# List
# Map
# HashMap
initialCapacity 16, loadFactor 0.75
当数据量大于Capacity * loadFactor , 扩容2倍,
当容量大于64时, 当同一个hash链表数量 >=8,结构转为红黑树
当hash链表数量 <=6个,转为链表
final V putVal(int hash, K key, V value, boolean onlyIfAbsent,
boolean evict) {
Node<K,V>[] tab; Node<K,V> p; int n, i;
if ((tab = table) == null || (n = tab.length) == 0)
n = (tab = resize()).length;
if ((p = tab[i = (n - 1) & hash]) == null) // table位置无节点,创建新Node放入对应位置
tab[i] = newNode(hash, key, value, null);
else {
Node<K,V> e; K k;
if (p.hash == hash &&
((k = p.key) == key || (key != null && key.equals(k)))) // table对应位置有节点，如果hash值匹配，则替换
e = p;
else if (p instanceof TreeNode) // table对应位置有节点，如果table对应位置已经是一个TreeNode，不再是Node，也就说，table对应位置是TreeNode，表示已经从链表转换成了红黑树，则执行插入红黑树节点的逻辑
e = ((TreeNode<K,V>)p).putTreeVal(this, tab, hash, key, value);
else {
for (int binCount = 0; ; ++binCount) {
if ((e = p.next) == null) {
p.next = newNode(hash, key, value, null);
if (binCount >= TREEIFY_THRESHOLD - 1) // -1 for 1st >=7 变红黑树
treeifyBin(tab, hash);
break;
}
if (e.hash == hash &&
((k = e.key) == key || (key != null && key.equals(k)))) //K相同,替换
break;
p = e;
}
}
if (e != null) { // existing mapping for key
V oldValue = e.value;
if (!onlyIfAbsent || oldValue == null)
e.value = value;
afterNodeAccess(e);
return oldValue;
}
}
++modCount;
if (++size > threshold)
resize();
afterNodeInsertion(evict);
return null;
}
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# ConcurrentHashMap
put时对node加synchronized(f)锁