Class 12 Information Technology - Java Programming Fundamentals

Introduction

• Java: A high-level programming language used to create various types of computer applications.
• Key Concepts:
  • Bytecode
  • Java Virtual Machine (JVM)
  • Platform Independence
• Important questions can be expected from these topics in board exams.

Bytecode

• Java Compiler: Translates Java code into bytecode, not directly into machine language code.
• Java Interpreter/JVM: Translates bytecode into machine code and executes it.
• Benefits:
  • Bytecode can run on any platform supporting JVM.
  • Ensures platform independence and high portability.

Java Programming Tools

• Text Editor and Java Compiler: Required to write and compile Java programs.
• Java IDE (Integrated Development Environment): Combines text editor and compiler for ease; example: NetBeans.
• NetBeans IDE: Open-source software, free to download; previous videos provide download instructions.

Comments in Java

• Used to explain code; ignored during compilation.
• Single-line comments: // comment
• Multi-line comments: /* comments */

Packages

• Package: A group of related classes sharing data and code.

Methods

• Method: A group of statements to perform a specific task.
• Main Method: Essential in every Java application; executes first when a program runs.
• Java Statements: End with a semicolon (;).

System.out.println vs System.out.print

• println(): Prints text followed by a new line.
• print(): Prints text on the same line.

Variables

• Variable: A placeholder for data, with value changeable during execution.
• Declaration: Specify data type and variable name.
• Primitive Data Types: Eight types (byte, short, int, long, float, double, char, boolean).

Data Types and Their Sizes

• Integers: byte (1 byte), short (2 bytes), int (4 bytes), long (8 bytes)
• Floating points: float (4 bytes), double (8 bytes)
• Character: char (2 bytes)
• Boolean: boolean (1 bit)

Variable Naming Rules

• Start with a letter (not a digit).
• Use alphabets, digits, or underscores (no special characters other than underscore).
• Variable names should be meaningful.
• Reserved words and case-sensitive.

Operators

• Arithmetic Operators: + - * / %.
• Increment/Decrement: ++/--.
• Relational Operators: <, >, <=, >=, ==, !=.
• Assignment Operator: =.
• Logical Operators: && (AND), || (OR), ! (NOT).

Conditional Statements

• if-else statements: Executes code based on a condition; syntax-sensitive.
• switch statement: Tests a variable against multiple values (cases).
• while loop: Repeats code as long as a condition is true.
• do-while loop: Executes code first, then tests the condition.
• for loop: Iterates a segment of code with initial value, condition, and increment/decrement.

Arrays

• Store multiple values of the same type.
• Defined by specifying the data type, array name, and size.
• Index starts from 0.

User-Defined Methods

• Methods with return type, method name, optional parameters, and body.
• void: Indicates no return value.

Object-Oriented Programming

• Class: A template for creating objects (instances).
• Constructor: Special method for initializing objects; shares the name of the class.
• Access Modifiers: Private, public, default.
• Package Import: Use import keyword for importing classes from packages.

Wrapper Classes

• Enclose primitive data types in objects.
• Example: Integer, Double, etc.
• Provide methods like parseInt, toString.

Exception Handling

• Exception: Unexpected events disrupting the normal flow of execution.
• try-catch block: Handles exceptions; try contains code that might throw an exception, catch handles the exception.
• Specific use-case: Division by zero.

Threads

• Used for performing multiple tasks simultaneously.
• Created by extending Thread class or implementing Runnable interface.

Important Methods and Examples

• String Class Methods: charAt, concat, contains, endsWith, length, replace, etc.
• Arrays Methods: sort, binarySearch (requires sorted array).
• Assertion: Debugging tool to test assumptions in the code.

Lab Exercises

• Practice writing different programs; refer to sample papers for additional questions.