Given an integer array, output all pairs that sum up to a value k

pairsThatSumUpToK

public static List<Pair> pairsThatSumUpToK(int[] a, int k) {
    Arrays.sort(a);
	List<Pair> result = new ArrayList<Pair>();
	int left = 0;
	int right = a.length-1;
	
	while(left < right) {
		int sum = a[left] + a[right];
		if (sum < k) left++;
		else if (sum > k) right--;
		else {
			result.add(new Pair(a[left], a[right]));
			left++;
			right--;
		}
	}
	return result;
}

public class Pair{
  protected int x;
  protected int y;

  public class Pair(int x, int y) {
  	this.x = x;
  	this.y = y;
  } 
}