User-defined classes in Java

Runtime class in Java. Every Java application has a single instance of class Runtime that allows the application to interface with the environment in which the application is running. The current runtime can be obtained from the getRuntime method.

In Java, all classes (built-in or user-defined) are (implicitly) subclasses of Object . Using an array of Object in the List class allows any kind of Object (an instance of any class) to be stored in the list. However, primitive types (int, char, etc) cannot be stored in the list.

In Java, all classes (built-in or user-defined) are (implicitly) subclasses of Object . Using an array of Object in the List class allows any kind of Object (an instance of any class) to be stored in the list. However, primitive types (int, char, etc) cannot be stored in the list.

In the above example, we have used three predefined methods main(), print(), and max(). We have used these methods directly without declaration because they are predefined. The print() method is a method of PrintStream class that prints the result on the console.

There are seven types of classes in Java: Static Class. Final Class. Abstract Class.

There are seven types of classes in Java: Static Class. Final Class. Abstract Class.

Predefined Method: In Java, predefined methods are the method that is already defined in the Java class libraries is known as predefined methods. It is also known as the standard library method or built-in method. We can directly use these methods just by calling them in the program at any point.