基于链表的集合Set

链表集合

package set;

import java.util.LinkedList;

public class LinkedListSet<E> implements Set<E> {
    
    
    private LinkedList<E>list;

    public LinkedListSet(){
    
    
        list = new LinkedList<>();
    }
    @Override
    public void add(E e) {
    
    
        if (!list.contains(e)){
    
    
            list.addFirst(e);
        }
    }

    @Override
    public void remove(E e) {
    
    
        list.remove(e);
    }

    @Override
    public boolean contains(E e) {
    
    
        return list.contains(e);
    }

    @Override
    public int getSize() {
    
    
        return list.size();
    }

    @Override
    public boolean isEmpty() {
    
    
        return list.isEmpty();
    }
}

接口

package set;

public interface Set<E> {
    
    
    void add(E e);
    void remove(E e);
    boolean contains(E e);

    int getSize();

    boolean isEmpty();

}

链表

public class LinkedList<E> {
    
    
    //结点类
    private class Node {
    
    
        public E e;
        public Node next;

        public Node(E e, Node next) {
    
    
            this.e = e;
            this.next = next;
        }

        public Node(E e) {
    
    
            this(e, null);
        }

        public Node() {
    
    
            this(null, null);
        }

        @Override
        public String toString() {
    
    
            return e.toString();
        }
    }

    //虚拟头结点
    private Node dummyHead;
    private int size;

    public LinkedList() {
    
    
        dummyHead = new Node(null, null);
        size = 0;
    }

    //获取元素个数
    public int getSize() {
    
    
        return size;
    }

    //判断是否为空
    public boolean isEmpty() {
    
    
        return size == 0;
    }

    //在链表头添加新的元素
    public void addFirst(E e) {
    
    
//        Node node = new Node(e);
//        node.next=head;
//        head=node;
        add(0, e);
    }

    //在链表中间添加元素，找到待添加节点的前一个节点，修改指针
    public void add(int index, E e) {
    
    
        if (index < 0 || index > size) {
    
    
            throw new IllegalArgumentException("Add failed.Illegal index.");
        }

        Node prev = dummyHead;
        for (int i = 0; i < index; i++) {
    
    
            //向前移动，找到索引前一个节点
            prev = prev.next;
        }
//            Node node = new Node(e);
//            node.next=prev.next;
//            prev.next=node;
        prev.next = new Node(e, prev.next);
        size++;

    }

    public void addLast(E e) {
    
    
        add(size, e);
    }

    //获取链表的第index位置的元素
    public E get(int index) {
    
    
        if (index < 0 || index >= size) {
    
    
            throw new IllegalArgumentException("Add failed.Illegal index.");
        }
        Node cur = dummyHead.next;
        for (int i = 0; i < index; i++) {
    
    
            cur = cur.next;
        }
        return cur.e;
    }

    //获取链表的第一个元素
    public E getFirst() {
    
    
        return get(0);
    }

    //获取链表的最后一个元素
    public E getLast() {
    
    
        return get(size - 1);
    }

    //    修改链表的第index个位置的元素为e
    public void set(int index, E e) {
    
    
        if (index < 0 || index >= size) {
    
    
            throw new IllegalArgumentException("Set failed.Illegal index");
        }
        Node cur = dummyHead.next;
        for (int i = 0; i < index; i++) {
    
    
            cur = cur.next;
        }
        cur.e = e;

    }

    //查找链表中是否具有元素e,如果找到返回true否则向后查找，直到元素为空
    public boolean contains(E e) {
    
    
        Node cur = dummyHead.next;
        while (cur != null) {
    
    
            if (cur.e.equals(e)) {
    
    
                return true;
            } else {
    
    
                cur = cur.next;
            }
        }
        return false;
    }

    //删除指定元素index，返回删除元素  将要删除元素的前一个元素的指针指向下一个元素
    public E remove(int index) {
    
    
        if (index < 0 || index >= size) {
    
    
            throw new IllegalArgumentException("Remove failed.Index is illegal");
        }
        Node prev = dummyHead;
        for (int i = 0; i < index; i++) {
    
    
            prev = prev.next;
        }
        Node retNode = prev.next;
        prev.next = retNode.next;
        retNode.next = null;
        size--;
        return retNode.e;
    }

    //删除第一个元素
    public E removeFirst() {
    
    
        return remove(0);
    }

    //删除最后一个元素
    public E removeLast() {
    
    
        return remove(size - 1);
    }

    @Override
    public String toString() {
    
    
        StringBuilder stringBuilder = new StringBuilder();
//        Node cur = dummyHead.next;
//
//        while (cur != null) {
    
    
//            stringBuilder.append(cur + "->");
//            cur = cur.next;
//        }
//        stringBuilder.append("NULL");
        for (Node cur = dummyHead.next; cur != null; cur = cur.next) {
    
    
            stringBuilder.append(cur + "->");
        }
        stringBuilder.append("NULL");
        return stringBuilder.toString();
    }


    public static void main(String[] args) {
    
    
        LinkedList<Integer> linkedList = new LinkedList<>();
        for (int i = 0; i < 5; i++) {
    
    
            linkedList.addFirst(i);
            System.out.println(linkedList);
        }
        linkedList.add(2, 666);
        System.out.println(linkedList);

        linkedList.remove(2);
        System.out.println(linkedList);

        linkedList.removeFirst();
        System.out.println(linkedList);

        linkedList.removeLast();
        System.out.println(linkedList);

    }
}