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Introduction to Java Programming Language

Jul 19, 2024

Lecture 3: Introduction to Java Programming Language

Welcome and Motivation

  • Congratulations on making it to Lecture 3!
  • Stay motivated as learning new programming languages can be challenging.
  • Objective: We haven't written our first program yet, and still won't today.

Today’s Agenda

  • Learn about Java programming language.
  • Understand its origin, purpose, and key components.

What is Java?

  • A way to communicate with the computer using a programming language.
  • Java is an object-oriented programming language.

History of Java

  • Originated in 1991 by James Gosling and his team at Sun Microsystems.
  • Initially called Green Talk; later changed to Java in 1995.
  • Named Java because the team drank a lot of coffee from Java coffee beans (Island in Indonesia).

Basic Concepts

  • Java Development Kit (JDK)

    • Includes development tools like compilers.
    • Facilitates writing source files and compiling them to machine code.

  • Java Runtime Environment (JRE)

    • Provides necessary libraries and components to run Java applications.
    • Includes Java Virtual Machine (JVM) which runs Java programs.

  • Memory Management

    • How Java manages memory allocation and garbage collection.

Java Development Kit (JDK)

  • Contains tools for developing and running Java programs.
  • Main tools: Compiler (javac).
  • 2 main boxes inside JDK:
    1. Development tools: Compiler, debugger, etc.
    2. JVM and Libraries: For running compiled Java code.

Java Runtime Environment (JRE)

  • JVM and supporting files for execution.
  • Converts bytecode (from javac) to machine code the OS understands.
  • Includes libraries, runtime libraries and core classes.

Java Virtual Machine (JVM)

  • Components
    • Class Loader: Loads class files for execution.
    • Bytecode Verifier: Ensures code is safe and valid.
    • Just-In-Time (JIT) Compiler: Converts bytecode to machine code dynamically during execution.

Code Compilation Process

  1. Writing Code: Write code in Java and save as .java file.
  2. Compilation: Use javac (Java Compiler) to compile .java file to bytecode (.class file).
  3. Execution: JVM takes .class file, performs verification, and converts bytecode to machine code using JIT compiler.

Platform Independence of Java

  • Bytecode: Platform-independent intermediate representation of compiled Java code.
  • JVM: Platform-dependent, translates bytecode to machine code specific to the OS.

Summary

  • Java's history: From Green Talk to Java.
  • Components in JDK and JRE.
  • Role of JVM in executing Java code.
  • Compilation and execution process making Java platform-independent.

Next Steps

  • Understand how Java manages memory and garbage collection.
  • Write your first Java program in the next lecture.

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Full transcript