Java-Code

public class MainClass {

	public static void main(String[] args) {
		
		int []arr1 =  { 1, 2, 3, 1, 2 } ;//=> Summe = 3

		int []arr2 = { 1, 2, 3, 4, 5 };// => Summe = 15

		int []arr3 = { 1, 2, 3, 3, 2, 1 };// => Summe = 0
		
		
		System.out.println(sum(arr1));
		System.out.println(sum(arr2));
		System.out.println(sum(arr3));
		
					
		}
	
	public static int sum(int[] arr) {
		int s=0;
		for (int i = 0; i < arr.length; i++) {
			
			for (int j = i+1; j < arr.length; j++) {
				
				if (arr[i]==arr[j]) {
					arr[i]=0;
					arr[j]=0;
					
				}
			}
		}
		
		for (int i = 0; i < arr.length; i++) {
			s+= arr[i];
		}
		return s;
	}
		
	}

Java-Code

public static int rechnen(int[]as)
	{
		int zws=0;
		for(int i=0;i<as.length;i++)
		{
			zws+=as[i];
			
			for(int a=0;a<as.length;a++)
			{
				if(as[i]==as[a] && a!=i)
				{
					zws-=as[i];
					break;
					
				}
			}
		}
		return zws;
	}
}

Java-Code

	
public static int sumArray(int[] arr1,int[] arr2, int[] arr3) {
	ArrayList<Integer> sumArray = new ArrayList<>();
	int summe = 0;
	for(int i = 0, j = 0, temp =0;i<arr1.length || j<arr2.length || temp<arr3.length ;) {
		if(i<arr1.length && !sumArray.contains(arr1[i])) {
			sumArray.add(arr1[i]);
			i++;
		}
		if(j<arr2.length && !sumArray.contains(arr2[j])) {
			sumArray.add(arr2[j]);
			j++;
		}
		if(temp<arr1.length && !sumArray.contains(arr3[temp])) {
			sumArray.add(arr3[temp]);
			temp++;
			}
	}
	for(int i : sumArray) {
		summe+=i;
	}
	return summe;
}