Hashmap(先沾上，有空具体分析)
public class HashMap<K,V> extends AbstractMap<K,V>
implements Map<K,V>, Cloneable, Serializable {
private static final long serialVersionUID = 362498820763181265L;
/**
* 默认容量为2的幂
*/
static final int DEFAULT_INITIAL_CAPACITY = 1 << 4;
// aka 16
/**
* 最大容量2的29次方
*/
static final int MAXIMUM_CAPACITY = 1 << 30;
/**
* 加载因子0.75，既保证不经常扩充容量，又保证容器的使用效率
*/
static final float DEFAULT_LOAD_FACTOR = 0.75f;
/**
* 当同一位置的元素数量大于8时转变为树形结构储存，而不是链表
*/
static final int TREEIFY_THRESHOLD = 8;
/**
* 当同一位置的元素数量小于6时，树形结构转变为链表储存
*/
static final int UNTREEIFY_THRESHOLD = 6;
/**
* 容器容量为64以上，时才进行树形化结构的变化，防止出现扩容和树形化的冲突
*/
static final int MIN_TREEIFY_CAPACITY = 64;
/**
* 节点继承了词条Map.Entry<K,V>，有哈希值、键、值、下一个节点四个属性
*/
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;
}
}
/**
* key的哈希值，有32位，一般来说只有后四位才有作用（取余），为了降低冲突的可能性
* 将哈希值右移16位，并用异或运算符得到最终的值
*/
static final int hash(Object key) {
int h;
return (key == null) ? 0 : (h = key.hashCode()) ^ (h >>> 16);
}
/**
* 表的容量
*/
static final int tableSizeFor(int cap) {
int n = cap - 1;
n |= n >>> 1;
n |= n >>> 2;
n |= n >>> 4;
n |= n >>> 8;
n |= n >>> 16;
return (n < 0) ? 1 : (n >= MAXIMUM_CAPACITY) ? MAXIMUM_CAPACITY : n + 1;
}
/**
*表的一些属性
*/
transient Node<K,V>[] table;
transient Set<Map.Entry<K,V>> entrySet;
transient int size;
transient int modCount;
int threshold;
final float loadFactor;
/* ---------------- 构造器 -------------- */
/**
* 带有容量和加载因子的构造器
*/
public HashMap(int initialCapacity, float loadFactor) {
if (initialCapacity < 0)
throw new IllegalArgumentException("Illegal initial capacity: " +
initialCapacity);
if (initialCapacity > MAXIMUM_CAPACITY)
initialCapacity = MAXIMUM_CAPACITY;
if (loadFactor <= 0 || float.isNaN(loadFactor))
throw new IllegalArgumentException("Illegal load factor: " +
loadFactor);
this.loadFactor = loadFactor;
this.threshold = tableSizeFor(initialCapacity);
}
/**
* 带有容量的构造器，加载因子默认0.75
*/
public HashMap(int initialCapacity) {
this(initialCapacity, DEFAULT_LOAD_FACTOR);
}
/**
* 构造器，加载因子默认0.75，容量16
*/
public HashMap() {
this.loadFactor = DEFAULT_LOAD_FACTOR;
}
/**
* 带有映射的构造器，加载因子0.75，将映射的数据加载到HashMap中
*/
public HashMap(Map<? extends K, ? extends V> m) {
this.loadFactor = DEFAULT_LOAD_FACTOR;
putMapEntries(m, false);
}
/**
* 相关方法
*/
final void putMapEntries(Map<? extends K, ? extends V> m, Boolean evict) {
int s = m.size();
if (s > 0) {
if (table == null) {
//容器位空
float ft = ((float)s / loadFactor) + 1.0F;
int t = ((ft < (float)MAXIMUM_CAPACITY) ?
