为空，所以我将它设置为一个新视图。然后我打印出所有将要发送到 super.getView() 的内容，以查看其中任何内容是否为空。但我仍然得到一个空指针异常

view = super.getView(position, convertView, parent);

代码：

    listView.setAdapter(new ArrayAdapter<String>(getActivity(), android.R.layout.simple_list_item_1, R.id.textView1, list.items)
            {
                @Override
                public View getView(final int position, View convertView, ViewGroup parent)
                {
                    View view;
                    if (convertView == null)
                    {
                        System.err.println("convertView was null... updating");
                        LayoutInflater infl = getActivity().getLayoutInflater();
                        convertView = infl.inflate(android.R.layout.simple_list_item_1, parent, false);
                    }
                    System.out.println(position + "\n" + convertView + "\n" + parent);
                    view = super.getView(position, convertView, parent);
                    String entry = list.items.get(position);
                    TextView text1 = (TextView) view.findViewById(R.id.textView1);
                    text1.setText(entry);
                    return view;
                }
            });
    return view;

position、convertView、parent的值：

05-20 16:32:57.760: I/System.out(18373): 0
05-20 16:32:57.760: I/System.out(18373): android.widget.TextView{42caa628 V.ED....     ......I. 0,0-0,0 #1020014 android:id/text1}
05-20 16:32:57.760: I/System.out(18373): android.widget.ListView{42c32a68 VFED.VC. ......ID 0,88-1080,1442 #7f080004 app:id/list}

