A Java program is typically structured in the following way:
-
Package Declaration (Optional):
- You can declare a package at the beginning of your Java file to organize your classes into logical groups.
-
Import Statements (Optional):
- You can import other Java classes or packages that you want to use in your program.
-
Class Declaration:
- Every Java program consists of at least one class.
- The class declaration is the basic structure of a Java program and contains the definition of the class.
-
Main Method:
- The main method is the entry point of a Java program.
- It has the following signature:
public static void main(String[] args)
. - The program execution starts from the main method.
-
Class Body:
- The class body contains the member variables (fields) and methods of the class.
-
Member Variables (Fields):
- Member variables are the variables declared within a class.
- They represent the state or data associated with the class.
-
Methods:
- Methods are functions defined within a class.
- They define the behavior of the class and perform various operations.
-
Statements and Expressions:
- Java programs consist of statements and expressions.
- Statements are individual program instructions, and expressions produce values.
Here’s an example illustrating the basic structure of a Java program:
package com.example; import java.util.*; public class MyClass { private int myVariable; public static void main(String[] args) { MyClass myObject = new MyClass(); myObject.myMethod(); } public void myMethod() { myVariable = 10; System.out.println("Value of myVariable: " + myVariable); } }
In the above example, we have a class called MyClass
with a member variable myVariable
, a main
method as the entry point of the program, and another method myMethod
that sets the value of myVariable
and prints it to the console.