java.lang.NoSuchFieldError: pid

加载.apatch后，报这个错误，什么问题？
java.lang.NoSuchFieldError: pid
at com.gw.andfix.MainActivity.onCreate(MainActivity.java)
at android.app.Activity.performCreate(Activity.java:5310)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1088)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2381)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2469)
at android.app.ActivityThread.access$1100(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1362)
at android.os.Handler.dispatchMessage(Handler.java:110)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:5551)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:914)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:730)
at dalvik.system.NativeStart.main(Native Method)

Start at com.gw.andfix.MainActivity.onCreate and reproduce the failure after loading the .apatch file, using the supplied NoSuchFieldError: pid stack trace as the entry point. Trace where the pid field is expected and determine what condition causes it to be unavailable; done means the failure is explained and the compatible patch or usage path is identified.

Written by the indexing model from the issue text.