Java Course Notes

Jul 30, 2024

Java Course Notes

Instructor Introduction

  • Mosh will be the instructor.
  • Course contents include:
    • Installing necessary tools for Java.
    • Basics of Java programming.
    • Building algorithms and writing professional-quality code.
  • Designed for beginners.

Instructor Background

  • Mosh: Software engineer with 20 years of experience.
  • Over 3 million people taught to code.
  • Owns a coding school called "Code with Mosh."

Course Overview

Tools Installation

  1. Java Development Kit (JDK)

    • Search for "JDK download."
    • Accept license agreement and download the appropriate version for your OS (Windows, Mac, Linux).
    • Install JDK.
  2. Code Editor

    • Recommended: IntelliJ IDEA (Community edition)
    • Alternatives: NetBeans, Eclipse.
    • Drag and drop IntelliJ into Applications folder.

Anatomy of a Java Program

  • Functions: Building blocks in Java.
    • Block of code that performs a task.
    • Example functions: Sending emails, validating input.

Creating Functions

  • Start with return type (e.g., void).
  • Function name should be descriptive (e.g., sendEmail).
  • Curly braces {} define code block.
  • Main function is public static void main(String[] args) (entry point of every Java application).

Class Structure

  • Classes: Containers for related functions (methods).
    • At least one class must contain the main function.
    • Use access modifiers: public, private, etc.

Naming Conventions

  • Pascal case for classes (First letter of each word is uppercase).
  • Camel case for methods (First letter of the first word is lowercase, first letter of subsequent words is uppercase).

Writing Your First Java Program

  • Create a new Java project (e.g., "HelloWorld").
  • Code to print "Hello World!" using System.out.println("Hello World!");.
    • Use shortcuts for executing code (e.g., Ctrl + R in IntelliJ).

Execution Process

  1. Compilation & Execution
    • Java code compiled into bytecode using JDK.
  2. Java Virtual Machine (JVM)
    • Converts bytecode into native code for the host OS.

Facts About Java

  • Developed by James Gosling in 1995 at Sun Microsystems.
  • Four editions: Standard, Enterprise, Micro, Card.
  • Java is platform-independent.
  • Search for Java APIs for frequently used classes.

Course Structure

  • Part 1: Fundamentals of programming with Java.
  • Part 2: Object-oriented programming.
  • Part 3: Core Java APIs.
  • Part 4: Advanced Java features (streams, threads, database programming).

Variables and Constants

  • Use variables to store data temporarily.
  • Constants (final keyword) do not change once assigned.
  • Naming conventions: Use descriptive names, camelCase for variables.

Primitive and Reference Types

  • Primitive Types: (byte, short, int, long, float, double, char, boolean).
  • Reference Types: Store references to objects.

Expressions and Operators

  • Arithmetic operators: +, -, *, /, % (modulus).
  • Increment and decrement operators (++, --).
  • Compound assignment operators (+=, -=).*

Control Flow Statements

  1. If statements for conditionals.
  2. Switch statements for alternative branches.
  3. Loops:
    • For loops.
    • While loops.
    • Do-while loops.
    • For-each loops for iterating over arrays.
  4. Break and Continue statements.

Clean Code Practices

  • Write understandable and maintainable code.
  • Use meaningful names for methods, variables, and classes.
  • Break down long methods into smaller methods.

Error Handling and Input Validation

  • Use loops to validate user input while handling errors gracefully.
  • Use Scanner to read user inputs and validate against expected values.

Practice Project: Mortgage Calculator

  • Calculation involves principal, interest rates, and time period.
  • Validate inputs and enhance the calculator using methods for clarity.

Final Tips

  • Always aim for clean, readable code.
  • Familiarize yourself with the Java ecosystem and community practices.