(int)ft : MAXIMUM_CAPACITY);
if (t > threshold)
threshold = tableSizeFor(t);
} else if (s > threshold)//数据量大于扩容阈值，调用resize()扩容
resize();
for (Map.Entry<? extends K, ? extends V> e : m.entrySet()) {
//加载数据
K key = e.getKey();
V value = e.getValue();
putVal(hash(key), key, value, false, evict);
}
}
}
/**
* 通过哈希值和键得到值
*/
final Node<K,V> getNode(int hash, Object key) {
Node<K,V>[] tab;
Node<K,V> first, e;
int n;
K k;
if ((tab = table) != null && (n = tab.length) > 0 &&
(first = tab[(n - 1) & hash]) != null) {
if (first.hash == hash && // 检测该位置位于表中的数据是否复合
((k = first.key) == key || (key != null && key.equals(k))))
return first;
if ((e = first.next) != null) {
//检测位于链表或树中的数据
if (first instanceof TreeNode)//判断储存的结构类型
return ((TreeNode<K,V>)first).getTreeNode(hash, key);
do {
if (e.hash == hash &&
((k = e.key) == key || (key != null && key.equals(k))))
return e;
}
while ((e = e.next) != null);
}
}
return null;
}
/**
* 将哈希值和键已知的位置处，添加一个值
*/
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)//表为空时
n = (tab = resize()).length;
//初始化，容量为16，扩容阈值12
if ((p = tab[i = (n - 1) & hash]) == null)//该位置的数据为空
tab[i] = newNode(hash, key, value, null);
//储存数据 else {
//该位置处有值
Node<K,V> e;
K k;
if (p.hash == hash &&//key和哈希值相等的情况
((k = p.key) == key || (key != null && key.equals(k))))
e = p; else if (p instanceof TreeNode)//不相等，树形结构
e = ((TreeNode<K,V>)p).putTreeVal(this, tab, hash, key, value); else {
//链表结构
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
treeifyBin(tab, hash);
break;
}
if (e.hash == hash &&
((k = e.key) == key || (key != null && key.equals(k))))
break;
p = e;
}
}
if (e != null) {
// e不为空
V oldValue = e.value;
if (!onlyIfAbsent || oldValue == null)
e.value = value;
//覆盖值
afterNodeAccess(e);
return oldValue;
//返回e的值
}
}
++modCount;
if (++size > threshold)
resize();
afterNodeInsertion(evict);
//这个不同清楚
return null;
}
/**
* 对容量进行重新设定，扩容
*/
final Node<K,V>[] resize() {
Node<K,V>[] oldTab = table;
int oldCap = (oldTab == null) ? 0 : oldTab.length;
int oldThr = threshold;
int newCap, newThr = 0;
if (oldCap > 0) {
if (oldCap >= MAXIMUM_CAPACITY) {
threshold = Integer.MAX_VALUE;
return oldTab;
//已经最大，无法扩容，返回原表
} else if ((newCap = oldCap << 1) < MAXIMUM_CAPACITY &&//容量增加一倍并进行情况的分析
oldCap >= DEFAULT_INITIAL_CAPACITY)
newThr = oldThr << 1;
// 新的扩容阈值增加一倍
} else if (oldThr > 0) //原先容量为0，原先扩容阈值大于0
newCap = oldThr;
//将扩容阈值赋给新容量 else {
//设置默认容量16，扩容阈值12
newCap = DEFAULT_INITIAL_CAPACITY;
newThr = (int)(DEFAULT_LOAD_FACTOR * DEFAULT_INITIAL_CAPACITY);
}
if (newThr == 0) {
//上述情况二
float ft = (float)newCap * loadFactor;
//设置扩容阈值
newThr = (newCap < MAXIMUM_CAPACITY && ft < (float)MAXIMUM_CAPACITY ?
(int)ft : Integer.MAX_VALUE);
}
threshold = newThr;
@SuppressWarnings({
"rawtypes","unchecked"
}
)
Node<K,V>[] newTab = (Node<K,V>[])new Node[newCap];
table = newTab;
if (oldTab != null) {
for (int j = 0; j < oldCap; ++j) {
Node<K,V> e;
if ((e = oldTab[j]) != null) {
oldTab[j] = null;
//清空原先的表
if (e.next == null)//没有相邻节点
newTab[e.hash & (newCap - 1)] = e; else if (e instanceof TreeNode)//二叉树
((TreeNode<K,V>)e).split(this, newTab, j, oldCap); else {
// 链表
Node<K,V> loHead = null, loTail = null;
//还处于原来的位置
Node<K,V> hiHead = null, hiTail = null;
//不处于原来的位置
Node<K,V> next;
do {
next = e.next;
if ((e.hash & oldCap) == 0) {
//e的哈希值与老的容量的取余为0
if (loTail == null)//空的情况下
loHead = e;
//赋予e else
loTail.next = e;
//不空的情况，赋予该位置链表的尾端
loTail = e;
//最终链表尾端为e
} else {
if (hiTail == null)
hiHead = e; else
hiTail.next = e;
hiTail = e;
}
}
while ((e = next) != null);
if (loTail != null) {
loTail.next = null;
newTab[j] = loHead;
}
if (hiTail != null) {
hiTail.next = null;
newTab[j + oldCap] = hiHead;
}
}
}
}
}
return newTab;
}
/**
* 转变为二叉树结构
*/
final void treeifyBin(Node<K,V>[] tab, int hash) {
int n, index;
Node<K,V> e;
if (tab == null || (n = tab.length) < MIN_TREEIFY_CAPACITY)//如果表为空或表长小于最小容量
resize();
//重新改变容量 else if ((e = tab[index = (n - 1) & hash]) != null) {
//如果表的最后一个位置不为空
TreeNode<K,V> hd = null, tl = null;
//设置一头一尾
do {
TreeNode<K,V> p = replacementTreeNode(e, null);
//新建一个树节点
if (tl == null)//判断页节点是否为空
hd = p; else {
//不为空
p.prev = tl;
tl.next = p;
}
tl = p;
//设置为叶节点
}
while ((e = e.next) != null);
if ((tab[index] = hd) != null)
hd.treeify(tab);
//形成与此节点链接的节点树
}
}
public V remove(Object key) {
Node<K,V> e;
return (e = removeNode(hash(key), key, null, false, true)) == null ?
