Java Programming Introduction

Installation

• Java Development Kit (JDK):

  • Go to Google and search for "Java JDK download."
  • Download the latest version as Java core language doesn't change, just features are added.
  • Run the executable file to install.

• Integrated Development Environment (IDE):

  • Popular options: Eclipse, NetBeans, IntelliJ.
  • For the class, use Eclipse IDE.
  • Download and install the latest version.
  • Eclipse workspace: Place to store Java code.

Project Setup

• Create a new Java project in Eclipse:
  • File -> New -> Java project -> Name it (e.g., My First Java Project).
  • Uncheck "Create module-info.java".
  • Finish setup.

Online IDE

• Replit:
  • An alternative to installing JDK and IDE.
  • Start coding on Replit with a Gmail account.
  • Create Java projects and run them directly.

Java Basics

Java’s Popularity

• Platform Independent:
  • Uses Java Virtual Machine (JVM) to run on different OS.
  • Code runs on any OS with JVM support.

Basic Concepts

• Packages:

  • Folder structures for Java projects.

• Java Programs:

  • Use classes to organize code.
  • Create packages and classes for each session.

Writing Java Code

• Comments:

  • Multi-line: /* comment */
  • Single-line: // comment

• Printing to Console:

  • Syntax: System.out.println("text").

• Variables and Data Types:

  • Integers, Doubles, Strings.
  • Variables hold data like numbers and text.

• Operators:

  • Arithmetic (e.g., +, -, *, /).
  • Relational (e.g., ==, !=, <, >).
  • Logical (e.g., &&, ||).*

Control Structures

Conditional Statements

• If statement:

  • Syntax: if (condition) { // code }
  • Use else if and else for multiple conditions.

• Switch Case:

  • Syntax: switch(variable) { case value: // code; break; }
  • Supports int and String types.

Loops

• For Loop:

  • Syntax: for (initialization; condition; increment) { // code }

• While Loop:

  • Syntax: while (condition) { // code }

• Do-While Loop:

  • Syntax: do { // code } while (condition);

Advanced Topics

Arrays

• Single-dimensional Arrays:

  • Declaration: int[] array = {1, 2, 3};
  • Access elements via index.

• Two-dimensional Arrays:

  • Declaration: int[][] array = new int[rows][columns];
  • Represented as matrices.

String Manipulation

• Concatenation: Using + operator.
• Methods: .toUpperCase(), .substring(), .charAt().

Wrapper Classes

• Convert String to number using Integer.parseInt() or Double.parseDouble().

Object-Oriented Programming

Classes and Objects

• Class: Blueprint for objects, contains data and methods.
• Object: Instance of a class, has its own copy of data and methods.

Constructors

• Method with the same name as the class.
• Initializes objects, setting default values.
• Does not return any type, not even void.

Methods

• Can return values to the caller (main method).
• Can accept arguments to manipulate data.

Key Terminologies

• Data: Variables within a class.
• Methods: Functions defined inside a class.
• Constructor: Used to create objects with initialized values.

Additional Notes

Java Programming: Key Learning Points

• Always download the latest JDK and IDE.
• Use Replit for quick online coding.
• Understand core programming constructs: loops, conditionals, and data types.
• Practice object-oriented programming by creating and manipulating classes and objects.
• Use constructors for initializing objects with default values.