用的离线android sdk里的例子,编译正确但是运行报错找不到类

错误如下,请教这是什么原因?

E/AndroidRuntime(10765): FATAL EXCEPTION: main

E/AndroidRuntime(10765): Process: com.baidu.tts.sample, PID: 10765

E/AndroidRuntime(10765): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.baidu.tts.sample/com.baidu.tts.sample.MainActivity}: java.lang.ClassNotFoundException: Didn't find class "com.baidu.tts.sample.MainActivity" on path: DexPathList[[zip file "/data/app/com.baidu.tts.sample-1/base.apk"],nativeLibraryDirectories=[/data/app/com.baidu.tts.sample-1/lib/arm64, /vendor/lib64, /system/lib64]]

E/AndroidRuntime(10765): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2439)

E/AndroidRuntime(10765): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2608)

E/AndroidRuntime(10765): at android.app.ActivityThread.access$800(ActivityThread.java:178)

E/AndroidRuntime(10765): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1470)

E/AndroidRuntime(10765): at android.os.Handler.dispatchMessage(Handler.java:111)

E/AndroidRuntime(10765): at android.os.Looper.loop(Looper.java:194)

E/AndroidRuntime(10765): at android.app.ActivityThread.main(ActivityThread.java:5637)

E/AndroidRuntime(10765): at java.lang.reflect.Method.invoke(Native Method)

E/AndroidRuntime(10765): at java.lang.reflect.Method.invoke(Method.java:372)

E/AndroidRuntime(10765): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:959)

E/AndroidRuntime(10765): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:754)

E/AndroidRuntime(10765): Caused by: java.lang.ClassNotFoundException: Didn't find class "com.baidu.tts.sample.MainActivity" on path: DexPathList[[zip file "/data/app/com.baidu.tts.sample-1/base.apk"],nativeLibraryDirectories=[/data/app/com.baidu.tts.sample-1/lib/arm64, /vendor/lib64, /system/lib64]]

E/AndroidRuntime(10765): at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56)

E/AndroidRuntime(10765): at java.lang.ClassLoader.loadClass(ClassLoader.java:511)

E/AndroidRuntime(10765): at java.lang.ClassLoader.loadClass(ClassLoader.java:469)

E/AndroidRuntime(10765): at android.app.Instrumentation.newActivity(Instrumentation.java:1071)

E/AndroidRuntime(10765): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)

E/AndroidRuntime(10765): ... 10 more

E/AndroidRuntime(10765): Suppressed: java.lang.NoClassDefFoundError: com.baidu.tts.sample.MainActivity

E/AndroidRuntime(10765): at dalvik.system.DexFile.defineClassNative(Native Method)

E/AndroidRuntime(10765): at dalvik.system.DexFile.defineClass(DexFile.java:226)

E/AndroidRuntime(10765): at dalvik.system.DexFile.loadClassBinaryName(DexFile.java:219)

E/AndroidRuntime(10765): at dalvik.system.DexPathList.findClass(DexPathList.java:321)

E/AndroidRuntime(10765): at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:54)

E/AndroidRuntime(10765): ... 14 more

E/AndroidRuntime(10765): Suppressed: java.lang.ClassNotFoundException: com.baidu.tts.sample.MainActivity

E/AndroidRuntime(10765): at java.lang.Class.classForName(Native Method)

E/AndroidRuntime(10765): at java.lang.BootClassLoader.findClass(ClassLoader.java:781)

E/AndroidRuntime(10765): at java.lang.BootClassLoader.loadClass(ClassLoader.java:841)

E/AndroidRuntime(10765): at java.lang.ClassLoader.loadClass(ClassLoader.java:504)

E/AndroidRuntime(10765): ... 13 more

E/AndroidRuntime(10765): Caused by: java.lang.NoClassDefFoundError: Class not found using the boot class loader; no stack available