There are rules about initializing enums. You need to know them.

You never can tell when the Java garbage collector will pick up the trash.

Be sure to know the difference between identifiers and specifiers.

Sometimes a slash is not a slash, as this quiz explains.

Do you know how the compiler selects which method to invoke when it’s forced to choose due to overloading?

Be sure to use the checkPermission and doPrivileged methods correctly.

What happens when a default method is hidden and inaccessible?

When overloading a Java method, be careful to specify the appropriate return types.

Is a list unmodifiable? Is it immutable? What about the views of the list?

The trick is to visualize how stream elements travel along the pipeline.

The average, sum, and count methods are trickier than they might seem.

Explore the allowed method return types to see where the code succeeds… or fails.

Test your knowledge of Java’s primitive operators.

Here’s what happens when good code meets bad people.

You now need only pass a single exam to become a certified Java SE 11 Developer.

Test your knowledge of static fields in Java.

Test your knowledge of abstract classes and their methods.

Test your knowledge of the java.io.Serializable interface.

Test your knowledge of a key object-oriented programming concept.

Test your knowledge of the java.nio.file.Files class.