Introduction to Java Programming

• Java is a high-level, class-based, object-oriented programming language designed to minimize implementation dependencies

Key Features of Java

• Object-oriented approach handles everything as objects, integrating data with behavior
• Platform independence is achieved through the Java Virtual Machine (JVM), enabling "write once, run anywhere" (WORA)
• Designed for ease of use, featuring simplified syntax compared to languages like C++
• Emphasis on secure coding and execution to protect against malicious code
• Employs strong memory management and exception handling to prevent crashes
• Supports concurrent execution of multiple threads for efficient resource utilization
• Platform independent allowing it to run on diverse operating systems and hardware
• Achieves performance comparable to native languages using just-in-time (JIT) compilation
• Facilitates the creation of distributed applications
• Adapts to changing environments more readily than languages like C or C++

Java Virtual Machine (JVM)

• JVM is essential for Java's platform independence
• Functions as an abstract computing machine that allows computers to run Java programs
• Interprets and executes bytecode generated by the Java compiler on the host machine
• Different JVM implementations enable Java programs to run across various operating systems without changes
• Key functions: loading, verifying, and executing bytecode, along with runtime services like memory management and garbage collection

Java Development Kit (JDK)

• JDK serves as a software development environment for creating Java applications
• Provides tools for writing, compiling, debugging, and running Java code
• The Java compiler (javac) translates Java source code into bytecode
• Java Runtime Environment (JRE) supplies necessary libraries and the JVM to run Java programs
• Includes debugging tools (jdb) and documentation tools (javadoc)

Basic Java Syntax

• Java programs are structured into classes
• Classes contain fields which are data(variables) and behavior in the form of methods (functions) that manipulate data
• The main method acts as the entry point, declared as public static void main(String[] args)
• Statements conclude with a semicolon (;)
• Case-sensitive language

Data Types

• Commonly used primitive data types:
  • int for integers
  • double for floating-point numbers
  • boolean for true/false values
  • char for single characters
• Reference data types:
  • Classes
  • Interfaces
  • Arrays

Variables

• Declaration of variables with specific data types is mandatory before use
• Assignment operator (=) assigns values to variables
• Declaring variables as final prevents modification after initialization

Operators

• Arithmetic operators: +, -, *, /, % (modulus)
• Relational operators: == (equal to), != (not equal to), >, =, ``).
• Lambda expressions are often used with functional interfaces, which are interfaces with a single abstract method.

Java API

• The Java API (Application Programming Interface) is a vast collection of pre-written classes that are ready to use
• The API is organized into packages.
• java.lang, java.util, java.io, java.net, javax.swing are useful packages

Best Practices

• Write clean, readable code using appropriate variable and method names
• Adhere to Java coding conventions
• Use comments to clarify code sections
• Handle exceptions to maintain program stability
• Prevent memory leaks
• Focus on code optimization for better performance