Java Array Programs

Java Array Programs: We will be discussing Java Array Programs. These programs are some of the most asked questions in interviews and coding exams. Practicing these Array programs in Java languages will help you understand various array concepts.

Try solving the below array programs by yourself, and then check the solution. So get started with the below list of array programs now to improve your skills.

Post Type:Java Programs For Beginners
Published On:www.softwaretestingo.com
Applicable For:Freshers & Experience
Get Updates:Join Our Telegram Group

Java Array Programs

Here is the list of frequently asked Java Array Programs:

Some Basic Java Array Programs For Freshers Automation Testers

package com.java.ArrayEx;
public class ArrayPGM1 {
   public static void main(String[] args) 
   {
      int [] a=new int[3];
      a[0]=10;
      a[1]=20;
      a[2]=30;
      System.out.println(a[0]);
      System.out.println(a[1]);
      System.out.println(a[2]);
      System.out.println("Array of length=" + a.length);
   }
}

Result:

10
20
30
Array of length=3

Another Array Program:

package com.java.ArrayEx;
public class ArrayPGM2 {
   public static void main(String[] args) 
   {
      String [] s={"Software","Testing","Blog"};
      System.out.println(s[0]);
      System.out.println(s[1]);
      System.out.println(s[2]);
      System.out.println("Array of length=" + s.length);
   }
}

Result:

Software
Testing
Blog
Array of length=3

Another Program Of Array:

package com.java.ArrayEx;
public class ArrayPGM3 {
   public static void main(String[] args) 
   {
      int[] a=new int[5];
      a[0]=1;
      a[1]=2;
      a[2]=3;
      a[3]=4;
      a[4]=5;
      for(int i=0;i<a.length;i++)
      {
         System.out.println(a[i]);
      }
   }
}

Result:

1
2
3
4
5

Write a Program to Compare Two Array In Java With Example?

package com.java.Softwaretestingblog;
import java.util.Arrays;
public class CompareTwoArray {

   public static void main(String[] args) {
      // TODO Auto-generated method stub
      int arr1[] = {1, 2, 3};
      int arr2[] = {1, 2, 3};
      if (Arrays.equals(arr1, arr2))
         System.out.println("Same");
      else
         System.out.println("Not same");

   }
}

Final Results:

Same

Write a Program to Get Second Highest Element In an Array:

package com.java.ArrayEx;
public class Array2ndLargestvalue {
   public static void main(String[] args) 
   {
      int numbers[] = { 47, 3, 37, 12, 46, 5, 64, 21 };
      //System.out.println(numbers.length);
      int highest = 0;
      int second_highest = 0;
      for (int n : numbers) {
         if (highest < n) {
            second_highest = highest;
            highest = n;
         } else if (second_highest < n) {
            second_highest = n;
         }
      }
      System.out.println("First Max Number: " + highest);
      System.out.println("Second Max Number: " + second_highest);
   }
}

The Final Output:

First Max Number: 64
Second Max Number: 47

How to Copy Specific Array Values into String In Java With Example?

package com.java.Softwaretestingblog;
public class Copy_Specific_Array_Values 
{
   public static void main(String[] args) 
{
      // TODO Auto-generated method stub
      char ch[] = {'S','o','f','t','w','a','r','e','T','e','s','t','i','n','g','B','l','o','g'}; 
      /** * We can copy a char array to a string by using * copyValueOf() method. */ 
      String chStr = String.copyValueOf(ch); 
      System.out.println("Original Array Values :- "+chStr); 
      /** * We can also copy only range of charactors in a * char array by copyValueOf() method. */ 
      String subStr = String.copyValueOf(ch,8,7); 
      System.out.println("Substring From The Original String :-"+subStr);
   }
}

Output:

Original Array Values :- SoftwareTestingBlog
Substring From The Original String :-Testing

Write a Program For Simple Java Array Program Example?

package com.java.Softwaretestingblog;
public class ArrayEx1 {
   public static void main(String[] args) {
      // TODO Auto-generated method stub
      int i=10;
      for(i=10;i>0;i--)
      {
         for(int j=1;j<=10;j++)
         {
            if((i+j)==11)
            {
               int k=i*j;
               System.out.println(i + "*" + j+"="+k );
            }
         }
      }
   }
}

