android应用程序停止工作，查找错误

之前我的应用程序写得很好，但在做了一些编辑后它停止了工作。下面是我的应用程序停止工作的日志。请帮助：

    08-05 14:39:10.071: E/AndroidRuntime(767): FATAL EXCEPTION: main
    08-05 14:39:10.071: E/AndroidRuntime(767): java.lang.RuntimeException: Unable to       start activity ComponentInfo{com.example.hi_5physics/com.example.hi_5physics.MainActivity}: java.lang.NullPointerException
    08-05 14:39:10.071: E/AndroidRuntime(767):  at   android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
    08-05 14:39:10.071: E/AndroidRuntime(767):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
    08-05 14:39:10.071: E/AndroidRuntime(767):  at android.app.ActivityThread.access$600(ActivityThread.java:141)
    08-05 14:39:10.071: E/AndroidRuntime(767):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
    08-05 14:39:10.071: E/AndroidRuntime(767):  at android.os.Handler.dispatchMessage(Handler.java:99)
    08-05 14:39:10.071: E/AndroidRuntime(767):  at android.os.Looper.loop(Looper.java:137)
    08-05 14:39:10.071: E/AndroidRuntime(767):  at android.app.ActivityThread.main(ActivityThread.java:5039)
   08-05 14:39:10.071: E/AndroidRuntime(767):   at java.lang.reflect.Method.invokeNative(Native Method)
    08-05 14:39:10.071: E/AndroidRuntime(767):  at java.lang.reflect.Method.invoke(Method.java:511)
    08-05 14:39:10.071: E/AndroidRuntime(767):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
    08-05 14:39:10.071: E/AndroidRuntime(767):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
    08-05 14:39:10.071: E/AndroidRuntime(767):  at dalvik.system.NativeStart.main(Native Method)
    08-05 14:39:10.071: E/AndroidRuntime(767): Caused by: java.lang.NullPointerException
    08-05 14:39:10.071: E/AndroidRuntime(767):  at com.example.hi_5physics.MainActivity.onCreate(MainActivity.java:48)
    08-05 14:39:10.071: E/AndroidRuntime(767):  at android.app.Activity.performCreate(Activity.java:5104)
    08-05 14:39:10.071: E/AndroidRuntime(767):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
    08-05 14:39:10.071: E/AndroidRuntime(767):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
    08-05 14:39:10.071: E/AndroidRuntime(767):  ... 11 more
    08-05 14:39:16.201: I/Process(767): Sending signal. PID: 767 SIG: 9

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检查活动的

一旦创建

方法，它就是

NullPointerException

java.lang.RuntimeException:无法启动活动组件信息{com.example.hi_5physics/com.example.hi_5physics.MainActivity}:java.lang.NullPointerException

您的代码在哪里？

MainActivity.java

第48行中有什么内容？是的，一个nullPointerException，调试它们总是很有趣（我非常讨厌它们）

08-05 14:39:10.071: E/AndroidRuntime(767): Caused by: java.lang.NullPointerException
08-05 14:39:10.071: E/AndroidRuntime(767): at com.example.hi_5physics.MainActivity.onCreate(MainActivity.java:48)