NullPointerException：null result when primitive expected

来源：互联网发布：centos 7服务器dvd安装编辑：程序博客网时间：2024/06/01 09:27

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 expectedE/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 expectedE/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)

【问题原因】：该异常翻译过来就是：返回结果为null与实际期望的返回类型不一致。此处导致该错误的原因是由于跨进程同步通信时，远程进程无法连接导致该错误。
【解决方法】：方法一是保证同步通信正常返回；方法二是改同步通信为异步通信，使调用迅速返回。

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