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Java中一个单链表的增删查改

小磊z 2022-02-14 阅读 85

目录

定义火车类

定义车厢类

头插法

根据索引插入 

 尾插法

 测试

根据index查找

根据val查找 

 测试

根据index修改

测试 

根据索引删除

 删除头节点

删除尾节点

 测试

 判断索引是否合法

toString()方法

全部代码


定义火车类

/**
 * 火车类
 */
public class SingleLinkedList {
    //实际火车中的车厢个数
    private int size;
    //火车的头节点
    private Node head;
}

定义车厢类

/**
 * 车厢类
 */
class Node{
    //存储具体的数据
    int val;
    //保存下一节车厢的地址
    Node next;

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

  • 头插法

/**
     * 在火车头部插入元素
     * @param val
     */
    public void addFirst(int val){
        Node node = new Node(val);
        //判断火车头节点是否为空
        if(head == null){
            head = node;
        }
        else{
            node.next = head;
            head = node;
        }
        size++;
    }
  • 根据索引插入 

 /**
     * 根据索引插入
     * @param index
     * @param val
     */
    public void addIndex(int index,int val) {
        if (index < 0 || index > size) {
            System.out.println("索引输入错误!");
        } else {
            if (index == 0) {
                addFirst(val);
                return;
            }
            Node node = new Node(val);
            Node pre = head;
            for (int i = 0; i < index - 1; i++) {
                pre = pre.next;
            }
            node.next = pre.next;
            pre.next = node;
            size++;
        }

    }
  •  尾插法

/**
     * 尾插法
     * @param val
     */
    public void addLast(int val){
        addIndex(size,val);
    }
  •  测试

/**
 * @author happy
 */
public class Test {
    public static void main(String[] args) {
        SingleLinkedList singleLinkedList = new SingleLinkedList();
        singleLinkedList.addFirst(1);
        singleLinkedList.addFirst(3);
        singleLinkedList.addFirst(5);

        //5->3->1->NULL
        System.out.println(singleLinkedList);
        singleLinkedList.addIndex(0,2);
        singleLinkedList.addIndex(2,6);
        singleLinkedList.addIndex(4,8);

        //2->5->6->3->1->NULL
        System.out.println(singleLinkedList);
        singleLinkedList.addLast(7);

        //2->5->6->3->8->1->7->NULL
        System.out.println(singleLinkedList);
   }
}

  • 根据index查找

 /**
     * 根据用户输入的index查找对应值
     * @param index
     * @return
     */
    public int get(int index){
        if(indexCheck(index)){
            Node node = head;
            for (int i = 0; i <index ; i++) {
                node = node.next;
            }
            return node.val;
        }else {
            System.out.println("索引输入错误!");
            return -1;
        }
    }
  • 根据val查找 

/**
     * 判断当前链表中是否包含值为val的节点
     * @param val
     * @return
     */
    public boolean contains(int val){
        for (Node temp = head ; temp != null ; temp=temp.next) {
            if (temp.val == val){
                return true;
            }
        }
        return false;
    }
  •  测试

/**
 * @author happy
 */
public class Test {
    public static void main(String[] args) {
        SingleLinkedList singleLinkedList = new SingleLinkedList();
        singleLinkedList.addFirst(1);
        singleLinkedList.addFirst(3);
        singleLinkedList.addFirst(5);

        //5->3->1->NULL
        System.out.println(singleLinkedList);
        singleLinkedList.addIndex(0,2);
        singleLinkedList.addIndex(2,6);
        singleLinkedList.addIndex(4,8);

        //2->5->6->3->1->NULL
        System.out.println(singleLinkedList);
        singleLinkedList.addLast(7);

        //2->5->6->3->8->1->7->NULL
        System.out.println(singleLinkedList);



        //2
        System.out.println(singleLinkedList.get(0));

        //true
        System.out.println(singleLinkedList.contains(8));

    }
}

  • 根据index修改

/**
     * 将单链表中索引为index的节点值改为newVal
     * @param index
     * @param newVal
     * @return
     */
    public int set(int index,int newVal){
        Node node = head;
        if (indexCheck(index)){
            for (int i = 0; i < index; i++) {
                node = node.next;
            }
            int oldVal = node.val;
            node.val = newVal;
            return oldVal;
        }else {
            System.out.println("索引输入错误!");
            return -1;
        }

    }
  • 测试 

/**
 * @author happy
 */
public class Test {
    public static void main(String[] args) {
        SingleLinkedList singleLinkedList = new SingleLinkedList();
        singleLinkedList.addFirst(1);
        singleLinkedList.addFirst(3);
        singleLinkedList.addFirst(5);

        //5->3->1->NULL
        System.out.println(singleLinkedList);
        singleLinkedList.addIndex(0,2);
        singleLinkedList.addIndex(2,6);
        singleLinkedList.addIndex(4,8);

        //2->5->6->3->1->NULL
        System.out.println(singleLinkedList);
        singleLinkedList.addLast(7);

        //2->5->6->3->8->1->7->NULL
        System.out.println(singleLinkedList);



        //2
        System.out.println(singleLinkedList.get(0));

        //true
        System.out.println(singleLinkedList.contains(8));


        singleLinkedList.set(0,1);
        singleLinkedList.set(3,9);
        singleLinkedList.set(6,10);

        //1->5->6->9->8->1->10->NULL
        System.out.println(singleLinkedList);

