Quiz yourself: Initializing enums in Java code

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

Quiz yourself: Determining eligibility for garbage collection in Java

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

Quiz yourself: The correct syntax of Java lambda parameters

Be sure to know the difference between identifiers and specifiers.

Quiz yourself: Working with the Java Path class and the file system

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

Quiz yourself: Handling overloaded Java methods with arguments and return values

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

Quiz yourself: Using the SecurityManager class in Java

Be sure to use the checkPermission and doPrivileged methods correctly.

Quiz yourself: Working with abstract classes and default methods in Java

What happens when a default method is hidden and inaccessible?

Quiz yourself: Using subclasses and covariant return types

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

Quiz yourself: Manipulating Java lists—and views of lists

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

Quiz yourself: Performing reductions with Java streams using collectors and grouping

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

Quiz yourself: Use Java streams to filter, transform, and process data

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

Quiz yourself: Understanding valid annotation declarations

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

Quiz yourself: Use primitives such as the % operator

Test your knowledge of Java’s primitive operators.

Quiz yourself: Security threats and malicious code modifications

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

Quiz yourself: Say “hello” to the 1Z0-819 Java SE 11 certification exam

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

Quiz yourself: Correctly apply the static keyword to methods and fields

Test your knowledge of static fields in Java.

Quiz yourself: Create and extend abstract classes

Test your knowledge of abstract classes and their methods.

Quiz yourself: Read and write objects by using serialization

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

Quiz yourself: Apply encapsulation principles to a class

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

Quiz yourself: Use the Files class to copy or move files and directories

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