Java lets you declare interfaces inside of classes. Once declared, an interface is automatically a static member of the class. There is no need to declare the interface with the static keyword.

The functional Predicate interface gets used extensively by the Java 8 Streams API. Any developer who wants to master functional programming in Java will need to be comfortable with the Predicate ...

Java's interface language feature often puzzles newcomers to this language. Jeff eliminates this mystery by presenting the six roles that interfaces play in the Java language.