20 important Java programs based on conditional statements

20 important Java programs based on conditional statements, demonstrating how to use if, else, else if, and switch-case statements:

Check Even or Odd

• Explanation: Check whether a given number is even or odd.

CODE

import java.util.Scanner;

public class EvenOdd {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        System.out.print("Enter a number: ");

        int num = sc.nextInt();

        if (num % 2 == 0) {

            System.out.println(num + " is even");

        } else {

            System.out.println(num + " is odd");

        }

    }

}

Check Positive, Negative or Zero

• Explanation: Check if a number is positive, negative, or zero.

CODE

import java.util.Scanner;

public class PositiveNegativeZero {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        System.out.print("Enter a number: ");

        int num = sc.nextInt();

        if (num > 0) {

            System.out.println("The number is positive.");

        } else if (num < 0) {

            System.out.println("The number is negative.");

        } else {

            System.out.println("The number is zero.");

        }

    }

}

Find Largest of Three Numbers

• Explanation: Find the largest number among three given numbers.

CODE

import java.util.Scanner;

public class LargestNumber {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        System.out.print("Enter three numbers: ");

        int num1 = sc.nextInt();

        int num2 = sc.nextInt();

        int num3 = sc.nextInt();

        if (num1 >= num2 && num1 >= num3) {

            System.out.println(num1 + " is the largest number.");

        } else if (num2 >= num1 && num2 >= num3) {

            System.out.println(num2 + " is the largest number.");

        } else {

            System.out.println(num3 + " is the largest number.");

        }

    }

}

Check Vowel or Consonant

• Explanation: Check whether a given character is a vowel or consonant.

CODE

import java.util.Scanner;

public class VowelConsonant {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        System.out.print("Enter a character: ");

        char ch = sc.next().charAt(0);

        if (ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch == 'u' ||

            ch == 'A' || ch == 'E' || ch == 'I' || ch == 'O' || ch == 'U') {

            System.out.println(ch + " is a vowel.");

        } else {

            System.out.println(ch + " is a consonant.");

        }

    }

}

Check Leap Year

• Explanation: Check if a given year is a leap year.

CODE

import java.util.Scanner;

public class LeapYear {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        System.out.print("Enter a year: ");

        int year = sc.nextInt();

        if ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0)) {

            System.out.println(year + " is a leap year.");

        } else {

            System.out.println(year + " is not a leap year.");

        }

    }

}

Find the Grade Based on Marks

• Explanation: Determine the grade based on marks.

CODE

import java.util.Scanner;

public class Grade {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        System.out.print("Enter marks: ");

        int marks = sc.nextInt();

        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 if (marks >= 40) {

            System.out.println("Grade D");

        } else {

            System.out.println("Fail");

        }

    }

}

Check Alphabet, Digit, or Special Character

• Explanation: Check if a character is an alphabet, digit, or special character.

CODE

import java.util.Scanner;

public class CharType {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        System.out.print("Enter a character: ");

        char ch = sc.next().charAt(0);

        if (Character.isAlphabetic(ch)) {

            System.out.println(ch + " is an alphabet.");

        } else if (Character.isDigit(ch)) {

            System.out.println(ch + " is a digit.");

        } else {

            System.out.println(ch + " is a special character.");

        }

    }

}

Switch Case for Days of the Week

• Explanation: Print the name of the day based on the input number using switch.

CODE

import java.util.Scanner;

public class DayOfWeek {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        System.out.print("Enter a number (1-7): ");

        int day = sc.nextInt();

        switch (day) {

            case 1: System.out.println("Monday"); break;

            case 2: System.out.println("Tuesday"); break;

            case 3: System.out.println("Wednesday"); break;

            case 4: System.out.println("Thursday"); break;

            case 5: System.out.println("Friday"); break;

            case 6: System.out.println("Saturday"); break;

            case 7: System.out.println("Sunday"); break;

            default: System.out.println("Invalid day!");

        }

    }

}

Simple Calculator (Switch Case)

• Explanation: Implement a simple calculator using switch for basic operations.

CODE

import java.util.Scanner;

public class Calculator {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        System.out.print("Enter first number: ");

        double num1 = sc.nextDouble();

        System.out.print("Enter second number: ");

        double num2 = sc.nextDouble();

        System.out.print("Enter operation (+, -, *, /): ");

        char operator = sc.next().charAt(0);

        double result;

        switch (operator) {

            case '+': result = num1 + num2; break;

            case '-': result = num1 - num2; break;

            case '*': result = num1 * num2; break;

            case '/': result = num1 / num2; break;

            default:

                System.out.println("Invalid operator");

                return;

        }

        System.out.println("Result: " + result);

    }

}

 Check Armstrong Number

• Explanation: Check if a number is an Armstrong number.

CODE

import java.util.Scanner;

public class Armstrong {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        System.out.print("Enter a number: ");

        int num = sc.nextInt();

        int sum = 0, temp, remainder, digits = 0;

        temp = num;

        while (temp != 0) {

            temp /= 10;

            digits++;

        }

        temp = num;

        while (temp != 0) {

            remainder = temp % 10;

            sum += Math.pow(remainder, digits);

            temp /= 10;

        }

        if (sum == num) {

            System.out.println(num + " is an Armstrong number.");

        } else {

            System.out.println(num + " is not an Armstrong number.");

        }

    }

}

Check Strong Number

• Explanation: Check if a number is a Strong number (factorial sum equals the number).