Final Result:

10*1=10
9*2=18
8*3=24
7*4=28
6*5=30
5*6=30
4*7=28
3*8=24
2*9=18
1*10=10

Write a Program to Print Default Array Value Program In Java?

package com.java.Softwaretestingblog;
public class DefaultArrayValue {
   public static void main(String[] args) {
      // TODO Auto-generated method stub
      System.out.println("String array default values:");
      String str[] = new String[5];
      for (String s : str)
         System.out.print(s + " ");

      System.out.println("\n\nInteger array default values:");
      int num[] = new int[5];
      for (int val : num)
         System.out.print(val + " ");

      System.out.println("\n\nDouble array default values:");
      double dnum[] = new double[5];
      for (double val : dnum)
         System.out.print(val + " ");

      System.out.println("\n\nBoolean array default values:");
      boolean bnum[] = new boolean[5];
      for (boolean val : bnum)
         System.out.print(val + " ");

      System.out.println("\n\nReference Array default values:");
      DefaultArrayValue ademo[] = new DefaultArrayValue[5];
      for (DefaultArrayValue val : ademo)
         System.out.print(val + " ");

   }
}

Final Results:

String array default values: null null null null null

Integer array default values: 0 0 0 0 0

Double array default values: 0.0 0.0 0.0 0.0 0.0

Boolean array default values: false false false false false

Reference Array default values: null null null null null

Write a Program to Find Find Largest & Smallest Number in an Array?

package com.java.Softwaretestingblog;
public class FindLargestSmallestNumber {
   public static void main(String[] args) {
      // TODO Auto-generated method stub
      //array of 10 numbers
      int numbers[] = new int[]{32,43,53,54,32,65,63,98,43,23};
      //assign first element of an array to largest and smallest
      int smallest = numbers[0];
      int largetst = numbers[0];
      for(int i=1; i< numbers.length; i++)
      {
         if(numbers[i] > largetst)
            largetst = numbers[i];
         else if (numbers[i] < smallest)
            smallest = numbers[i];
      }
      System.out.println("Largest Number is : " + largetst);
      System.out.println("Smallest Number is : " + smallest);
   }
}

Output:

Largest Number is : 98
Smallest Number is : 23

Write a Program to Find Out No Of Occurrence Of a Character?

package com.java.Softwaretestingblog;
public class FoundNoOfOccurance {
   public static void main(String[] args) {
      // TODO Auto-generated method stub
      String s="i am monoj good boy";
      char c='o';
      int total_size=s.length();
      int replace_sie=s.replace("o", "").length();
      System.out.println(total_size +"\t"+replace_sie);
      int count=s.length()-s.replace("o", "").length();
      System.out.println("Number of occurances of 'a' is= "+ count);
   }
}

Output:

19 14
Number of occurrence of 'a' is= 5

Write a Program to Copy Elements From One Array2Array

Array2Array Program 1:

package com.java.ArrayEx;
public class ArrayCopy {
   public static void main(String[] args)
   {
      char  a[]={'a','b','c','d','e','f'};
      char [] b=new char[3];
      System.arraycopy(a, 1, b, 0,3);
      System.out.println("New String b=" + new String(b));
   }
}

Let’s Execute the above Array

Execution Result:

New String b=bcd

Program 2:

package com.java.Softwaretestingblog;
public class ArrayCopy {
   public static void main(String[] args) {
   // TODO Auto-generated method stub
   char ch[] = {'S','O','F','T','W','A','R','E','T','E','S','T','I','N','G','B','L','O','G'};
        String chStr = String.copyValueOf(ch);
        System.out.println(chStr);
        String subStr = String.copyValueOf(ch,8,7);
        System.out.println(subStr);
   }
}

Execution Result:

SOFTWARETESTINGBLOG
TESTING

How to Verify Two Arrays Without Using Function to Verify Equal Or Not?

package com.softwaretestingblog.programs;
public class VerifyTwoArrayWithoutFunction {
   public static void main(String[] args) {
      int[] arrayOne = {2, 5, 1, 7, 4};        
      int[] arrayTwo = {2, 5, 1, 7, 4};         
      boolean equalOrNot = true;

      if(arrayOne.length == arrayTwo.length)
      {
         for (int i = 0; i < arrayOne.length; i++)
         {
            if(arrayOne[i] != arrayTwo[i])
            {
               equalOrNot = false;
            }
         }
      }
      else
      {
         equalOrNot = false;
      }

      if (equalOrNot)
      {
         System.out.println("Two Arrays Are Equal");
      }
      else
      {
         System.out.println("Two Arrays Are Not equal");
      }
   }
}

