log4j:ERROR A "org.apache.log4j.ConsoleAppender" object is not assignable to a "org.apache.log4j.Appender" variable

Question

I am making a web app using gradle. I used log4j in this app. When I build the project I am getting error...

• log4j:ERROR A "org.apache.log4j.ConsoleAppender" object is not assignable to a "org.apache.log4j.Appender" variable.
• log4j:ERROR The class "org.apache.log4j.Appender" was loaded by
• log4j:ERROR [org.powermock.core.classloader.MockClassLoader@16a40b2] whereas object of type
• log4j:ERROR "org.apache.log4j.ConsoleAppender" was loaded by [sun.misc.Launcher$AppClassLoader@5e3a78ad].
• log4j:ERROR Could not instantiate appender named "stdout".

I still did not find a good answer. And I forgot to say, My project build correctly and show log massages correctly. It doesn't work only on test classes.

Answer 1

Adding this annotation works for me.

@PowerMockIgnore("org.apache.log4j.*") 

Answer 2

Your classpath contains 2 copies of log4j library. Exclude one and try again.

Answer 3

There is a Clear answer here. :D

When we have a final method and slf4j loggers in our classes. We have to use powermock in our test class. Because of this we have to use @MockPolicy(Slf4jMockPolicy.class) with particuler imports at the test class which we used Powermock.