Find a pair of elements from an array whose sum equals a given number

Question

Given array of n integers and given a number X, find all the unique pairs of elements (a,b), whose summation is equal to X.

The following is my solution, it is O(nLo

Answer 1

One Solution can be this, but not optimul (The complexity of this code is O(n^2)):

public class FindPairsEqualToSum {

private static int inputSum = 0;

public static List findPairsForSum(int[] inputArray, int sum) {
    List list = new ArrayList();
    List inputList = new ArrayList();
    for (int i : inputArray) {
        inputList.add(i);
    }
    for (int i : inputArray) {
        int tempInt = sum - i;
        if (inputList.contains(tempInt)) {
            String pair = String.valueOf(i + ", " + tempInt);
            list.add(pair);
        }
    }
    return list;
   }
}