15. 3Sum Java

import java.util.*;
class Solution {
    public <T extends Comparable<T>> List<List<Integer>> threeSum(int[] nums) {
        List<List<Integer>> output = new ArrayList<List<Integer>>();
        int length = nums.length;
        Arrays.sort(nums);
        int j = 0;
        int k = length-1;
        for (int i = 0; i < length-2; i++){
            j = i + 1;
            k = length-1;
            if (i > 0 && nums[i] == nums[i-1]){continue;}
            if(nums[i]>0){break;}
            while(j<k){
                if (nums[i]+nums[j]+nums[k] == 0){
                    List<Integer> temp = Arrays.asList(nums[i], nums[j], (0-nums[i]-nums[j]));
                    output.add(temp);
                    while (j < k && nums[j] == nums[j+1]){j++;}
                    while (j < k && nums[k] == nums[k-1]){k--;}
                }
                
                if (nums[i]+nums[j]+nums[k] < 0){j++;}
                else{k--;}
            }
        }
    return output;
    }
}