java系列-LinkedHashMap

1.插入新节点时，会将该节点加到链表尾部

public class LinkedHashMap<K,V> extends HashMap<K,V> implements Map<K,V>{/*** The head (eldest) of the doubly linked list.*/transient LinkedHashMapEntry<K,V> head;/*** The tail (youngest) of the doubly linked list.*/transient LinkedHashMapEntry<K,V> tail;Node<K,V> newNode(int hash, K key, V value, Node<K,V> e) {LinkedHashMapEntry<K,V> p = new LinkedHashMapEntry<K,V>(hash, key, value, e);linkNodeLast(p);return p;}// link at the end of listprivate void linkNodeLast(LinkedHashMapEntry<K,V> p) {LinkedHashMapEntry<K,V> last = tail;tail = p; //更新p为尾节点if (last == null){ //如果之前尾节点为null，说明链表为null，那更新头节点为phead = p;} else {p.before = last;last.after = p;}}
}

2. 移除一个元素后，会将该元素从链表移除

public class LinkedHashMap<K,V> extends HashMap<K,V> implements Map<K,V> {void afterNodeRemoval(Node<K,V> e) { // unlinkLinkedHashMapEntry<K,V> p = (LinkedHashMapEntry<K,V>)e, b = p.before, a = p.after;p.before = p.after = null;if (b == null){//之前p为headhead = a;//更新p的下一个元素为head} else{b.after = a;}if (a == null){//之前p为tailtail = b;} else{a.before = b;}}
}