Question

以下是错误：

我什么时候得到的。我尝试在void android.widget.ListView.setAdapter(android.widget.ListAdapter)对象引用上调用虚拟方法null

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.kerempc.odev, PID: 8573
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.kerempc.odev/com.example.kerempc.odev.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ListView.setAdapter(android.widget.ListAdapter)' on a null object reference
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2778)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2856)
        at android.app.ActivityThread.-wrap11(Unknown Source:0)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1589)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:164)
        at android.app.ActivityThread.main(ActivityThread.java:6494)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ListView.setAdapter(android.widget.ListAdapter)' on a null object reference
        at com.example.kerempc.odev.MainFragment.onCreateView(MainFragment.java:25)
        at android.support.v4.app.Fragment.performCreateView(Fragment.java:2439)
        at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1460)
        at android.support.v4.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManager.java:1784)
        at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1852)
        at android.support.v4.app.BackStackRecord.executeOps(BackStackRecord.java:802)
        at android.support.v4.app.FragmentManagerImpl.executeOps(FragmentManager.java:2625)
        at android.support.v4.app.FragmentManagerImpl.executeOpsTogether(FragmentManager.java:2411)
        at android.support.v4.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManager.java:2366)
        at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:2273)
        at android.support.v4.app.FragmentManagerImpl.dispatchStateChange(FragmentManager.java:3273)
        at android.support.v4.app.FragmentManagerImpl.dispatchActivityCreated(FragmentManager.java:3229)
        at android.support.v4.app.FragmentController.dispatchActivityCreated(FragmentController.java:201)
        at android.support.v4.app.FragmentActivity.onStart(FragmentActivity.java:620)
        at android.support.v7.app.AppCompatActivity.onStart(AppCompatActivity.java:178)
        at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1334)
        at android.app.Activity.performStart(Activity.java:7029)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2741)

我该怎么办？

Answer 1

我建议您的ListAdapter对象（在代码中的某处）未正确实例化。当您尝试将ListAdapter传递给setAdapter()方法时可以看到NullPointerException为空，这就是为什么得到line 1, in <module> import pygame ModuleNotFoundError: No module named 'pygame'的原因。

发布包含适配器及其周围方法的代码会很好，因此我们可以提供更有意义的答案来解决您的问题。

运行Java代码时出现“程序已停止”的提示

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