Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Physics
Chemistry
Biology
Mathematics
English
Economics
Psychology
Social Studies
Fashion Studies
Legal Studies
- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who
How to detect duplicate values in primitive Java array?
To detect the duplicate values in an array you need to compare each element of the array to all the remaining elements, in case of a match you got your duplicate element.
One solution to do so you need to use two loops (nested) where the inner loop starts with i+1 (where i is the variable of outer loop) to avoid repetitions in comparison.
Example
import java.util.Arrays;
import java.util.Scanner;
public class DetectDuplcate {
public static void main(String args[]) {
Scanner sc = new Scanner(System.in);
System.out.println("Enter the size of the array that is to be created::");
int size = sc.nextInt();
int[] myArray = new int[size];
System.out.println("Enter the elements of the array ::");
for(int i=0; i<size; i++) {
myArray[i] = sc.nextInt();
}
System.out.println("The array created is ::"+Arrays.toString(myArray));
System.out.println("indices of the duplicate elements :: ");
for(int i=0; i<myArray.length; i++) {
for (int j=i+1; j<myArray.length; j++) {
if(myArray[i] == myArray[j]) {
System.out.println(j);
}
}
}
}
}Output
Enter the size of the array that is to be created :: 6 Enter the elements of the array :: 87 52 87 63 41 63 The array created is :: [87, 52, 87, 63, 41, 63] indices of the duplicate elements :: 2 5
Solution 2: In addition to this we have a more reliable solution:
The interface set does not allow duplicate elements, therefore, create a set object and try to add each element to it using the add() method in case of repetition of elements this method returns false:
Example
import java.util.Arrays;
import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;
public class DetectDuplcateUsingSet {
public static void main(String args[]) {
Scanner sc = new Scanner(System.in);
System.out.println("Enter the size of the array that is to be created::");
int size = sc.nextInt();
int[] myArray = new int[size];
System.out.println("Enter the elements of the array ::");
for(int i=0; i<size; i++) {
myArray[i] = sc.nextInt();
}
System.out.println("The array created is ::"+Arrays.toString(myArray));
System.out.println("indices of duplicate elements in the array are elements::");
Set set = new HashSet();
for(int i=0; i<myArray.length; i++) {
if(!set.add(myArray[i])) {
System.out.println(i);
}
}
}
}Output
Enter the size of the array that is to be created :: 5 Enter the elements of the array :: 78 56 23 78 45 The array created is :: [78, 56, 23, 78, 45] indices of duplicate elements in the array are elements:: 3
Updated on: 19-Dec-2019
1K+ Views
Advertisements