NullPointerException：null result when primitive expected

最新推荐文章于 2024-02-29 15:08:04 发布

原创最新推荐文章于 2024-02-29 15:08:04 发布 · 1.2k 阅读

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#android #异常

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本文分析了Android应用中出现的空指针异常的具体原因，该异常发生在AudioManager请求音频焦点时返回null，并探讨了解决方案，包括确保同步通信正常返回及改用异步通信方式。

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完整异常日志如下：

E/AndroidRuntime(  962): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.audiopolicytest/com.example.audiopolicytest.MainActivity}: java.lang.NullPointerException: null result when primitive expected
E/AndroidRuntime(  962):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2184)
E/AndroidRuntime(  962):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
E/AndroidRuntime(  962):    at android.app.ActivityThread.access$800(ActivityThread.java:135)
E/AndroidRuntime(  962):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
E/AndroidRuntime(  962):    at android.os.Handler.dispatchMessage(Handler.java:102)
E/AndroidRuntime(  962):    at android.os.Looper.loop(Looper.java:136)
E/AndroidRuntime(  962):    at android.app.ActivityThread.main(ActivityThread.java:5001)
E/AndroidRuntime(  962):    at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime(  962):    at java.lang.reflect.Method.invoke(Method.java:515)
E/AndroidRuntime(  962):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
E/AndroidRuntime(  962):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
E/AndroidRuntime(  962):    at com.alta.android.chiron.Chiron.main(Chiron.java:137)
E/AndroidRuntime(  962):    at dalvik.system.NativeStart.main(Native Method)
E/AndroidRuntime(  962): Caused by: java.lang.NullPointerException: null result when primitive expected
E/AndroidRuntime(  962):    at android.media.AudioManager.requestAudioFocus(Native Method)
E/AndroidRuntime(  962):    at com.example.audiopolicytest.MainActivity.onCreate(MainActivity.java:25)
E/AndroidRuntime(  962):    at android.app.Activity.performCreate(Activity.java:5231)
E/AndroidRuntime(  962):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
E/AndroidRuntime(  962):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2148)