Check duplicated value in array

Here i attached a java example to show how to check duplicated value in an array. I show two methods to implement this.

1) Using two for loop to compare each values in array – Line 21

2)Using HashSet to detect duplicated value. – Line 40

Hope help, if you know any other method to compare duplicated value in array, please share it to me.

 

package com.mkyong;

import java.util.Set;
import java.util.HashSet;

public class CheckDuplicate
{
	public static void main(String args[])
	{
		String [] sValue = new String[]{"a","b","c","d","","","e","a"};
		
		if(checkDuplicated_withNormal(sValue))
			System.out.println("Check Normal : Value duplicated! \n");
		if(checkDuplicated_withSet(sValue))
			System.out.println("Check Set : Value duplicated! \n");
		
	}
	
	//check duplicated value
	private static boolean checkDuplicated_withNormal(String[] sValueTemp)
	{
		for (int i = 0; i < sValueTemp.length; i++) {
			String sValueToCheck = sValueTemp[i];
			if(sValueToCheck==null || sValueToCheck.equals(""))continue; //empty ignore
			for (int j = 0; j < sValueTemp.length; j++) {
					if(i==j)continue; //same line ignore
					String sValueToCompare = sValueTemp[j];
					if (sValueToCheck.equals(sValueToCompare)){
							return true;
					}
			}

		}
		return false;
		
	}
	
	//check duplicated value
	private static boolean checkDuplicated_withSet(String[] sValueTemp)
	{
		Set sValueSet = new HashSet();
		for(String tempValueSet : sValueTemp)
		{
			if (sValueSet.contains(tempValueSet))
				return true;
			else
				if(!tempValueSet.equals(""))
					sValueSet.add(tempValueSet);
		}
		return false;
	}
	
	
}



About the Author

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mkyong
Founder of Mkyong.com, love Java and open source stuff. Follow him on Twitter, or befriend him on Facebook or Google Plus. If you like my tutorials, consider make a donation to these charities.

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srreddy
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srreddy

How to remove duplicate values.

int[] arr = {1,1,1,2,3,4,5,6,7,8,8};

Venkat
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Venkat

Very good site

Judy
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Judy

this is a good script

sandrar
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sandrar

Hi! I was surfing and found your blog post… nice! I love your blog. :) Cheers! Sandra. R.