Output:

Two Arrays Are Equal

How to Find Common Element Between Two Arrays In Java?

package com.softwaretestingblog.programs;
import java.util.HashSet;
public class FindCommonElementFrom2Array {
   public static void main(String[] args) {
      String[] s1 = {"ONE", "TWO", "THREE", "FOUR", "FIVE", "FOUR"};
      String[] s2 = {"THREE", "FOUR", "FIVE", "SIX", "SEVEN", "FOUR"};

      HashSet<String> set = new HashSet<String>(); 
      for (int i = 0; i < s1.length; i++)
      {
         for (int j = 0; j < s2.length; j++)
         {
            if(s1[i].equals(s2[j]))
            {
               set.add(s1[i]);
            }
         }
      } 
      System.out.println(set);     //OUTPUT : [THREE, FOUR, FIVE]
   }
}

Output:

[FIVE, FOUR, THREE]

How to Find Two Max Numbers From an Array In Java?

package com.softwaretestingblog.programs;
public class FindTwoMaxNumbers {
   public void findTwoMaxNumbers(int[] array){
      int maxOne = 0;
      int maxTwo = 0;
      for(int i:array)
      {
         if(maxOne < i)
         {
            maxTwo = maxOne;
            maxOne =i;
         }
         else if(maxTwo < i)
         {
            maxTwo = i;
         }
      }

      System.out.println("First Maximum Number: "+maxOne);
      System.out.println("Second Maximum Number: "+maxTwo);
   }
   public static void main(String a[]){
      int num[] = {4,23,67,1,76,1,98,13};
      FindTwoMaxNumbers obj = new FindTwoMaxNumbers();
      obj.findTwoMaxNumbers(num);
      //obj.findTwoMaxNumbers(new int[]{4,5,6,90,1});
   }
}

Output:

First Maximum Number: 98
Second Maximum Number: 76

Duplicate Array Elements Java Program

How to Find Out Duplicate Array Elements Using Java Example Program?

package com.hcl.tmobile.submitservicechange;
public class Find_Duplicate_Element_Array
{
   public static void main(String[] args) 
   {
      String[] strArray = {"abc", "def", "mno", "xyz", "pqr", "xyz", "def"};

      for (int i = 0; i < strArray.length-1; i++)
      {
         for (int j = i+1; j < strArray.length; j++)
         {
            if( (strArray[i].equals(strArray[j])) && (i != j) )
            {
               System.out.println("Duplicate Element is : "+strArray[j]);
            }
         }
      }
   }
}

How to Find Duplicate Element In An Array Using Collection In Java?

In this post, we are going to discuss how you can find the duplicate number or character, or elements of an inputted string.

package com.hcl.tmobile.submitservicechange;
import java.util.HashSet;
public class FindDuplicateElement 
{
   public static void main(String[] args) 
   {
      String[] strArray = {"abc", "def", "mno", "xyz", "pqr", "xyz", "def"};
      HashSet<String> set = new HashSet<String>(); 
      for (String arrayElement : strArray)
      {
         if(!set.add(arrayElement))
         {
            System.out.println("Duplicate Element is : "+arrayElement);
         }
      }
   }
}

Find the Missing and Duplicate Numbers in the Array

Here are the different methods of finding the missing and duplicate numbers between two arrays. If you want to check more Java Programs, you can follow this link.

