In Java, a program consists of one or more classes, and each class contains methods. The main method is the entry point of the program, and it is the first method that is executed when the program runs.

A class in Java is a template for creating objects, and it defines the variables and methods that belong to the objects of that class. A class can contain data members (variables) and methods, and it can also have constructors and destructors.

Here is an example of a simple Java program that declares a class and a main method:

public class MyClass {
public static void main(String[] args) {
System.out.println("Hello World!");
}
}

In this example, the class is called MyClass, and the main method is the entry point of the program. When the program is executed, the main method will print “Hello World!” to the console.

Java is an object-oriented programming language, which means that it is based on the concept of objects. An object is a combination of data and behavior, and it represents a real-world entity or concept. Objects interact with each other through methods, and they can also inherit properties and behaviors from other objects.