Notes – Introduction to Java

What is Java?

Java is a high-level, object-oriented programming language developed by Sun Microsystems in 1995. It is designed to be platform-independent, meaning code written in Java can run on any system that has a Java Virtual Machine (JVM).


Key Features of Java

  • Platform Independence – Java follows the “Write Once, Run Anywhere” (WORA) principle. Programs compiled in Java can run on any operating system with a JVM.
  • Object-Oriented – Java is built around classes and objects, making code reusable and modular.
  • Robust and Secure – Java provides strong memory management and security features like bytecode verification and exception handling.
  • Multi-threading – Java allows execution of multiple tasks simultaneously, improving efficiency.
  • Automatic Memory Management – Java handles memory allocation and deallocation using Garbage Collection (GC), reducing manual effort.

Why Learn Java?

  • Widely Used – Java is used in web applications, mobile apps, enterprise solutions, and even in AI and big data.
  • Beginner-Friendly – Java has a simple and readable syntax, making it great for beginners.
  • Strong Community Support – Millions of developers worldwide contribute to Java, providing libraries, frameworks, and solutions.
  • Job Opportunities – Java is a core requirement in many tech job roles, including Java Developer, Full Stack Developer, and Android Developer.

Java vs. Other Programming Languages

FeatureJavaC++Python
Platform IndependenceYes (JVM-based)NoYes (Interpreter-based)
Object-OrientedFullyPartiallyFully
Memory ManagementAutomatic (Garbage Collection)ManualAutomatic
Syntax ComplexityModerateComplexEasy
PerformanceHighVery HighModerate

How Java Works?

  1. Write Code – Java code is written in .java files.
  2. Compile Code – The Java Compiler (javac) converts code into bytecode (.class file).
  3. Execute Code – The Java Virtual Machine (JVM) reads the bytecode and runs the program.

This process ensures that Java programs can run on different platforms without modification.

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