java check if there are duplicates in list code example

Example 1: java array check duplicates

duplicates = false;

for(i = 0; i < zipcodeList.length; i++) {
	for(j = i + 1; k < zipcodeList.length; j++) {
  		if(j != i && zipcodeList[j] == zipcodeList[i]) {
   	  		duplicates = true;
		}
	}
}

Example 2: java find duplicate element in list

public static Set<String> findDuplicates(List<String> listContainingDuplicates) {
 
		final Set<String> setToReturn = new HashSet<String>();
		final Set<String> set1 = new HashSet<String>();
 
		for (String yourInt : listContainingDuplicates) {
			if (!set1.add(yourInt)) {
				setToReturn.add(yourInt);
			}
		}
		return setToReturn;
	}