有什么我可以更改来修复/改进的吗？提前致谢。

将根据请求提供其他代码和信息。

完整的日志：

05-20 16:45:26.360: D/dalvikvm(22735): Late-enabling CheckJNI
05-20 16:45:26.580: D/dalvikvm(22735): JIT code cache reset in 0 ms (0 bytes 7/0)
05-20 16:45:26.580: D/dalvikvm(22735): GC_FOR_ALLOC freed 451K, 3% free 22716K/23216K, paused 27ms, total 27ms
05-20 16:45:26.650: D/dalvikvm(22735): JIT code cache reset in 0 ms (0 bytes 8/0)
05-20 16:45:26.650: D/dalvikvm(22735): GC_FOR_ALLOC freed 496K, 3% free 22727K/23276K, paused 24ms, total 24ms
05-20 16:45:26.710: D/dalvikvm(22735): GC_FOR_ALLOC freed 512K, 3% free 22728K/23288K, paused 20ms, total 20ms
05-20 16:45:26.760: D/dalvikvm(22735): GC_FOR_ALLOC freed 501K, 3% free 22737K/23288K, paused 19ms, total 19ms
05-20 16:45:26.760: I/System.out(22735): FamilyLists
05-20 16:45:26.790: D/dalvikvm(22735): GC_FOR_ALLOC freed 71K, 3% free 22769K/23288K, paused 21ms, total 21ms
05-20 16:45:26.820: D/dalvikvm(22735): GC_FOR_ALLOC freed <1K, 3% free 22790K/23288K, paused 24ms, total 24ms
05-20 16:45:26.820: I/dalvikvm-heap(22735): Grow heap (frag case) to 22.380MB for 82960-byte allocation
05-20 16:45:26.840: D/dalvikvm(22735): GC_FOR_ALLOC freed <1K, 3% free 22871K/23372K, paused 21ms, total 21ms
05-20 16:45:26.870: D/dalvikvm(22735): GC_FOR_ALLOC freed 43K, 3% free 22895K/23372K, paused 18ms, total 18ms
05-20 16:45:26.910: D/dalvikvm(22735): GC_FOR_ALLOC freed 107K, 3% free 22936K/23456K, paused 20ms, total 20ms
05-20 16:45:26.950: I/Adreno-EGL(22735): <qeglDrvAPI_eglInitialize:320>: EGL 1.4 QUALCOMM Build: I0404c4692afb8623f95c43aeb6d5e13ed4b30ddbDate: 11/06/13
05-20 16:45:26.970: D/OpenGLRenderer(22735): Enabling debug mode 0
05-20 16:45:26.980: W/System.err(22735): convertView was null... updating
05-20 16:45:26.980: I/System.out(22735): 0
05-20 16:45:26.980: I/System.out(22735): android.widget.TextView{42c9e3b8 V.ED.... ......I. 0,0-0,0 #1020014 android:id/text1}
05-20 16:45:26.980: I/System.out(22735): android.widget.ListView{42c4bbc8 VFED.VC. ......ID 0,88-1080,1442 #7f080004 app:id/list}
05-20 16:45:26.980: D/AndroidRuntime(22735): Shutting down VM
05-20 16:45:26.980: W/dalvikvm(22735): threadid=1: thread exiting with uncaught exception (group=0x41613ba8)
05-20 16:45:26.980: E/AndroidRuntime(22735): FATAL EXCEPTION: main
05-20 16:45:26.980: E/AndroidRuntime(22735): Process: com.mail929.android.familylists, PID: 22735
05-20 16:45:26.980: E/AndroidRuntime(22735): java.lang.NullPointerException
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:392)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.widget.ArrayAdapter.getView(ArrayAdapter.java:362)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at com.mail929.android.familylists.ListFragment$2.getView(ListFragment.java:59)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.widget.AbsListView.obtainView(AbsListView.java:2263)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.widget.ListView.makeAndAddView(ListView.java:1790)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.widget.ListView.fillDown(ListView.java:691)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.widget.ListView.fillFromTop(ListView.java:752)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.widget.ListView.layoutChildren(ListView.java:1630)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.widget.AbsListView.onLayout(AbsListView.java:2091)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.view.View.layout(View.java:14817)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.view.ViewGroup.layout(ViewGroup.java:4631)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.widget.RelativeLayout.onLayout(RelativeLayout.java:1055)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.view.View.layout(View.java:14817)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.view.ViewGroup.layout(ViewGroup.java:4631)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:453)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.widget.FrameLayout.onLayout(FrameLayout.java:388)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.view.View.layout(View.java:14817)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.view.ViewGroup.layout(ViewGroup.java:4631)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.support.v4.widget.DrawerLayout.onLayout(DrawerLayout.java:743)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.view.View.layout(View.java:14817)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.view.ViewGroup.layout(ViewGroup.java:4631)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:453)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.widget.FrameLayout.onLayout(FrameLayout.java:388)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.view.View.layout(View.java:14817)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.view.ViewGroup.layout(ViewGroup.java:4631)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at com.android.internal.widget.ActionBarOverlayLayout.onLayout(ActionBarOverlayLayout.java:374)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.view.View.layout(View.java:14817)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.view.ViewGroup.layout(ViewGroup.java:4631)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:453)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.widget.FrameLayout.onLayout(FrameLayout.java:388)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.view.View.layout(View.java:14817)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.view.ViewGroup.layout(ViewGroup.java:4631)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:1987)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1744)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1000)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5670)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.view.Choreographer$CallbackRecord.run(Choreographer.java:761)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.view.Choreographer.doCallbacks(Choreographer.java:574)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.view.Choreographer.doFrame(Choreographer.java:544)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:747)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.os.Handler.handleCallback(Handler.java:733)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.os.Handler.dispatchMessage(Handler.java:95)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.os.Looper.loop(Looper.java:136)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at android.app.ActivityThread.main(ActivityThread.java:5017)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at java.lang.reflect.Method.invokeNative(Native Method)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at java.lang.reflect.Method.invoke(Method.java:515)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at de.robv.android.xposed.XposedBridge.main(XposedBridge.java:132)
05-20 16:45:26.980: E/AndroidRuntime(22735):    at dalvik.system.NativeStart.main(Native Method)

【问题讨论】：

请发布堆栈跟踪。
你能发布你的 logcat 吗？
将null 参数传递给方法本身不会导致NullPointerException。你真的应该阅读What is a NullPointerException?
有些东西是空的。你考虑过“父母”吗？您应该在这个问题中包含堆栈跟踪。
不要像这样覆盖 ArrayAdapter 上的 getView()。要么使用 ArrayAdapter 的默认 getView() 实现，要么直接从 BaseAdapter 继承来实现你自己的适配器来封装你的集合。

标签： java android android-fragments android-listview android-arrayadapter

【解决方案1】：

您正在使用android.R.layout.simple_list_item_1，其中TextView 的ID 是android.R.id.text1，不是 R.id.textView1 source。

试试下面的代码，请理解Adapter的工作原理。 ListView 和自定义 Adapter 上的很多东西都可以在 Internet 上找到：

listView.setAdapter(new ArrayAdapter<String>(getActivity(), android.R.layout.simple_list_item_1, android.R.id.text1, list.items)
            {
                @Override
                public View getView(final int position, View convertView, ViewGroup parent)
                {
                    View view = super.getView(position, convertView, parent);
                    String entry = list.items.get(position);
                    TextView text1 = (TextView) view.findViewById(android.R.id.text1);
                    text1.setText(entry);
                    return view;
                }
            });

【讨论】：

谢谢，我完全忘记了它使用了android.R.id.text1。但不幸的是，这是我的主要问题的原因。
没关系，我忘了更改顶部的 R.id.textView1。谢谢。