Java Module 001: Week 1 - Java Basics

This module covers the foundational concepts of Java, including setup, basic syntax, data types, variables, constants, and operators. Designed for beginners, it includes explanations, code examples, and practice exercises for each day of Week 1. By the end, you'll write simple programs and understand Java's core components.

Day 1: Introduction to Java

Objective: Understand Java's ecosystem and write your first program.

Explanation

Java Overview:
- JDK (Java Development Kit): Tools for developing Java programs (compiler, libraries).
- JRE (Java Runtime Environment): Runs Java programs (includes JVM and libraries).
- JVM (Java Virtual Machine): Executes Java bytecode, enabling platform independence.
First Program: A Java program starts with a main method, the entry point. Use System.out.println to print output to the console.

Code Example

public class HelloWorld {
    public static void main(String[] args) {
        System.out.println("Hello, World!");
    }
}

Practice

Install the JDK (e.g., OpenJDK or Oracle JDK).
Write a program to print your name and a welcome message.
Run the program using a terminal or IDE (e.g., IntelliJ, Eclipse).

Practice Code:

public class MyFirstProgram {
    public static void main(String[] args) {
        System.out.println("My name is [Your Name]");
        System.out.println("Welcome to Java!");
    }
}

Day 2: Comments, Data Types, and Variables

Objective: Learn to document code with comments and use basic data types and variables.

Explanation

Comments:
- Single-line: // This is a comment
- Multi-line: /* This is a multi-line comment */
Data Types:
- Primitive: int (integer), double (decimal), char (single character), boolean (true/false).
- Example: int age = 25; double price = 19.99; char grade = 'A'; boolean isStudent = true;
Variables: Named storage for data, declared with a type (e.g., int number;).
Constants: Use final to make variables unchangeable (e.g., final double PI = 3.14159;).

Code Example

public class DataTypesExample {
    public static void main(String[] args) {
        // Declare variables
        int age = 25;
        double salary = 50000.50;
        char initial = 'J';
        boolean isEmployed = true;
        final double TAX_RATE = 0.1;

        // Print variables
        System.out.println("Age: " + age);
        System.out.println("Salary: " + salary);
        System.out.println("Initial: " + initial);
        System.out.println("Employed: " + isEmployed);
        System.out.println("Tax Rate: " + TAX_RATE);
    }
}

Practice

Write a program to declare and print variables of int, double, char, and boolean types.
Create a constant for a maximum score (e.g., 100) and print it.
Add single-line and multi-line comments to explain your code.

Practice Code:

public class VariablesPractice {
    public static void main(String[] args) {
        // Declaring variables
        int score = 85;
        double price = 29.99;
        char grade = 'B';
        boolean isPassing = true;
        final int MAX_SCORE = 100;

        /* Printing variable values
           to demonstrate data types */
        System.out.println("Score: " + score);
        System.out.println("Price: " + price);
        System.out.println("Grade: " + grade);
        System.out.println("Passing: " + isPassing);
        System.out.println("Max Score: " + MAX_SCORE);
    }
}

Day 3: Non-Primitive Types and String Operations

Objective: Work with String (non-primitive type) and perform basic string operations.

Explanation

Non-Primitive Types: Unlike primitives, these are objects (e.g., String, arrays).
String: Represents text, created with quotes (e.g., String name = "Alice";).
Common String operations:
- Concatenation: + (e.g., "Hello, " + name).
- Methods: .length(), .toUpperCase(), .toLowerCase().

Code Example

public class StringExample {
    public static void main(String[] args) {
        String name = "Alice";
        String greeting = "Hello, " + name + "!";
        
        System.out.println(greeting);
        System.out.println("Name length: " + name.length());
        System.out.println("Uppercase: " + name.toUpperCase());
    }
}

Practice

Create a program to declare a String variable for your name and concatenate it with a greeting.
Print the length of the string and convert it to uppercase.
Use a constant String for a fixed message (e.g., "Welcome").

Practice Code:

public class StringPractice {
    public static void main(String[] args) {
        String name = "[Your Name]";
        final String WELCOME = "Welcome to Java!";
        String message = WELCOME + " " + name;

        System.out.println(message);
        System.out.println("Name length: " + name.length());
        System.out.println("Message in uppercase: " + message.toUpperCase());
    }
}

Day 4: Arithmetic Operators

Objective: Use arithmetic operators to perform calculations.

Explanation

Arithmetic Operators:
- + (addition), - (subtraction), * (multiplication), / (division), % (modulus).
- Example: int sum = 5 + 3; int remainder = 10 % 3; // remainder is 1
Division:
- Integer division truncates decimals (e.g., 5 / 2 = 2).
- Use double for decimal results (e.g., 5.0 / 2 = 2.5).

