11-25 13:20:55.263: D/AndroidRuntime(467): Shutting down VM
11-25 13:20:55.263: W/dalvikvm(467): threadid=1: thread exiting with uncaught exception (group=0x40015560)
11-25 13:20:55.313: E/AndroidRuntime(467): FATAL EXCEPTION: main
11-25 13:20:55.313: E/AndroidRuntime(467): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.xample.counter/com.xample.counter.MainActivity}: java.lang.NullPointerException
11-25 13:20:55.313: E/AndroidRuntime(467): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
11-25 13:20:55.313: E/AndroidRuntime(467): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
11-25 13:20:55.313: E/AndroidRuntime(467): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
11-25 13:20:55.313: E/AndroidRuntime(467): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
11-25 13:20:55.313: E/AndroidRuntime(467): at android.os.Handler.dispatchMessage(Handler.java:99)
11-25 13:20:55.313: E/AndroidRuntime(467): at android.os.Looper.loop(Looper.java:123)
11-25 13:20:55.313: E/AndroidRuntime(467): at android.app.ActivityThread.main(ActivityThread.java:3683)
11-25 13:20:55.313: E/AndroidRuntime(467): at java.lang.reflect.Method.invokeNative(Native Method)
11-25 13:20:55.313: E/AndroidRuntime(467): at java.lang.reflect.Method.invoke(Method.java:507)
11-25 13:20:55.313: E/AndroidRuntime(467): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
11-25 13:20:55.313: E/AndroidRuntime(467): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
11-25 13:20:55.313: E/AndroidRuntime(467): at dalvik.system.NativeStart.main(Native Method)
11-25 13:20:55.313: E/AndroidRuntime(467): Caused by: java.lang.NullPointerException
11-25 13:20:55.313: E/AndroidRuntime(467): at com.xample.counter.MainActivity.onCreate(MainActivity.java:28)
11-25 13:20:55.313: E/AndroidRuntime(467): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
11-25 13:20:55.313: E/AndroidRuntime(467): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
11-25 13:20:55.313: E/AndroidRuntime(467): ... 11 more
我是android新手,遇到此错误无法解决,请帮帮我