反转单链表

ListNode是单链表节点的数据结构，实现见如下代码：
package List;

/**
 * Created by Administrator on 2015/10/10.
 */
public class ListNode {
    //节点的值
    private char data;
    //节点的后续节点
    private ListNode next;

    public ListNode(char data, ListNode next) {
        this.data = data;
        this.next = next;
    }
    public ListNode(ListNode next){
        this.next=next;
    }

    public char getData() {
        return data;
    }

    public void setData(char data) {
        this.data = data;
    }

    public ListNode getNext() {
        return next;
    }

    public void setNext(ListNode next) {
        this.next = next;
    }
}
那么对于链表的反转操作及其测试用例如下：

package List;

/**
 * Created by Administrator on 2015/10/10.
 */
public class NodeUtil {
    public static void printList(ListNode head){
        if(head.getNext()==null){
            System.out.println("此链表为空！");
        }else{
           ListNode p=head.getNext();
           while (p.getNext()!=null){
               System.out.print(p.getData()+"->");
               p=p.getNext();
           }
        System.out.print(p.getData());
        }

    }
    //反转链表
    public static ListNode reverseLinkedList(ListNode head){
        ListNode p=head.getNext();
        ListNode q=p.getNext();
        p.setNext(null);
        while (q.getNext()!=null){
            ListNode nextQ=q.getNext();
            q.setNext(p);
            p=q;
            q=nextQ;
        }
        q.setNext(p);
        ListNode root=new ListNode(q);
        return root;
    }
    //测试
    public static void main(String[] args){
        ListNode D=new ListNode('D',null);
        ListNode C=new ListNode('C',D);
        ListNode B=new ListNode('B',C);
        ListNode A=new ListNode('A',B);
        ListNode head=new ListNode(A);
        System.out.println("反转链表之前");
        printList(head);
        System.out.println();
        System.out.println("反转链表之后");
        ListNode root=reverseLinkedList(head);
        printList(root);
    }
}