    }
}

  • 根据索引删除

 /**
     * 根据索引删除
     * @param index
     */
    public void removeIndex(int index){
        if (indexCheck(index)){
            if(index == 0){
                Node node = head;
                head = head.next;
                node.next = null;
                size--;
            }else {
                Node pre = head;
                for (int i = 0; i < index-1; i++) {
                    pre = pre.next;
                }
                //cur是待删除节点
                Node cur = pre.next;
                pre.next = cur.next;
                cur.next = null;
                size--;
            }
        }else {
            System.out.println("索引输入错误!");
        }
    }
  •  删除头节点

public void removeFirst(){
        removeIndex(0);
    }
  • 删除尾节点

public void removeLast(){
        removeIndex(size-1);
    }
  •  测试

/**
 * @author happy
 */
public class Test {
    public static void main(String[] args) {
        SingleLinkedList singleLinkedList = new SingleLinkedList();
        singleLinkedList.addFirst(1);
        singleLinkedList.addFirst(3);
        singleLinkedList.addFirst(5);

        //5->3->1->NULL
        System.out.println(singleLinkedList);
        singleLinkedList.addIndex(0,2);
        singleLinkedList.addIndex(2,6);
        singleLinkedList.addIndex(4,8);

        //2->5->6->3->1->NULL
        System.out.println(singleLinkedList);
        singleLinkedList.addLast(7);

        //2->5->6->3->8->1->7->NULL
        System.out.println(singleLinkedList);



        //2
        System.out.println(singleLinkedList.get(0));

        //true
        System.out.println(singleLinkedList.contains(8));


        singleLinkedList.set(0,1);
        singleLinkedList.set(3,9);
        singleLinkedList.set(6,10);

        //1->5->6->9->8->1->10->NULL
        System.out.println(singleLinkedList);



        singleLinkedList.removeFirst();
        singleLinkedList.removeLast();

        //5->6->9->8->1->NULL
        System.out.println(singleLinkedList);
        singleLinkedList.removeIndex(0);
        singleLinkedList.removeIndex(2);
        singleLinkedList.removeIndex(2);

        //6->9->NULL
        System.out.println(singleLinkedList);
    }
}

 判断索引是否合法

public boolean indexCheck(int index){
        if (index<0 ||index>=size) {
            return false;
        }
        return true;
    }

toString()方法

public String toString(){
        String ret = "";
        Node node = head;
        while (node != null){
            ret += node.val;
            ret += "->";
            node = node.next;
        }
        ret += "NULL";
        return ret;

    }
}

全部代码

package daily_practice.day_11_27.seq;

/**
 * @author happy
 */

/**
 * 火车类
 */
public class SingleLinkedList {
    //实际火车中的车厢个数
    private int size;
    //火车的头节点
    private Node head;

    /**
     * 在火车头部插入元素
     * @param val
     */
    public void addFirst(int val){
        Node node = new Node(val);
        //判断火车头节点是否为空
        if(head == null){
            head = node;
        }
        else{
            node.next = head;
            head = node;
        }
        size++;
    }

    /**
     * 根据索引插入
     * @param index
     * @param val
     */
    public void addIndex(int index,int val) {
        if (index < 0 || index > size) {
            System.out.println("索引输入错误!");
        } else {
            if (index == 0) {
                addFirst(val);
                return;
            }
            Node node = new Node(val);
            Node pre = head;
            for (int i = 0; i < index - 1; i++) {
                pre = pre.next;
            }
            node.next = pre.next;
            pre.next = node;
            size++;
        }

    }

    /**
     * 尾插法
     * @param val
     */
    public void addLast(int val){
        addIndex(size,val);
        //出错,空指针异常
//        Node node = new Node(val);
//        if(head == null){
//            addFirst(val);
//        }
//        Node pre = head;
//        while (pre != null){
//            pre = pre.next;
//        }
//        pre.next = node;
//        size++;
    }

    /**
     * 根据用户输入的index查找对应值
     * @param index
     * @return
     */
    public int get(int index){
        if(indexCheck(index)){
            Node node = head;
            for (int i = 0; i <index ; i++) {
                node = node.next;
            }
            return node.val;
        }else {
            System.out.println("索引输入错误!");
            return -1;
        }
    }

    /**
     * 判断当前链表中是否包含值为val的节点
     * @param val
     * @return
     */
    public boolean contains(int val){
        for (Node temp = head ; temp != null ; temp=temp.next) {
            if (temp.val == val){
                return true;
            }
        }
        return false;
    }

    /**
     * 将单链表中索引为index的节点值改为newVal
     * @param index
     * @param newVal
     * @return
     */
    public int set(int index,int newVal){
        Node node = head;
        if (indexCheck(index)){
            for (int i = 0; i < index; i++) {
                node = node.next;
            }
            int oldVal = node.val;
            node.val = newVal;
            return oldVal;
        }else {
            System.out.println("索引输入错误!");
            return -1;
        }

    }

    public void removeFirst(){
        removeIndex(0);
    }

    /**
     * 根据索引删除
     * @param index
     */
    public void removeIndex(int index){
        if (indexCheck(index)){
            if(index == 0){
                Node node = head;
                head = head.next;
                node.next = null;
                size--;
            }else {
                Node pre = head;
                for (int i = 0; i < index-1; i++) {
                    pre = pre.next;
                }
                //cur是待删除节点
                Node cur = pre.next;
                pre.next = cur.next;
                cur.next = null;
                size--;
            }
        }else {
            System.out.println("索引输入错误!");
        }
    }

    public void removeLast(){
        removeIndex(size-1);
    }

    public boolean indexCheck(int index){
        if (index<0 ||index>=size) {
            return false;
        }
        return true;
    }

    public String toString(){
        String ret = "";
        Node node = head;
        while (node != null){
            ret += node.val;
            ret += "->";
            node = node.next;
        }
        ret += "NULL";
        return ret;

    }
}

/**
 * 车厢类
 */
class Node{
    //存储具体的数据
    int val;
    //保存下一节车厢的地址
    Node next;

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