//class Link{ private Node root;//the head node 

  public void addNode(String data){     Node newNode = new Node(data);       if(this.root == null){          this.root = newNode;     }else{            this.root.add(newNode);//method add() is defined in class Node.       } } public void printNode(){      if(this.root != null){           this.root.print();        } } public boolean contains(String name){     return this.root.search(name);    } public void deleteNode(String data){      if(this.contains(data)){          if(this.root.data.equals(data)){              this.root = this.root.next;          }else{                this.root.next.delete(root, data);            }     } } //inner class Node，将节点进行封装，方便以后的调用，而不用由用户手工去处理各个节点的关系。   class Node{       private String data;      private Node next;        public Node(String data){         this.data = data;        }     public void add(Node newNode){//add node but no data          if(this.next == null){              this.next = newNode;         }else{                this.next.add(newNode);//迭代的方法            }     }     public void print(){//迭代输出            System.out.println(this.data);            if(this.next != null){               this.next.print();            }     }     public boolean search(String data){           if(data.equals(this.data)){               return true;          }else{                if(this.next != null){                   return this.next.search(data);                }else{                        return false;             }         }     }     public void delete(Node previous, String data){//可以把previous理解为头指针            if(data.equals(this.data)){               previous.next = this.next;           }else{                if(this.next != null){                   this.next.delete(this, data);             }         }     } }

}public class Test12_1 {  public static void main(String args[]){       Link l = new Link();     l.addNode("A");     l.addNode("B");     l.addNode("C");     System.out.println("=====================before delete================");      l.printNode();        l.deleteNode("B");      System.out.println("==================deleted==================");      l.printNode();        System.out.println();     System.out.println("searse node: "+l.contains("A")); }}