java list remove if duplicates code example

Example 1: how to remove duplicates from an array java

// Must sort arrays first --> Arrays.sort(arrayName)
public class RemoveDuplicateInArrayExample{  
public static int removeDuplicateElements(int arr[], int n){  
        if (n==0 || n==1){  
            return n;  
        }  
        int[] temp = new int[n];  
        int j = 0;  
        for (int i=0; i<n-1; i++){  
            if (arr[i] != arr[i+1]){  
                temp[j++] = arr[i];  
            }  
         }  
        temp[j++] = arr[n-1];     
        // Changing original array  
        for (int i=0; i<j; i++){  
            arr[i] = temp[i];  
        }  
        return j;  
    }  
       
    public static void main (String[] args) {  
        int arr[] = {10,20,20,30,30,40,50,50};  
        int length = arr.length;  
        length = removeDuplicateElements(arr, length);  
        //printing array elements  
        for (int i=0; i<length; i++)  
           System.out.print(arr[i]+" ");  
    }  
}

Example 2: array remove duplicate in java

List<Integer>numbers = Arrays.asList(1,2,2,2,3,5);
System.out.println(numbers);

Set<Integer> hashSet = new LinkedHashSet(numbers);
ArrayList<Integer> removedDuplicates = new ArrayList(hashSet);
System.out.println(removedDuplicates);

Example 3: compare two lists and remove duplicates java

listA.removeAll(new HashSet(listB));