Find the Missing and Duplicate Numbers in the Array

  1. UsingTemp Variable
package com.softwaretestingo.interviewprograms;
public class FindMissingDuplicateNumberEX1 
{
	static void printTwoElements(int[] arr, int n)
    {
        int[] temp = new int[n]; // Creating temp array of size n
        
        // with initial values as 0.
        int repeatingNumber = -1;
        int missingNumber = -1;
 
        for (int i = 0; i < n; i++) 
        {
            temp[arr[i] - 1]++;
            if (temp[arr[i] - 1] > 1) 
            {
                repeatingNumber = arr[i];
            }
        }
        for (int i = 0; i < n; i++) 
        {
            if (temp[i] == 0) 
            {
                missingNumber = i + 1;
                break;
            }
        }
 
        System.out.println("The repeating number is " + repeatingNumber + ".");
        System.out.println("The missing number is " + missingNumber + ".");
    }

	public static void main(String[] args) 
	{
		int[] arr = { 7, 3, 4, 5, 5, 6, 2 };
        int n = arr.length;
        printTwoElements(arr, n);
	}
}

2. Next Way

package com.softwaretestingo.interviewprograms;

public class FindMissingDuplicateNumberEX2 
{
	static void printTwoElements(int arr[], int size)
    {
        int i;
        System.out.print("The repeating element is ");
 
        for (i = 0; i < size; i++) 
        {
            int abs_val = Math.abs(arr[i]);
            if (arr[abs_val - 1] > 0)
                arr[abs_val - 1] = -arr[abs_val - 1];
            else
                System.out.println(abs_val);
        }
 
        System.out.print("and the missing element is ");
        for (i = 0; i < size; i++) 
        {
            if (arr[i] > 0)
                System.out.println(i + 1);
        }
    }

	public static void main(String[] args) 
	{
		int arr[] = { 7, 3, 4, 5, 5, 6, 2 };
        int n = arr.length;
        printTwoElements(arr, n);
	}
}

3. Using Map

package com.softwaretestingo.interviewprograms;
import java.util.HashMap;
import java.util.Map;
public class FindMissingDuplicateNumberEX3 
{
	public static void main(String[] args) 
	{
		int[] arr = { 4, 3, 6, 2, 1, 1, 2 };

		Map<Integer, Boolean> numberMap = new HashMap<>();

		int max = arr.length;
		
		for (Integer i : arr) 
		{

			if (numberMap.get(i) == null) 
			{
				numberMap.put(i, true);
			}
			else 
			{
				System.out.println("Repeating = " + i);
			}
		}
		for (int i = 1; i <= max; i++)
		{
			if (numberMap.get(i) == null) 
			{
				System.out.println("Missing = " + i);
			}
		}
	}
}

Now We will try to Find the missing number between two Arrays.

package com.softwaretestingo.interviewprograms;
import java.util.Arrays;
public class FindMissingNumberBetween2ArrayEx 
{
	private static int missingNumber(int[] arr1, int arr2[]) 
	{
		 
        int missingNumber = arr1[0];
        for (int index = 1; index < arr1.length; index++) 
        {
            missingNumber ^= arr1[index];
        }
 
        for (int index = 0; index < arr2.length; index++) 
        {
            missingNumber ^= arr2[index];
        }
        return missingNumber;
    }
	public static void main(String[] args) 
	{
		int array1[] = { 1, 2, 3, 4, 5 };
        int array2[] = { 1, 2, 4, 5 };
 
        String sArr1 = Arrays.toString(array1);
        String sArr2 = Arrays.toString(array2);
 
        System.out.printf("1. Missing number in array1 & array2 is:", sArr1, sArr2);
        int missingNumber = missingNumber(array1, array2);
        System.out.printf(" %d", missingNumber);
 
        array1 = new int[] { 10, 20, 30, 40 };
        array2 = new int[] { 20, 30, 40,  };
 
        sArr1 = Arrays.toString(array1);
        sArr2 = Arrays.toString(array2);
 
        System.out.printf("\n2. Missing number in array1 & array2 is:", sArr1, sArr2);
        missingNumber = missingNumber(array1, array2);
        System.out.printf(" %d", missingNumber);
	}
}

Conclusion:

We have compiled a list of the top Java Array Programs interview questions with answers to help freshers prepare for their interviews. The key to success in the Java interview is going through as many questions as you can.

If during the interview if you face any other Java Array Programs then you can update us in the comment section and we will try to update those in our blog post.

I love open-source technologies and am very passionate about software development. I like to share my knowledge with others, especially on technology that's why I have given all the examples as simple as possible to understand for beginners. All the code posted on my blog is developed, compiled, and tested in my development environment. If you find any mistakes or bugs, Please drop an email to softwaretestingo.com@gmail.com, or You can join me on Linkedin.

Leave a Comment