android studio compiled tips Gradle: error: package XXX does not exist

Gradle android studio inheritance

In the android studio 0.3.0 environment, there is a project, obviously there:
package com.umeng.common.b;
public class g
{
...
}

1, and the other to inherit it
package com.umeng.analytics;
class b implements com.umeng.common.b.g
{
...
}
Compile Tip Gradle: error: package does not exist
com.umeng.common.b
2, instead
package com.umeng.analytics;
import com.umeng.common.b.g;
class b implements g
{
...
}
Compile Tip Gradle: error: package does not exist
com.umeng.common.b<-! Main posts under Banner (D4) -><-! Posts under the main text (D5) ->