问在android中删除java文件后的NoClassFoundError

EN

E/AndroidRuntime(23686): FATAL EXCEPTION: main
E/AndroidRuntime(23686): Process: com.esouqatar.customer, PID: 23686
E/AndroidRuntime(23686): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.esouqatar.customer/com.esouqatar.customer.ProductList_Activity}: java.lang.ClassNotFoundException: Didn't find class "com.esouqatar.customer.ProductList_Activity" on path: DexPathList[[zip file "/data/app/com.esouqatar.customer-2/base.apk"],nativeLibraryDirectories=[/vendor/lib, /system/lib]]
E/AndroidRuntime(23686):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2256)
E/AndroidRuntime(23686):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2405)
E/AndroidRuntime(23686):    at android.app.ActivityThread.access$800(ActivityThread.java:149)
E/AndroidRuntime(23686):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1324)
E/AndroidRuntime(23686):    at android.os.Handler.dispatchMessage(Handler.java:102)
E/AndroidRuntime(23686):    at android.os.Looper.loop(Looper.java:211)
E/AndroidRuntime(23686):    at android.app.ActivityThread.main(ActivityThread.java:5315)
E/AndroidRuntime(23686):    at java.lang.reflect.Method.invoke(Native Method)
E/AndroidRuntime(23686):    at java.lang.reflect.Method.invoke(Method.java:372)
E/AndroidRuntime(23686):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:941)             
E/AndroidRuntime(23686):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:736)   
E/AndroidRuntime(23686): Caused by: java.lang.ClassNotFoundException: Didn't find class "com.esouqatar.customer.ProductList_Activity" on path: DexPathList[[zip file "/data/app/com.esouqatar.customer-2/base.apk"],nativeLibraryDirectories=[/vendor/lib, /system/lib]]
E/AndroidRuntime(23686):    at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56)
E/AndroidRuntime(23686):    at java.lang.ClassLoader.loadClass(ClassLoader.java:511)
E/AndroidRuntime(23686):    at java.lang.ClassLoader.loadClass(ClassLoader.java:469)
E/AndroidRuntime(23686):    at android.app.Instrumentation.newActivity(Instrumentation.java:1065)
E/AndroidRuntime(23686):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2246)
E/AndroidRuntime(23686):    ... 10 more
E/AndroidRuntime(23686):    Suppressed: java.lang.ClassNotFoundException: com.esouqatar.customer.ProductList_Activity
E/AndroidRuntime(23686):        at java.lang.Class.classForName(Native Method)
E/AndroidRuntime(23686):        at java.lang.BootClassLoader.findClass(ClassLoader.java:781)
E/AndroidRuntime(23686):        at java.lang.BootClassLoader.loadClass(ClassLoader.java:841)
E/AndroidRuntime(23686):        at java.lang.ClassLoader.loadClass(ClassLoader.java:504)
E/AndroidRuntime(23686):        ... 13 more
E/AndroidRuntime(23686):    Caused by: java.lang.NoClassDefFoundError: Class not found using the boot class loader; no stack available