how to remove duplicates from an array java

1public static void main(String[] args) {
2
3        String result = removeDup("AAABBBCCC");
4        System.out.println(result); // ABC
5
6public static  String  removeDup( String  str) {
7        String result = "";
8        for (int i = 0; i < str.length(); i++)
9            if (!result.contains("" + str.charAt(i)))
10                result += "" + str.charAt(i);
11        return result;
12    }
13}

1// Must sort arrays first --> Arrays.sort(arrayName)
2public class RemoveDuplicateInArrayExample{  
3public static int removeDuplicateElements(int arr[], int n){  
4        if (n==0 || n==1){  
5            return n;  
6        }  
7        int[] temp = new int[n];  
8        int j = 0;  
9        for (int i=0; i<n-1; i++){  
10            if (arr[i] != arr[i+1]){  
11                temp[j++] = arr[i];  
12            }  
13         }  
14        temp[j++] = arr[n-1];     
15        // Changing original array  
16        for (int i=0; i<j; i++){  
17            arr[i] = temp[i];  
18        }  
19        return j;  
20    }  
21       
22    public static void main (String[] args) {  
23        int arr[] = {10,20,20,30,30,40,50,50};  
24        int length = arr.length;  
25        length = removeDuplicateElements(arr, length);  
26        //printing array elements  
27        for (int i=0; i<length; i++)  
28           System.out.print(arr[i]+" ");  
29    }  
30} 

1public class RemoveDuplicateElementDemo 
2{
3   public static int removeDuplicate(int[] arrNumbers, int num)
4   {  
5      if(num == 0 || num == 1)
6      {  
7         return num;  
8      }  
9      int[] arrTemporary = new int[num];  
10      int b = 0;  
11      for(int a = 0; a < num - 1; a++)
12      {  
13         if(arrNumbers[a] != arrNumbers[a + 1])
14         {  
15            arrTemporary[b++] = arrNumbers[a];  
16         }  
17      }  
18      arrTemporary[b++] = arrNumbers[num - 1]; 
19      for(int a = 0; a < b; a++)
20      {  
21         arrNumbers[a] = arrTemporary[a];  
22      }  
23      return b;  
24   }
25   public static void main(String[] args) 
26   {
27      int[] arrInput = {1, 2, 3, 3, 4, 5, 5, 6, 7, 8};  
28      int len = arrInput.length;  
29      len = removeDuplicate(arrInput, len);  
30      // printing elements
31      for(int a = 0; a < len; a++)
32      {
33         System.out.print(arrInput[a] + " ");
34      }
35   }
36}