The consumer interface can be confusing, even for advanced coders.
Predicate interfaces can be complicated, so be careful when working out the results.
Can a lambda return a lambda?
Define and implement functional interfaces that work as expected.
The subtleties of using var in lambda expressions
Using var with two-dimensional arrays requires careful attention.
The subtleties of using enums in a switch statement
The effects of declaring a class final
What fields can you access from default methods in interfaces?
When two object references point to the same StringBuilder instance, how are changes propagated?
Nuances of variable scope in for-loops
Java’s mechanisms and syntax for defining classes inside other classes
The subtleties of string concatenation
The scope rules of Java variables and an examination of shadowing
The subtleties of using a constructor to create an array
When exactly do you need to declare an exception?
For happy users, specify the locale correctly.
The subtleties of boxing and unboxing in streams
Where care is needed to get the results you expect from the Collectors class