Java中LinkedHashSet、LinkedHashMap源码详解

//1.无参构造方法
public LinkedHashSet() {
		/**调用父类HashSet的构造方法，dummy只是为了重载加的参数，没有具体含义
		HashSet(int initialCapacity, float loadFactor, boolean dummy) {
        	map = new LinkedHashMap<>(initialCapacity, loadFactor);
    	}
		**/
		//默认初始数组长度16，加载因子为0.75
        super(16, .75f, true);
    }
//2.有参构造方法，数组长度
public LinkedHashSet(int initialCapacity) {
        super(initialCapacity, .75f, true);
    }
//3.有参构造方法，数组长度及加载因子
public LinkedHashSet(int initialCapacity, float loadFactor) {
        super(initialCapacity, loadFactor, true);
    }

//此参数是元素排序，等于true的时候是按哈希值排序，等于false的时候是按插入顺序排序
final boolean accessOrder;
//1.无参构造方法
public LinkedHashMap() {
        super();
        accessOrder = false;
    }
//2.有参构造方法，数组长度
public LinkedHashMap(int initialCapacity) {
        super(initialCapacity);
        accessOrder = false;
    }
//3.有参构造方法，数组长度和加载因子
public LinkedHashMap(int initialCapacity, float loadFactor) {
        super(initialCapacity, loadFactor);
        accessOrder = false;
    }

Node<K,V> newNode(int hash, K key, V value, Node<K,V> next) {
        return new Node<>(hash, key, value, next);
    }
//HashMap的内部类Node
static class Node<K,V> implements Map.Entry<K,V> {
        final int hash;
        final K key;
        V value;
        Node<K,V> next;
        Node(int hash, K key, V value, Node<K,V> next) {
            this.hash = hash;
            this.key = key;
            this.value = value;
            this.next = next;
        }
        public final K getKey()        { return key; }
        public final V getValue()      { return value; }
        public final String toString() { return key + "=" + value; }
        public final int hashCode() {
            return Objects.hashCode(key) ^ Objects.hashCode(value);
        }
        public final V setValue(V newValue) {
            V oldValue = value;
            value = newValue;
            return oldValue;
        }
        public final boolean equals(Object o) {
            if (o == this)
                return true;
            if (o instanceof Map.Entry) {
                Map.Entry<?,?> e = (Map.Entry<?,?>)o;
                if (Objects.equals(key, e.getKey()) &&
                    Objects.equals(value, e.getValue()))
                    return true;
            }
            return false;
        }
    }

Node<K,V> newNode(int hash, K key, V value, Node<K,V> e) {
        LinkedHashMap.Entry<K,V> p =
            new LinkedHashMap.Entry<K,V>(hash, key, value, e);
        linkNodeLast(p);
        return p;
    }
//LinkedHashMap的内部类Entry<K,V> 
static class Entry<K,V> extends HashMap.Node<K,V> {
        Entry<K,V> before, after;
        Entry(int hash, K key, V value, Node<K,V> next) {
            super(hash, key, value, next);
        }
    }
//指针前后指向
private void linkNodeLast(LinkedHashMap.Entry<K,V> p) {
        LinkedHashMap.Entry<K,V> last = tail;
        tail = p;
        if (last == null)
            head = p;
        else {
            p.before = last;
            last.after = p;
        }
    }