OBJECT ORIENTED PROGRAMMING THROUGH JAVA : Unit - 1 : Conditional Statements

Conditional Statements in Java

In Java, conditional statements are used to perform different actions based on different conditions. They control the flow of execution in a program based on whether a condition is true or false.

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Types of Conditional Statements in Java

1. if Statement

2. if-else Statement

3. if-else-if Ladder

4. nested if Statement

5. switch Statement

6. ternary (?:) Operator (alternative to if-else)

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1. if Statement

Syntax:

if (condition) {
    // statements to execute if condition is true
}

Example:

public class IfDemo {
    public static void main(String[] args) {
        int age = 20;
        if (age >= 18) {
            System.out.println("You are eligible to vote.");
        }
    }
}

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2. if-else Statement

Syntax:

if (condition) {
    // if block
} else {
    // else block
}

Example:

public class IfElseDemo {
    public static void main(String[] args) {
        int number = 10;
        if (number % 2 == 0) {
            System.out.println("Even number");
        } else {
            System.out.println("Odd number");
        }
    }
}

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3. if-else-if Ladder

Used when there are multiple conditions to check.

Syntax:

if (condition1) {
    // statements
} else if (condition2) {
    // statements
} else {
    // default block
}

Example:

public class IfElseIfDemo {
    public static void main(String[] args) {
        int marks = 75;
        if (marks >= 90) {
            System.out.println("Grade A");
        } else if (marks >= 75) {
            System.out.println("Grade B");
        } else if (marks >= 60) {
            System.out.println("Grade C");
        } else {
            System.out.println("Fail");
        }
    }
}

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4. nested if Statement

An if statement inside another if statement.

Syntax:

if (condition1) {
    if (condition2) {
        // nested block
    }
}

Example:

public class NestedIfDemo {
    public static void main(String[] args) {
        int age = 25;
        String nationality = "Indian";
        if (nationality.equals("Indian")) {
            if (age >= 18) {
                System.out.println("You are eligible to vote in India.");
            }
        }
    }
}

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Java Assignment Programs – Conditional Statements

🔹 Beginner Level

1. Check if a number is positive or negative.

2. Check if a number is even or odd.

3. Find the greatest of two numbers.

4. Find the greatest of three numbers.

5. Check if a person is eligible to vote (age ≥ 18).

6. Check if a year is a leap year.

7. Check if a character is a vowel or consonant.

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🔹 Intermediate Level

8. Find the largest among three numbers using if-else-if ladder.

9. Check whether a number is divisible by 5 and 11.

10. Check if a character is uppercase, lowercase, digit, or special character.

11. Calculate grade based on marks using if-else-if.

12. Check if a number is positive, negative, or zero.

13. Check whether a number is even or odd using ternary operator.

14. Menu-driven program using switch for basic calculator (add, subtract, multiply, divide).

15. Find whether a given number is a multiple of 3, 5, or both.

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🔹 Advanced Level

16. Accept a 3-digit number and check whether it is an Armstrong number.

17. Accept a character and check if it's an alphabet. If yes, whether it is vowel or consonant.

18. Accept three sides of a triangle and check whether it is valid, and if yes, what type of triangle it is.

19. Write a switch case to print the day of the week based on a number (1–7).

20. Using nested if, check whether a student has passed based on subject-wise marks and overall average.