Java实现链表的增删改查

1、在另一个类里定义结点和构造器
class Node {
Node next;
int data;
public Node(){}
public Node(int data) {this.data = data; }
public Node(int data,Node next){
this.next=next;
this.data=data;
}
}
2、实现增删改查
public class ListNode {
public boolean add(int i, Node node,Node head) {
int length=0;
Node p1=head;
while(p1!=null){
p1=p1.next;
length++;
}
int j=1;
while(j<i-1){
if(headnull)
return false;
head=head.next;
j++;
}
if(ilength+1 ){
head.next=node;
}
else if(i>length+1||i==0 )
return false;
else{
node.next=head.next;
head.next=node;
}
return true;
}

public Node delete(int i,Node head) {
    Node node=null;
    int length = 0;
    Node p1 = head;
    while (p1 != null) {
        p1 = p1.next;
        length++;
    }
    if (i == 0){
        return null;
    }
    if(i==1)
    {
        node=head;
        //System.out.println(node.next.data);
        return node;
    }
    int j = 1;
    while (j < i-1) {
        head = head.next;
        j++;
    }
    if (i == length) {
        node=head.next;
        head.next=null;
        return node;
    }
    else {
        node = head.next;
        head.next = node.next;
    }
    //System.out.println(node.data);
    return node;
}
public boolean change(int i,Node node,Node head){
    int length = 0;
    Node p1 = head;
    while (p1 != null) {
        p1 = p1.next;
        length++;
    }
    if(head==null||i>length ||i==0)
    {
        return false;
    }
    else if(i==1){
        node.next=head.next;
        head=node;
        //System.out.println(head.data);
        //System.out.println(node.next.data);
        return true;
    }
    else if(i==length){
        node.next=null;
        head.next=node;
       // System.out.println(head.next.data);
        return true;
    }
    int j = 1;
    while (j < i - 1) {
        head = head.next;
        j++;
    }
        node.next=head.next.next;
        head.next = node;
    //System.out.println(head.next.data);
    //System.out.println(node.next.data);
        return true;
    }

public Node find(int i,Node head) {
    int length = 0;
    Node p1 = head;
    while (p1 != null) {
        p1 = p1.next;
        length++;
    }
    if (i == 0){
        return null;
    }
    if (i == 1) {
        System.out.println(head.data);
        return head;
    }
    if (head != null && i > 1 && i <= length) {
        int j = 1;
        while (j < i) {
            head = head.next;
            j++;
        }
    }
    //System.out.println(head.data);
    return head;
}

public static void main(String[] args){
    Node p4=new Node(4,null);
    Node p3=new Node(3,p4);
    Node p2=new Node(2,p3);
    Node p1=new Node(1,p2);
    Node p5=new Node(5);
    ListNode p=new ListNode();
   // System.out.println(p.add(2,p4,p1));
    //System.out.println(p1.next.next.data);
    System.out.println(p.delete(1,p1).data);
   // System.out.println(p2.next.data);
    //System.out.println(p.change(1,p4,p1));

    //System.out.println(p.find(2,p1));
}

}