In this Java 101 tutorial, I’ve explained how interfaces differ from classes, and showed you how to declare, implement, and extend interfaces in your Java programs.

The release of Java SE 15 in Sept 2020 will introduce "sealed classes" (JEP 360) as a preview feature. A sealed class is a class or interface which restricts which other classes or interfaces may ...

Listing 3. Major classes and interfaces used in the framework. public interface SecurityDescriptor extends java.io.Serializable { // The getPermission methods return a constants defined in the // ...

Another type of class that wasn't in Java 11 but that you will find in Java 17 is sealed classes. Sealed classes and interfaces are designed to allow you to control which of the other classes are ...

JDBC interfaces, classes and components. The JDBC API is composed of a number of interfaces and classes that represent a connection to the database, provide facilities for sending SQL queries to a ...

For an introduction to Java interfaces, including the difference between classes and interfaces, see my Java 101 tutorial Working with interfaces in Java. Nesting interfaces in classes.