Top Java Interview Programs

 In this post, we are going to cover most asked java interview programs.

1. A Prime Number

Write a java program to check given number is prime or not.

Java Program:

public class PrimeCheck{
public static void main(String args[]){
int i,m=0,flag=0;
int n=3;
m=n/2;
if(n==0||n==1){
System.out.println(n+" is not a prime number.");
}
else{
for(i=2;i<=m;i++){
if(n%i==0){
System.out.println(n+" is not a prime number.");
flag=1;
break;
}
}
if(flag==0) { System.out.println(n+" is a prime number."); }}}}

2. Verify a number is Even/Odd

Write java program to find number is even or odd.

Java Program:

import java.util.Scanner;

public class EvenOdd {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        System.out.println("Enter a number which you want to check whether that is even or odd");
        int n = in .nextInt();

        if (n % 2 == 0) {
            System.out.println(n + " is an even number.");
        } else {
            System.out.println(n + " is an odd number.");

        }
    }
}

3. Swap a Numbers without using the third variable's:

Write java program to swap a numbers without using third variables.

Java Program:

import java.util.Scanner;

public class Swapping {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        System.out.println("Enter the 1st number: ");
        int x = in .nextInt();
        System.out.println("Enter the 2nd number: ");
        int y = in .nextInt();

        System.out.println("Initial value of x: " + x + " and y: " + y);

        x = x + y;
        y = x - y;
        x = x - y;

        System.out.println("After swapping value of x: " + x + " and y: " + y);
    }
}

4. Verify Number is Armstrong or not

Write a Java program to verify given number is Armstrong or not.

Java Program:

import java.util.Scanner;

public class ArmstrongNum {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        System.out.println("Enter a number which you want to check whether that is armstrong or not: ");
        int n = in .nextInt();
        int a = n, r = 0, s = 0;

        while (a != 0) {
            r = a % 10;
            a = a / 10;
            s = s + r * r * r;
        }
        if (s == n) {
            System.out.println("Number " + n + " is an armstrong number.");
        } else {
            System.out.println("Number " + n + " is not an armstrong number.");
        }
    }
}

5. Factorial of number:

Write a java program to find factorial of given number

Java Program:

import java.util.Scanner;

public class Factorial {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        System.out.println("Enter the number whose factorial you want: ");
        int n = in .nextInt();
        int f = 1;
        for (int i = n; i > 0; i--) {
            f = f * i;
        }
        System.out.println("Factorial of " + n + " is " + f);
    }
}