CODE

import java.util.Scanner;

public class StrongNumber {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        System.out.print("Enter a number: ");

        int num = sc.nextInt();

        int sum = 0, temp = num;

        while (temp != 0) {

            int digit = temp % 10;

            sum += factorial(digit);

            temp /= 10;

        }

        if (sum == num) {

            System.out.println(num + " is a Strong number.");

        } else {

            System.out.println(num + " is not a Strong number.");

        }

    }

 

    public static int factorial(int n) {

        int fact = 1;

        for (int i = 1; i <= n; i++) {

            fact *= i;

        }

        return fact;

    }

}

Check Palindrome

• Explanation: Check if a given string is a palindrome.

CODE

import java.util.Scanner;

public class Palindrome {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        System.out.print("Enter a string: ");

        String str = sc.nextLine();

        String reverse = new StringBuilder(str).reverse().toString();

        if (str.equals(reverse)) {

            System.out.println(str + " is a palindrome.");

        } else {

            System.out.println(str + " is not a palindrome.");

        }

    }

}

Find Maximum of N Numbers

• Explanation: Find the largest of n numbers using conditional statements.

CODE

import java.util.Scanner;

public class MaximumOfN {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        System.out.print("Enter the number of elements: ");

        int n = sc.nextInt();

        int max = Integer.MIN_VALUE;

        for (int i = 0; i < n; i++) {

            System.out.print("Enter number " + (i + 1) + ": ");

            int num = sc.nextInt();

            if (num > max) {

                max = num;

            }

        }

        System.out.println("The largest number is " + max);

    }

}

Check Triangle Validity

• Explanation: Check whether three sides form a valid triangle.

CODE

import java.util.Scanner;

public class TriangleValidity {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        System.out.print("Enter three sides of a triangle: ");

        int a = sc.nextInt();

        int b = sc.nextInt();

        int c = sc.nextInt();

        if (a + b > c && a + c > b && b + c > a) {

            System.out.println("Valid triangle.");

        } else {

            System.out.println("Invalid triangle.");

        }

    }

}

Check Divisibility by 3 and 5

• Explanation: Check if a number is divisible by both 3 and 5.

CODE

import java.util.Scanner;

public class DivisibleBy3and5 {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        System.out.print("Enter a number: ");

        int num = sc.nextInt();

        if (num % 3 == 0 && num % 5 == 0) {

            System.out.println(num + " is divisible by both 3 and 5.");

        } else {

            System.out.println(num + " is not divisible by both 3 and 5.");

        }

    }

}

Check Armstrong for a Range

• Explanation: Check Armstrong numbers in a given range.

CODE

public class ArmstrongRange {

    public static void main(String[] args) {

        for (int num = 1; num <= 999; num++) {

            int sum = 0, temp = num;

            int digits = String.valueOf(num).length();

            while (temp != 0) {

                int remainder = temp % 10;

                sum += Math.pow(remainder, digits);

                temp /= 10;

            }

            if (sum == num) {

                System.out.println(num + " is an Armstrong number.");

            }

        }

    }

}

Find Day of the Week Using Switch

• Explanation: Find the name of the day based on the number using switch.

CODE

import java.util.Scanner;

public class DayOfWeek {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        System.out.print("Enter day number (1-7): ");

        int day = sc.nextInt();

        switch (day) {

            case 1: System.out.println("Monday"); break;

            case 2: System.out.println("Tuesday"); break;

            case 3: System.out.println("Wednesday"); break;

            case 4: System.out.println("Thursday"); break;

            case 5: System.out.println("Friday"); break;

            case 6: System.out.println("Saturday"); break;

            case 7: System.out.println("Sunday"); break;

            default: System.out.println("Invalid day!"); break;

        }

    }

}

Find the Largest Digit

• Explanation: Find the largest digit in a number.

CODE

import java.util.Scanner;

public class LargestDigit {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        System.out.print("Enter a number: ");

        int num = sc.nextInt();

        int largest = 0;

        while (num != 0) {

            int digit = num % 10;

            if (digit > largest) {

                largest = digit;

            }

            num /= 10;

        }

        System.out.println("Largest digit: " + largest);

    }

}

Find the Sum of Natural Numbers

• Explanation: Find the sum of first n natural numbers.

CODE

import java.util.Scanner;

public class SumNaturalNumbers {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        System.out.print("Enter a number: ");

        int n = sc.nextInt();

        int sum = (n * (n + 1)) / 2;

        System.out.println("Sum of first " + n + " natural numbers: " + sum);

    }

}

Check Divisibility by 7

• Explanation: Check if a number is divisible by 7.

CODE

import java.util.Scanner;

public class DivisibleBySeven {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        System.out.print("Enter a number: ");

        int num = sc.nextInt();

        if (num % 7 == 0) {

            System.out.println(num + " is divisible by 7.");

        } else {

            System.out.println(num + " is not divisible by 7.");

        }

    }

}