Code Example

public class ArithmeticExample {
    public static void main(String[] args) {
        int a = 10, b = 3;
        System.out.println("Addition: " + (a + b));
        System.out.println("Subtraction: " + (a - b));
        System.out.println("Multiplication: " + (a * b));
        System.out.println("Division: " + (a / b));
        System.out.println("Modulus: " + (a % b));
        System.out.println("Decimal Division: " + (a / (double)b));
    }
}

Practice

Write a program to calculate the area of a rectangle (length * width).
Compute the remainder when dividing two numbers.
Perform division with decimal output using type casting.

Practice Code:

public class ArithmeticPractice {
    public static void main(String[] args) {
        int length = 10, width = 5;
        int area = length * width;
        int num1 = 17, num2 = 4;
        
        System.out.println("Rectangle Area: " + area);
        System.out.println("Remainder of " + num1 + " / " + num2 + ": " + (num1 % num2));
        System.out.println("Decimal Division: " + (num1 / (double)num2));
    }
}

Day 5: Comparison and Logical Operators

Objective: Use comparison and logical operators for decision-making.

Explanation

Comparison Operators:
- == (equal), != (not equal), > (greater), < (less), >=, <=.
- Example: int x = 5; boolean isEqual = (x == 5); // true
Logical Operators:
- && (AND), || (OR), ! (NOT).
- Example: boolean result = (x > 0 && x < 10); // true if x is between 0 and 10

Code Example

public class OperatorsExample {
    public static void main(String[] args) {
        int number = 7;
        boolean isPositive = number > 0;
        boolean isEven = number % 2 == 0;
        boolean isValid = isPositive && !isEven;

        System.out.println("Is " + number + " positive? " + isPositive);
        System.out.println("Is " + number + " even? " + isEven);
        System.out.println("Is positive and odd? " + isValid);
    }
}

Practice

Write a program to check if a number is positive and even.
Use logical operators to check if a number is between 1 and 100.
Combine comparison and logical operators to validate input.

Practice Code:

public class OperatorsPractice {
    public static void main(String[] args) {
        int number = 42;
        boolean isPositive = number > 0;
        boolean isEven = number % 2 == 0;
        boolean inRange = number >= 1 && number <= 100;

        System.out.println(number + " is positive: " + isPositive);
        System.out.println(number + " is even: " + isEven);
        System.out.println(number + " is between 1 and 100: " + inRange);
    }
}

Weekend: Review and Mini-Project

Objective: Consolidate Week 1 learning with a small project.

Review

Revisit:
- JDK/JRE/JVM roles.
- Comments, data types, variables, constants.
- String operations and arithmetic operators.
- Comparison and logical operators.
Debug common errors (e.g., missing ;, wrong data types).

Mini-Project: Personal Info Program

Create a console-based program that:

Stores your name (String), age (int), height (double), and student status (boolean).
Uses a constant for a maximum age (e.g., 120).
Performs calculations (e.g., height in meters if given in cm).
Checks if the person is a student and age is valid (0 to max age).
Prints all details with appropriate formatting.

Project Code:

public class PersonalInfo {
    public static void main(String[] args) {
        // Declare variables and constant
        String name = "[Your Name]";
        int age = 25;
        double heightCm = 175.5;
        boolean isStudent = true;
        final int MAX_AGE = 120;

        // Perform calculations
        double heightMeters = heightCm / 100;
        boolean isAgeValid = age > 0 && age <= MAX_AGE;

        // Print details
        System.out.println("Personal Information:");
        System.out.println("Name: " + name);
        System.out.println("Age: " + age + " (Valid: " + isAgeValid + ")");
        System.out.println("Height: " + heightMeters + " meters");
        System.out.println("Student: " + isStudent);
    }
}

Weekend Practice

Run and test the project with different inputs.
Add comments to explain each section.
Modify the program to include another calculation (e.g., age in months).

Tips for Week 1

Practice: Run each code example in an IDE or terminal.
Debug: Check for syntax errors (e.g., missing semicolons, incorrect capitalization).
Resources: Use Oracle’s Java Tutorials or W3Schools for reference.
Experiment: Try modifying code examples to see how changes affect output.

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Java Module 001: Week 1 - Java Basics

Day 1: Introduction to Java

Explanation

Code Example

Practice

Day 2: Comments, Data Types, and Variables

Explanation

Code Example

Practice

Day 3: Non-Primitive Types and String Operations

Explanation

Code Example

Practice

Day 4: Arithmetic Operators

Explanation

Code Example

Practice

Day 5: Comparison and Logical Operators

Explanation

Code Example

Practice

Weekend: Review and Mini-Project

Review

Mini-Project: Personal Info Program

Weekend Practice

Tips for Week 1

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Java Module 001: Week 1 - Java Basics

Day 1: Introduction to Java

Explanation

Code Example

Practice

Day 2: Comments, Data Types, and Variables

Explanation

Code Example

Practice

Day 3: Non-Primitive Types and String Operations

Explanation

Code Example

Practice

Day 4: Arithmetic Operators

Explanation

Code Example

Practice

Day 5: Comparison and Logical Operators

Explanation

Code Example

Practice

Weekend: Review and Mini-Project

Review

Mini-Project: Personal Info Program

Weekend Practice

Tips for Week 1