Introduction to Java

What Is Java?

Java is a general-purpose, object-oriented programming language created at Sun Microsystems by James Gosling and his team in 1995. It was designed with one central promise: a program written once should run anywhere, on any device that carries a Java Virtual Machine (JVM).

The syntax of Java was deliberately made familiar to C and C++ programmers, so developers who already knew those languages could move to Java quickly. But unlike C, Java hides the low-level details of memory management from the developer and handles many error conditions through a structured exception system.

Why Developers Choose Java

• Platform independent: compiled bytecode runs on any OS that provides a JVM.
• Object oriented: everything meaningful is modelled as objects with state and behaviour.
• Memory safe: the garbage collector reclaims unused objects automatically, and the runtime checks array bounds.
• Rich standard library: collections, networking, file handling and more ship with the JDK.
• Large ecosystem: Spring, Hibernate, Maven and thousands of libraries are built on Java.

A Tiny Taste of Java

public class Welcome {
    public static void main(String[] args) {
        System.out.println("Welcome to Core Java!");
        // the JVM starts executing from main
    }
}

Every Java application needs a class and a main method. When you run the program, the JVM finds this method and executes the statements inside it line by line.

Key Points

• Java compiles to bytecode which runs on the JVM.
• It is object oriented, platform independent and memory safe.
• Programs are organised into classes; every program needs a main method.