Java Basic Practice Question

Q: Fibonacci series.

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter number: ");
        int n = input.nextInt();
        int a = 0;
        int b = 1;
        int count = 2;

        while(count <= n) {
            int temp = b;
            b += a;
            a = temp;
            count++;
        }
        System.out.println(b);
    }
}

Q: 

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        // Find occurence of a number.
        int n = 4345;
        int findNum = 4;
        int count = 0;

        while(n > 0) {
            int res = n % 10;
            if(res == findNum){
                count++;
            }
            n /= 10;
        }
        System.out.println(count);

        // Way - 2
        fo(int i=0; i<)
    
    }
}

Q: 

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        int num = 4345;

//        Way - 1
//        while(num > 0) {
//            int rem = num % 10;
//            num /= 10;
//            System.out.print(rem);
//        }

//        Way - 2
        int ans = 0;
        while(num > 0) {
            int rem = num % 10;
            num /= 10;
            ans = ans * 10 + rem;
        }
        System.out.print(ans);
    }
}

Q: 

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
//        Basic Calculator
        Scanner input = new Scanner(System.in);
        int ans = 0;

        while(true) { // take input from user till user does not press 'e' or 'E'
            System.out.print("Enter operation: (+, -, *, /, %, & e, E to exit): ");
            char op = input.next().trim().charAt(0); // take the operator as input
            if(op == '+' || op == '-' || op == '*' || op == '%' || op =='/') {
                System.out.print("Enter two numbers: ");
//                Input two numbers
                int num1, num2;
                try {
                    num1 = input.nextInt();
                    num2 = input.nextInt();
                } catch (Exception e) {
                    System.out.println("Invalid input! Please enter valid integers.");
                    input.nextLine(); // Clear the buffer
                    continue;
                }

                if(op == '+') {
                    ans = num1 + num2;
                }
                else if(op == '-') {
                    ans = num1 - num2;
                }
                else if(op == '*') {
                    ans = num1 * num2;
                }
                else if(op == '%') {
                    if(num2 == 0) {
                        System.out.println("NaN");
                        continue;
                    }
                    else {
                        ans = num1 % num2;
                    }
                }
                else if(op == '/') {
                    if(num2 == 0) {
                        System.out.println("NaN");
                        continue;
                    }
                    else {
                        ans = num1 / num2;
                    }
                }

                System.out.println("Answer is: " + ans);

            }
            else if(op == 'e' || op == 'E') {
                System.out.println("Exiting the calculator. Goodbye!");
                break;
            }
            else {
                System.out.println("Invaild operator! Please try again.");
            }
        }

        input.close(); // Close the scanner to prevent resource leaks
    }
}

Q: 

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
    
    }
}

Q: 

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
    
    }
}