Java Development Kit

What is Java Development Kit (JDK)?

The core class type included in Java is called the JDK. It includes all the basic tools we would need in a modern application, including everything from collection types and queues, to web sockets, to files and image processing.

As an object-oriented language, methods and properties are organized into classes that are organized in packages. Each Java class should be defined in one file named for that class. The classes under java.lang, such as String, are always available. Otherwise, we would need to explicitly import the classes using an import statement at the top of our Java file. An instance of a class is called an object. All objects are passed by value. Unlike in C, we cannot modify a reference pointer.

A particular aspect of Java is that there are special types called primitives. Unlike objects, primitives do not have methods and always have a value. In other words, they can never be null.