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.

Java SE 15 (Sept 2020) introduces sealed classes as a preview feature.Sealing allows classes and interfaces to have more control over their permitted subtypes; this is useful both for general ...

Last but not least, you get to learn all about inner classes and their classifications within Java. Inner classes are used to logically group classes and interfaces in one place so that your code ...

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 // ...

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 ...

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 ...

Developers can use familiar Java classes and interfaces to interact with the database, making it straightforward to perform database operations such as creating tables, inserting data, querying ...

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.