ClassNotFoundException：无法运行应用

无法运行应用。该应用程序成功编译，但因该异常而崩溃

FATAL EXCEPTION: main
Process: com.example.myapplication, PID: 15209
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.myapplication/com.example.myapplication.MainActivity}: java.lang.ClassNotFoundException: Didn't find class "com.example.myapplication.MainActivity" on path: DexPathList[[zip file "/data/app/com.example.myapplication-2/base.apk"],nativeLibraryDirectories=[/vendor/lib, /system/lib]]
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2426)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2601)
    at android.app.ActivityThread.access$800(ActivityThread.java:178)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1470)
    at android.os.Handler.dispatchMessage(Handler.java:111)
    at android.os.Looper.loop(Looper.java:194)
    at android.app.ActivityThread.main(ActivityThread.java:5637)
    at java.lang.reflect.Method.invoke(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:372)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:960)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
    Caused by: java.lang.ClassNotFoundException: Didn't find class "com.example.myapplication.MainActivity" on path: DexPathList[[zip file "/data com.example.myapplication-2/base.apk"],nativeLibraryDirectories=[/vendor/lib, /system/lib]]
    at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:511)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:469)
    at android.app.Instrumentation.newActivity(Instrumentation.java:1071)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2601) 
    at android.app.ActivityThread.access$800(ActivityThread.java:178) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1470) 
    at android.os.Handler.dispatchMessage(Handler.java:111) 
    at android.os.Looper.loop(Looper.java:194) 
    at android.app.ActivityThread.main(ActivityThread.java:5637) 
    at java.lang.reflect.Method.invoke(Native Method) 
    at java.lang.reflect.Method.invoke(Method.java:372) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:960) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755) 
    Suppressed: java.lang.ClassNotFoundException: com.example.myapplication.MainActivity
    at java.lang.Class.classForName(Native Method)
    at java.lang.BootClassLoader.findClass(ClassLoader.java:781)
    at java.lang.BootClassLoader.loadClass(ClassLoader.java:841)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:504)
    ... 13 more
    Caused by: java.lang.NoClassDefFoundError: Class not found using the boot class loader; no stack available

这是我的第一次经历。我已经完成了几个项目，没有任何错误。我也尝试过重建和清理。我尝试了这些帖子，但没有用：

找不到类错误，但确实存在类

Android应用程式ClassNotFoundException主要活动