Introduction to Java Programming

Java Introduction and Features

• Java is a programming language that has been in existence since 1995
• Java was invented by James Gosling
• Initially created for interactive television, but its features made it suitable for other purposes
• Key features of Java:
  • Open source
  • High performance
  • Multi-threading
  • Secure
  • Platform independent
  • Portable (write once, run anywhere)
  • Robust (error-free)

Java Installation

• To download Java, search for "Java download for Windows"
• Select the Oracle JDK version suitable for your system
• Accept the license agreement and download the JDK
• Create a new variable "Java Home" with the path to the JDK
• Set the path to the JDK in the environment variables
• Verify Java installation by checking the version in the command prompt

Eclipse IDE Installation

• Download Eclipse IDE from the Eclipse Foundation website
• Select the Eclipse IDE for Java developers
• Install Eclipse IDE
• Create a new Java project in Eclipse
• Create a new package and class in the project
• Write and run a simple "Hello World" program

Variables in Java

• A variable is a container that holds a value during program execution
• Types of variables:
  • Local variable (declared inside a method)
  • Instance variable (declared inside a class, but outside a method)
  • Static variable (shared by all instances of a class)

Data Types in Java

• Primitive data types in Java:
  • int (2 bytes)
  • float (4 bytes)
  • double (8 bytes)
  • long (8 bytes)
  • short (2 bytes)
  • char (2 bytes)
  • byte (1 byte)
  • boolean (1 byte)

Operators in Java

• Types of operators:
  • Unary operators (++, --, -, !, ~, etc.)
  • Arithmetic operators (+, -, *, /, %)
  • Shift operators (<<, >>, >>>)
  • Relational operators (==, !=, >, <, >=, <=)
  • Bitwise operators (&, |, ^, ~)
  • Logical operators (&&, ||, !)
  • Ternary operator (?:)
  • Assignment operators (=, +=, -=, *=, /=, %=, etc.)

Note: These are the main points from the text. If you want me to add or clarify anything, please let me know!### Relational Operators

• Relational operators compare two values and return a boolean result.
• Example: a < b and a < c.
• The output is false because a is greater than b but not less than b, similarly a is less than c.

Bitwise Operators

• Bitwise operators apply operations on the bits of two values.
• Example: a = 10, b = 5, and c = 20.
• The output changes the value of a from 10 to 11 due to the post-increment operation a++.

Logical Operators

• Logical operators are used to combine two or more relational operators.
• There are three logical operators: and, or, and not.
• and operator returns true if both operands are true.
• or operator returns true if at least one operand is true.
• not operator negates the result of the operand.

Ternary Operators

• Ternary operators are a shorthand for conditional statements.
• Example: minimum = a < b ? a : b.
• If a is less than b, then minimum is a, else it is b.

Assignment Operators

• Assignment operators are used to allocate memory to variables.
• Examples: a = 10, b = 20, a += 4, and b -= 4.
• The output is a = 14 and b = 16.

Control Statements

• Control statements determine the flow of a program.
• There are several types of control statements in Java:
  • if statement
  • while loop
  • do-while loop
  • for loop
  • switch statement

If Statement

• The if statement executes a block of code if the condition is true.
• Example: if (a > 20) { ... } else { ... }.

While Loop

• The while loop executes a block of code while the condition is true.
• Example: while (i <= 15) { ... }.

Do-While Loop

• The do-while loop executes a block of code at least once, then checks the condition.
• Example: do { ... } while (i <= 20).

For Loop

• The for loop initializes a variable, checks a condition, and increments/decrements the variable.
• Example: for (int i = 1; i <= 10; i++) { ... }.

Switch Statement

• The switch statement executes a block of code based on a value.
• Example: switch (instrument) { ... }.

Object-Oriented Programming

• Object-oriented programming is a style of programming that uses concepts like inheritance, polymorphism, abstraction, and encapsulation.
• Encapsulation is a mechanism to bind data and code together as a single unit.
• Example: public class User { ... }.

Inheritance

• Inheritance is a mechanism in which one class inherits properties from another class.

• Types of inheritance:

  • Single inheritance
  • Multi-level inheritance
  • Hierarchical inheritance
  • Hybrid inheritance### Inheritance in Java

• Multiple inheritance or Hybrid inheritance is not supported in Java.

• Java uses interfaces to achieve multiple inheritance.

Abstraction

• Abstraction refers to the quality of dealing with ideas rather than events.
• It involves hiding the details and showing the essential things to the user.
• Abstraction helps reduce code complexity.
• There are two ways to achieve abstraction in Java: using abstract classes or interfaces.

Abstract Classes

• An abstract class in Java contains the abstract keyword.
• A class declared abstract cannot be instantiated, meaning you cannot create an object of an abstract class.
• An abstract class can contain both abstract and concrete methods.

Interfaces

• An interface in Java is a blueprint of a class or a collection of abstract methods and static constants.
• Each method in an interface is public and abstract, but does not contain any constructors.
• Interfaces also help achieve multiple inheritance in Java.

Example of Abstraction using Abstract Class

• The abstract class "Person" is declared with abstract keyword.
• The class "Student" extends the abstract class "Person" and inherits its elements.
• The output of the program generates the name, gender, and student ID of students.

Example of Abstraction using Interface

• The interface "Calculator" is declared with abstract methods for addition, subtraction, multiplication, and division.
• The class "Student" implements the interface to perform mathematical operations.
• The output of the program generates the results of the mathematical operations based on user input.

Java Introduction and Features

• Java is a programming language that has been in existence since 1995.
• It was invented by James Gosling.
• Initially, it was created for interactive television, but its features made it suitable for other purposes.
• Java has several key features, including:
  • Being open source.
  • Having high performance.
  • Supporting multi-threading.
  • Being secure.
  • Being platform-independent.
  • Being portable (write once, run anywhere).
  • Being robust (error-free).

Java Installation

• Download Java by searching for "Java download for Windows" and selecting the Oracle JDK version suitable for your system.
• Accept the license agreement and download the JDK.
• Create a new variable "Java Home" with the path to the JDK.
• Set the path to the JDK in the environment variables.
• Verify Java installation by checking the version in the command prompt.

Eclipse IDE Installation

• Download Eclipse IDE from the Eclipse Foundation website.
• Select the Eclipse IDE for Java developers.
• Install Eclipse IDE.
• Create a new Java project in Eclipse.
• Create a new package and class in the project.
• Write and run a simple "Hello World" program.

Variables in Java

• A variable is a container that holds a value during program execution.
• There are three types of variables:
  • Local variables, declared inside a method.
  • Instance variables, declared inside a class, but outside a method.
  • Static variables, shared by all instances of a class.

Data Types in Java

• Primitive data types in Java include:
  • int (2 bytes).
  • float (4 bytes).
  • double (8 bytes).
  • long (8 bytes).
  • short (2 bytes).
  • char (2 bytes).
  • byte (1 byte).
  • boolean (1 byte).

Operators in Java

• There are several types of operators, including:
  • Unary operators (++, --, -, !, ~, etc.).
  • Arithmetic operators (+, -, *, /, %).
  • Shift operators (, >>>).
  • Relational operators (==, !=, >, =, etc.).

While Loop

• The while loop executes a block of code while the condition is true.
• Example: while (i < 5) { ... } else { ... }.