public class Solution {    public int threeSumClosest(int[] nums, int target) {        if (nums == null || nums.length < 3) {            return Integer.MAX_VALUE;        }        Arrays.sort(nums);        int min = Integer.MAX_VALUE/2;//otherwise it will overflow for (min - target); for (int i = 0; i < nums.length; i++) {            int left = i + 1;            int right = nums.length-1;            while (left < right) {                int sum = nums[i] + nums[left] + nums[right];                if (sum == target) {                    return target;                } else if (sum < target) {                    left++;                } else {                    right--;                }                min = Math.abs(sum - target) < Math.abs(min - target) ? sum : min;            }        }        return min;    }}

注意红字部分！，min 开始应该赋值为Integer.MAX_VALUE/2 否则后面的表达式（min - target）如果target为负数会溢出overflow