java 使用心得

String.split()
Once you want to plit '.', you have to use it like below:
String.split("\\.")

 PriorityQueue que= new PriorityQueue(len,new Comparator(){
                public int compare(ListNode a,ListNode b){
                if(a.val < b.val)
                    return -1;
                if(a.val > b.val)
                    return 1;
                return 0;
                }
        }); 

How to sort an ArrayList.
Collections.sort(arrays, new Comparator(){
     public int compare(a, b){
     }
})