Two Sum III - Data structure design leetcode

Design and implement a TwoSum class. It should support the following operations: add and find.

add - Add the number to an internal data structure.
find - Find if there exists any pair of numbers which sum is equal to the value.

For example,

add(1); add(3); add(5);
find(4) -> true
find(7) -> false

public class TwoSum {
    private HashMap<Integer, Integer> map = new HashMap<Integer, Integer>();
    // Add the number to an internal data structure.
 public void add(int number) {
     if (map.containsKey(number)) {
         map.put(number, map.get(number) + 1);
     } else {
         map.put(number, 1);
     }
 }

    // Find if there exists any pair of numbers which sum is equal to the value.
 public boolean find(int value) {
     for (Integer s : map.keySet()) {
         int tem = value - s;
         if (tem == s && map.get(tem) > 1) {
             return true;
         } 
         if ( tem != s && map.containsKey(tem)) {
                 return true;
         }
     }
     return false;
 }
}