Question

嘿伙计们我试图创建一个在MainActivity中创建一些数据的应用程序，然后将其存储到一个数组并将其传递给另一个活动，我创建了另一个活动（其中包含一个ListView），以便用户可以查看数据，但每当我在第二个活动的java文件中引用ListView时，Intent就会停止工作并且应用程序停止响应。以下是我在应用中找到的导致错误的代码：

ListView codeList = (ListView) findViewById(R.id.code_list);

ArrayAdapter adapter = new ArrayAdapter<String>(this, android.R.layout.simple_expandable_list_item_1, code_array);

codeList.setAdapter(adapter);

这是图像：

http://imgur.com/FDFJVrg

这些是我在logcat中获得的错误日志代码：

09-07 10:18:10.191  12852-12852/com.plufinity.steven.codey E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.plufinity.steven.codey, PID: 12852
java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.Object.toString()' on a null object reference
        at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:394)
        at android.widget.ArrayAdapter.getView(ArrayAdapter.java:362)
        at android.widget.AbsListView.obtainView(AbsListView.java:2255)
        at android.widget.ListView.measureHeightOfChildren(ListView.java:1263)
        at android.widget.ListView.onMeasure(ListView.java:1175)
        at android.view.View.measure(View.java:16521)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
        at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
        at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
        at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
        at android.view.View.measure(View.java:16521)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
        at android.view.View.measure(View.java:16521)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
        at com.android.internal.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:327)
        at android.view.View.measure(View.java:16521)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
        at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2552)
        at android.view.View.measure(View.java:16521)
        at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1912)
        at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1109)
        at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1291)
        at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:996)
        at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5600)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:761)
        at android.view.Choreographer.doCallbacks(Choreographer.java:574)
        at android.view.Choreographer.doFrame(Choreographer.java:544)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:747)
        at android.os.Handler.handleCallback(Handler.java:733)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:136)
        at android.app.ActivityThread.main(ActivityThread.java:5139)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:796)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:612)

Answer 1

当适配器尝试在传递给适配器的数组中的对象上调用ArrayAdapter.createViewFromResource()时，会出现toString()中的这样的NPE。确保数组中不包含任何null值。

引用ListView时的一些问题

1 个答案: