java.lang.ClassNotFoundException(Api$ClientKey)

[cpq0329]

hei,I clone your project,but i doesn't run. can you help me? there are some tips:
Process: com.directions.sample, PID: 24051
java.lang.NoClassDefFoundError: Failed resolution of: Lcom/google/android/gms/common/api/Api$ClientKey;
at com.google.android.gms.location.places.Places.(Unknown Source)
at com.directions.sample.MainActivity.onCreate(MainActivity.java:82)
at android.app.Activity.performCreate(Activity.java:6910)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1123)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2746)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2864)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1567)
at android.os.Handler.dispatchMessage(Handler.java:105)
at android.os.Looper.loop(Looper.java:156)
at android.app.ActivityThread.main(ActivityThread.java:6523)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:941)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:831)
Caused by: java.lang.ClassNotFoundException: Didn't find class "com.google.android.gms.common.api.Api$ClientKey" on path: DexPathList[[zip file "/data/app/com.directions.sample-2/base.apk"],nativeLibraryDirectories=[/data/app/com.directions.sample-2/lib/arm64, /system/lib64, /vendor/lib64, /system/vendor/lib64, /product/lib64]]
at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56)
at java.lang.ClassLoader.loadClass(ClassLoader.java:380)
at java.lang.ClassLoader.loadClass(ClassLoader.java:312)
at com.google.android.gms.location.places.Places.(Unknown Source) 
at com.directions.sample.MainActivity.onCreate(MainActivity.java:82) 
at android.app.Activity.performCreate(Activity.java:6910) 
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1123) 
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2746) 
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2864) 
at android.app.ActivityThread.-wrap12(ActivityThread.java) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1567) 
at android.os.Handler.dispatchMessage(Handler.java:105) 
at android.os.Looper.loop(Looper.java:156) 
at android.app.ActivityThread.main(ActivityThread.java:6523) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:941) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:831) 
05-15 17:52:06.538 620-877/? E/logserver: imonitor_add_dynamic_path, path:/data/system/dropbox/[email protected]