Nesting classes is one way to better organize your code. For example, say you have a non-nested class ... For example, the Matcher class, in java.util.regex, provides a results() ...

In the package directive’s absence, those classes and interfaces belong to the unnamed package (the directory the JVM regards as the current directory—the directory where a Java program begins ...

By allowing developers to define closed hierarchies, sealed classes improve code safety, clarity and maintainability. Sealed classes make Java an even more powerful and expressive language and set the ...