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Here are my list of 10 Java coding interview questions and answers, which is good to prepare before appearing on any Java interviews. As I said Java coding questions are mostly based on programming, logical analysis and problem solving skill , so better to get it right in first place. Any way you may be able to solve and find answers of these Java coding questions by yourself, but if you stuck do a google, and you can get many alternative ways to solve these problem. Some times knowing more than one way to solve any programming question or coding problem in Java also helps to impress interviewer. This list mainly contains basic programs asked on Interviews.

** **

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."); } } }

**output**

Enter a number which you want to check whether that is even or odd

4

4 is an even number.

**Swapping Numbers without using 3rd variable**

</pre> 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); } } <pre>

**output**

Enter the 1st number:

43

Enter the 2nd number:

56

Initial value of x: 43 and y: 56

After swapping value of x: 56 and y: 43

</pre> 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); } } <pre>

**output**

Enter the number whose factorial you want:

6

Factorial of 6 is 720

**How to get the prime numbers between a given range.**

</pre> package javaTutorial; import java.util.ArrayList; import java.util.Scanner; public class GetPrimeNumbers{ public static void main(String[] args){ Scanner in = new Scanner(System.in); System.out.println("Enter a number from which you want prime number: "); int p1 = in.nextInt(); System.out.println("Enter one more number till which you want prime number: "); int p2 = in.nextInt(); ArrayList<Integer> prime = new ArrayList<Integer>(); int i=2; for(int p=p1; p<=p2; p++){ i=2; for(; i<10; i++){ if(p%i==0 && p!=i){ break; } } if(i==10){ prime.add(p); } } System.out.println("Prime numbers between "+p1+" and "+p2+" are: "); for(int j=0; j<prime.size(); j++){ System.out.print(prime.get(j).toString()+", "); } } } <pre>

**Output**

Enter a number from which you want prime number:

10

Enter one more number till which you want prime number:

30

Prime numbers between 10 and 30 are:

11, 13, 17, 19, 23, 29,

**Check a number is prime or not.**

Note- A number is prime if it is not divisible by any other number except itself.

</pre> import java.util.Scanner; public class PrimeNumber{ public static void main(String[] args){ Scanner in = new Scanner(System.in); System.out.println("Enter a number greater than 2 which you want to check whether that number is prime or not: "); int p = in.nextInt(); int i=2; for(; i<10; i++){ if(p%i==0 && p!=i){ System.out.println("Entered number "+p+" is not a prime number."); break; } } if(i==10){ System.out.println("Entered number "+p+" is a prime number."); } } } <pre>

**Output**

Enter a number greater than 2 which you want to check whether that number is prime or not:

139

Entered number 139 is a prime number.

**Check if a number is Armstron or not.**

Note- A number is armstrong if the sum of the cubes of digit of number is equal to the number.

ex- 407 = 4*4*4 + 0*0*0 + 7*7*7

</pre> 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."); } } } <pre>

**output**

Enter a number which you want to check whether that is armstrong or not:

407

Number 407 is an armstrong number.

Note- Floyd Triangle is like

1

2 3

4 5 6

7 8 9 10

————

Code-

</pre> import java.util.Scanner; public class FloydTriangle{ public static void main(String[] args){ Scanner in = new Scanner(System.in); System.out.println("Enter the number of rows which you want in your Floyd Triangle: "); int r = in.nextInt(); int n=0; for(int i=0; i<r; i++){ for(int j=0; j<=i; j++){ System.out.print(++n+" "); } System.out.println(); } } } <pre>

**Output**

Enter the number of rows which you want in your Floyd Triangle:

5

1

2 3

4 5 6

7 8 9 10

11 12 13 14 15

**Plaindrome of String or reverse a String.**

</pre> import java.util.Scanner; public class PalindromeString{ public static void main(String[] args){ Scanner in = new Scanner(System.in); System.out.println("Enter the string which you want to check whether that is palindrome or not: "); String s = in.next(); String r = ""; for(int i=s.length()-1; i>=0; i--){ r = r+s.charAt(i); } System.out.println("Reverse of entered string "+s+" is "+r); if(r.equals(s)){ System.out.println("String "+s+" is palindrome."); }else{ System.out.println("String "+s+" is not palindrome."); } } } <pre>

**Output-**

Enter the string which you want to check whether that is palindrome or not:

selenium

Reverse of entered string selenium is muineles

String selenium is not palindrome.

</pre> import java.util.Arrays; import java.util.Scanner; public class BinarySearch{ public static void main(String[] args){ Scanner in = new Scanner(System.in); System.out.println("Enter the size of the array which should be greater than zero else it will throw InputMismatchException : "); int size = in.nextInt(); int[] array = new int[size]; System.out.println("Enter the elements of the array: "); for(int i=0; i<size; i++){ array[i] = in.nextInt(); } System.out.println("Enter the search element: "); int s = in.nextInt(); Arrays.sort(array); //binary search will work on sorted array only so sort first int first, last, middle; first=0; last = size-1; middle = (first+last)/2; int i=0; for(; i<size; i++){ if(s>array[middle]){ first = middle+1; }else if(s<array[middle]){ last = middle-1; }else{ printArray(array); System.out.println("Element "+s+" found in the array."); break; } middle= (first+last)/2; } if(i==size){ printArray(array); System.out.println("Element "+s+" is not found in the array"); } } public static void printArray(int[] a){ System.out.println("Array of elements: "); System.out.print("{"); for(int i:a){ System.out.print(i+","); } System.out.println("}"); } }

</pre> package SeleniumMakeItEasy; import org.apache.commons.lang3.ArrayUtils; public class BubbleSort{ public static void main(String[] args){ int[] a = {2,3,2,5,3,3,6,1,2,5}; int l = a.length; for(int i=0;i<l; i++){ for(int j=0; j<l-1; j++){ if(a[j]>a[j+1]){ a[j] = a[j] + a[j+1]; a[j+1] = a[j] - a[j+1]; a[j] = a[j] - a[j+1]; }else if(a[j]==a[j+1]){ a = ArrayUtils.remove(a,j); l = a.length; } } } for(int s: a){ System.out.println(s); } } } <pre>

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