单链表

【节点】

package linkedList;

public class Node {
    int val;
    Node next;
    public Node(int val){
        this.val=val;
        this.next=null;
    }
}

【单链表】

package linkedList;

public class LinkedList {
    Node first;
    Node last;
    
    public LinkedList(int[] array) {
        for (int i = 0; i < array.length; i++) {
            addNodeToLinkedList(array[i]);
        }
    }
    
    public void addNodeToLinkedList(int val) {//创建单链表
        Node newNode=new Node(val);
        if(first==null) {
            first=newNode;
            last=first;
            return;
        }
        last.next=newNode;
        last=last.next;
    }
    
    public void printLinkedList(Node head) {//打印单链表
        Node current=head;
        System.out.print("当前链表节点顺序：");
        while(current!=null) {
            System.out.print("  "+current.val);
            current=current.next;
        }
    }
    
    public void insertFirst(int val) {//新节点插在表头前面
        Node newNode=new Node(val);
        newNode.next=first;
        first=newNode;
    }
    
    public void insertLast(int val) {//新节点插在表尾后面
        Node newNode=new Node(val);
        last.next=newNode;
        last=newNode;
    }
    
    public void insert(int target,int val) {//新节点插在目标值后面 
        Node newNode=new Node(val);
        Node current=first;
        while(current.val!=target) {
            current=current.next;
        }
        Node temp=current.next;
        current.next=newNode;
        newNode.next=temp;
    }
    
    public void search(int val) {//从链表里查询值是否存在
        Node current=first;
        while(current!=null) {
            if(current.val==val) {
                System.out.println("链表里存在  "+current.val);
                return;
            }
            current=current.next;
        }
        if(last.val!=val)
            System.out.println("链表里不存在  "+val);
    }
    
    public void deleteFirst(Node head) {//删除表头
        head=head.next;
    }
    
    public void deleteLast(Node head) {//删除表尾
        Node current=head;
        Node temp=null;
        while(current.next!=null) {
            temp=current;
            current=current.next;
        }
        temp.next=null;
        last=temp;
    }
    
    public void delete(int val) {//删除某值节点
        Node current=first;
        Node temp=null;
        while(current.val!=val) {
            temp=current;
            current=current.next;
        }
        temp.next=current.next;
    }
    
}

【测试】

package linkedList;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Test {

    public static void main(String[] args)throws IOException {
        BufferedReader in=new BufferedReader(new InputStreamReader(System.in));
        int[] array=new int[5];
        System.out.println("请依次输入五个整数:");
        for (int i = 0; i < array.length; i++) {
            array[i]=Integer.parseInt(in.readLine());
        }
        System.out.print("输入五个整数为：");
        for (int i = 0; i < array.length; i++) {
            System.out.print("  "+array[i]);
        }
        System.out.println();
        LinkedList linkedList=new LinkedList(array);
        linkedList.printLinkedList(linkedList.first);
        System.out.println();
        while(true) {
            System.out.print("请输入一个整数作为新插入节点值插在表头前面（输入 -1 退出）：");
            int val=Integer.parseInt(in.readLine());
            if(val==-1) {
                System.out.println("退出表头前面插入操作！！！");
                break;
            }
            linkedList.insertFirst(val);
            linkedList.printLinkedList(linkedList.first);
            System.out.println();
        }
        while(true) {
            System.out.print("请输入一个整数作为新插入节点值插在表尾后面（输入 -1 退出）：");
            int val=Integer.parseInt(in.readLine());
            if(val==-1) {
                System.out.println("退出表尾后面插入操作！！！");
                break;
            }
            linkedList.insertLast(val);
            linkedList.printLinkedList(linkedList.first);
            System.out.println();
        }
        while(true) {
            System.out.print("请输入一个链表中存在的整数，新节点插在它后面：");
            int target=Integer.parseInt(in.readLine());
            System.out.print("请输入一个整数作为新插入节点值插在中间某节点后面（输入 -1 退出）：");
            int val=Integer.parseInt(in.readLine());
            if(val==-1) {
                System.out.println("退出插入某中间节点后面的操作！！！");
                break;
            }
            linkedList.insert(target,val);
            linkedList.printLinkedList(linkedList.first);
            System.out.println();
        }
        while(true) {
            System.out.print("请输入一个整数检查链表里是否存在（输入 -1 退出）：");
            int val=Integer.parseInt(in.readLine());
            if(val==-1) {
                System.out.println("退出查询操作！！！");
                break;
            }
            linkedList.search(val);
            System.out.println();
        }
        while(true) {
            System.out.print("输入 1 删除表头（输入 -1 退出）：");
            int val=Integer.parseInt(in.readLine());
            if(val==-1) {
                System.out.println("退出删除表头操作！！！");
                break;
            }
            if(val==1)
            linkedList.deleteFirst(linkedList.first);
            linkedList.printLinkedList(linkedList.first);
            System.out.println();
        }
        while(true) {
            System.out.print("输入 1 删除表尾（输入 -1 退出）：");
            int val=Integer.parseInt(in.readLine());
            if(val==-1) {
                System.out.println("退出删除表尾操作！！！");
                break;
            }
            if(val==1)
            linkedList.deleteLast(linkedList.first);
            linkedList.printLinkedList(linkedList.first);
            System.out.println();
        }
        while(true) {
            System.out.print("输入你想删除的节点整数值（输入 -1 退出）：");
            int val=Integer.parseInt(in.readLine());
            if(val==-1) {
                System.out.println("退出删除某值操作！！！");
                break;
            }
            if(val==1)
            linkedList.delete(val);
            linkedList.printLinkedList(linkedList.first);
            System.out.println();
        }
        // TODO Auto-generated method stub
    }

}