最近学java链表有一段程序搞不懂!!希望各位大帮帮忙!!

class StudLinkedList implements StudOPeration{
    private StuNode head;
    private int count;
    StudLinkedList(){
        head=null;
        count=0;
        }    
    public void add(StuNode node){
        StuNode current=head,pre=head;
        if(head==null)
          head=node;
        else{
            while(current!=null)
                if(current.studentNo>node.studentNo)
                 break;
                 else{
                 pre=current;
                 current=current.getNext();
              }
              if(current.next==null)
                  pre.next=node;
              else if(current==head){
                  head=node;
                  node.next=current;
              }
              else{ 
                  pre.next=node;
                  node.next=current;
              }
            }
    
            count++;
        }
        
        
        谢谢啦!!!
        
        最好注解写得全一点!!