Permutations

 1    public List<List<Integer>> permute(int[] nums) {
 2         
 3             List<List<Integer>> re = null;
 4             List<List<Integer>> bf = new ArrayList<List<Integer>>();
 5             Iterator<List<Integer>> it = null;
 6             List<Integer> list =null;
 7             List<Integer> addList =null;
 8 
 9             if( nums == null || nums.length <= 0 )
10                     return bf;
11 
12             list = new ArrayList<Integer>();    
13             list.add(nums[0]);
14             bf.add(list);
15             re = bf;
16             for(int i = 1; i < nums.length; i++)
17             {
18 
19                 it = bf.iterator();
20                 re = new ArrayList<List<Integer>>();
21                 while(it.hasNext())
22                 {
23                     list = it.next();
24                     for(int j = 0 ; j <= list.size(); j++ )
25                     {
26                         addList = new ArrayList<Integer>(list);
27                         addList.add(j,nums[i]);
28                         re.add(addList);
29                     }
30                 }
31                 bf = re;
32             }
33             return re;
34     
35     }