leetcode--3Sum Closest

Given an array S of n integers, find three integers in S such that the sum is closest to a given number, target. Return the sum of the three integers. You may assume that each input would have exactly one solution.

    For example, given array S = {-1 2 1 -4}, and target = 1.

    The sum that is closest to the target is 2. (-1 + 2 + 1 = 2).

public class Solution {
    public int threeSumClosest(int[] num, int target) {
        int sum = 0, length = num.length;
		if(length > 0) {
			if(length <= 3) {
				for(int i = 0; i < length; ++i)
					sum += num[i];
			}
			else {
				Arrays.sort(num);
				int difference = Integer.MAX_VALUE;
				for(int i = 0; i < length; ++i) {
					int start = i + 1, end = length - 1;					
					while(start < end){
						int temp = num[i] + num[start] + num[end];
						if(temp == target) 
							return target;
						else {
							if(difference > Math.abs((target - temp))){
								sum = temp;
								difference = Math.abs((target - temp));
							}
							if(temp < target)
								++start;
							else
								--end;
						}						
					}
				}
			}
		}
		return sum;    
    }
}