java 單向鏈表實現

鏈表是一種常用的數據結構，理解了鏈表的結構和原理，我們也可以使用java來實現一個簡易的鏈表，麻雀雖小五臟俱全，o(^▽^)o

package com.basic.alogrithm;

public class BasicLink {
    public static void main(String[] args) {
        Link<Integer> tests = new Link<Integer>();
        tests.add(4);
        tests.add(3);
        tests.add(5);
        tests.add(4);
        tests.add(6);
        tests.add(4);
        // tests.add(null); // 異常
        System.out.println(tests.size);
        // System.out.println(tests.get(tests.size)); // 異常
        tests.remove(4);
        System.out.println(tests.size);
        System.out.println(tests.get(0));
        System.out.println(tests.get(1));
        System.out.println(tests.get(2));
    }
}

class Link<E> {
    static class Node<E> {
        private E value;
        private Node<E> next;

        public Node(E e) {
            this.value = e;
            this.next = null;
        }
    }
    int size = 0;
    Node<E> header = new Node<E>(null);

    void add(E e) {
        if (e == null) {
            throw new NullPointerException("e == null");
        }
        Node<E> node = new Node<E>(e);
        node.next = header.next;
        header.next = node;
        size++;
    }

    void remove(E e) {
        Node<E> prev = header;
        Node<E> node = header.next;
        while (node != null) {
            if (node.value.equals(e)) {
                Node<E> tmp = node;
                prev.next = node.next;
                node = prev.next;
                tmp.next = null; // for gc
                size--;
            } else {
                prev = node;
                node = node.next;
            }
        }
    }

    E get(int index) {
        if (index < 0 || index >= size) {
            throw new IndexOutOfBoundsException("index < 0 || index >= size");
        }
        int i = 0;
        Node<E> n = header.next;
        for (;n != null; ) {
            if (i == index) {
                return n.value;
            }
            n=n.next;
            i++;
        }
        return null;
    }

    int size() {
        return size;
    }
}