Java单链表的插入和删除操作

StudentNode

package com.zhangyu.linklisttest2.linkedlist;

import java.util.Objects;

/**
 * 节点类
 */
public class StudentNode {
    int id;//学号
    String name;//名字
    int data;//成绩
    StudentNode next;//下一个节点

    public StudentNode(int id, String name, int data) {
        this.id = id;
        this.name = name;
        this.data = data;
        next = null;
    }

    @Override
    public String toString() {
        return "StudentNode{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", data=" + data +
                ", next=" + next +
                '}';
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        StudentNode node = (StudentNode) o;
        return id == node.id &&
                data == node.data &&
                Objects.equals(name, node.name);
    }

    @Override
    public int hashCode() {
        return Objects.hash(id, name, data, next);
    }
}

StudentLinkedList

package com.zhangyu.linklisttest2.linkedlist;

import android.util.Log;

/**
 * 构建链表，头结点和尾节点指针
 */
public class StudentLinkedList {
    private static final String TAG = "StudentLinkedList";

    public StudentNode first;
    public StudentNode last;

    //判空
    public boolean isEmpty() {
        return first == null;
    }

    //打印表中内容
    public void print() {
        StudentNode current = first;
        while (current != null) {
            String s = current.toString();
            Log.e(TAG, "print: " + s);
            current = current.next;
        }
    }

    //插入数据
    public void insert(int id, String name, int data) {
        StudentNode node = new StudentNode(id, name, data);
        if (this.isEmpty()) {
            first = node;
            last = node;
        } else {
            last.next = node;
            last = node;
        }
    }

    //删除数据
    public void delete(StudentNode node) {
        if (isEmpty()) {
            Log.e(TAG, "delete: list is empty");
            return;
        }
        //1.删除头结点
        if (first.equals(node)) {
            Log.e(TAG, "delete: 删除头结点");
            first = first.next;
        }
        //2.删除尾节点
        else if (last.equals(node)) {
            Log.e(TAG, "delete: 删除尾节点");
            StudentNode tmpNode = first;
            while (tmpNode.next != last) {
                tmpNode = tmpNode.next;
            }
            tmpNode.next = last.next;//last.next = null
            last = tmpNode;
        }
        //3.删除中间节点
        else {
            StudentNode curNode = first.next;
            StudentNode preNode = first;
            while (curNode != null && !curNode.equals(node)) {
                curNode = curNode.next;
                preNode = preNode.next;
            }
            if (curNode != null && curNode.equals(node)) {
                preNode.next = curNode.next;
                Log.e(TAG, "delete: 删除中间节点");
            } else {
                Log.e(TAG, "delete: 该节点不存在");
            }
        }
        Log.e(TAG, "delete: 结束");
    }

}

Main

package com.zhangyu.linklisttest2;

import android.os.Bundle;
import android.util.Log;

import androidx.appcompat.app.AppCompatActivity;

import com.zhangyu.linklisttest2.linkedlist.StudentLinkedList;
import com.zhangyu.linklisttest2.linkedlist.StudentNode;

public class MainActivity extends AppCompatActivity {
    private static final String TAG = "MainActivity";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        StudentLinkedList linkedList = new StudentLinkedList();
        linkedList.insert(1,"张三",93);
        linkedList.insert(2,"李四",94);
        linkedList.insert(3,"王五",95);
        linkedList.insert(4,"赵六",96);
        linkedList.print();
        //
        Log.e(TAG, "delete" );
//        StudentNode node = new StudentNode(1, "张三", 93);
//        StudentNode node = new StudentNode(2, "李四", 94);
        StudentNode node = new StudentNode(4,"赵六",962);
        linkedList.delete(node);
        linkedList.print();
    }
}

节点不存在的情况

删除头结点

删除尾节点

删除中间节点