null : e.value;
}
/**
* 移除节点
*/
final Node<K,V> removeNode(int hash, Object key, Object value,
Boolean matchValue, Boolean movable) {
Node<K,V>[] tab;
Node<K,V> p;
int n, index;
if ((tab = table) != null && (n = tab.length) > 0 &&
(p = tab[index = (n - 1) & hash]) != null) {
//表中各位置都有数据
Node<K,V> node = null, e;
K k;
V v;
if (p.hash == hash &&//如果p的哈希值和键与要删除的完全相同
((k = p.key) == key || (key != null && key.equals(k))))
node = p; else if ((e = p.next) != null) {
if (p instanceof TreeNode)//二叉树结构
node = ((TreeNode<K,V>)p).getTreeNode(hash, key); else {
//链表结构
do {
if (e.hash == hash &&
((k = e.key) == key ||
(key != null && key.equals(k)))) {
node = e;
break;
}
p = e;
}
while ((e = e.next) != null);
//直到找到完全相等的值，或得知没有该对应的值
}
}
if (node != null && (!matchValue || (v = node.value) == value ||
(value != null && value.equals(v)))) {
//确认找到完全对应的值
if (node instanceof TreeNode)//树形结构
((TreeNode<K,V>)node).removeTreeNode(this, tab, movable); else if (node == p)//在表中位置上
tab[index] = node.next; else//在表的链表上
p.next = node.next;
++modCount;
--size;
afterNodeRemoval(node);
return node;
}
}
return null;
}
/**
* 键的集合与方法
*/
public Set<K> keySet() {
Set<K> ks = keySet;
if (ks == null) {
ks = new KeySet();
keySet = ks;
}
return ks;
}
final class KeySet extends AbstractSet<K> {
public final int size() {
return size;
}
public final void clear() {
HashMap.this.clear();
}
public final Iterator<K> iterator() {
return new KeyIterator();
}
public final Boolean contains(Object o) {
return containsKey(o);
}
public final Boolean remove(Object key) {
return removeNode(hash(key), key, null, false, true) != null;
}
public final Spliterator<K> spliterator() {
return new KeySpliterator<>(HashMap.this, 0, -1, 0, 0);
}
public final void forEach(Consumer<? super K> action) {
Node<K,V>[] tab;
if (action == null)
throw new NullPointerException();
if (size > 0 && (tab = table) != null) {
int mc = modCount;
for (int i = 0; i < tab.length; ++i) {
for (Node<K,V> e = tab[i]; e != null; e = e.next)
action.accept(e.key);
}
if (modCount != mc)
throw new ConcurrentModificationException();
}
}
}
/**
* 值的集合与方法
*/
public Collection<V> values() {
Collection<V> vs = values;
if (vs == null) {
vs = new Values();
values = vs;
}
return vs;
}
final class Values extends AbstractCollection<V> {
public final int size() {
return size;
}
public final void clear() {
HashMap.this.clear();
}
public final Iterator<V> iterator() {
return new ValueIterator();
}
public final Boolean contains(Object o) {
return containsValue(o);
}
public final Spliterator<V> spliterator() {
return new ValueSpliterator<>(HashMap.this, 0, -1, 0, 0);
}
public final void forEach(Consumer<? super V> action) {
Node<K,V>[] tab;
if (action == null)
throw new NullPointerException();
if (size > 0 && (tab = table) != null) {
int mc = modCount;
for (int i = 0; i < tab.length; ++i) {
for (Node<K,V> e = tab[i]; e != null; e = e.next)
action.accept(e.value);
}
if (modCount != mc)
throw new ConcurrentModificationException();
}
}
}
/**
* 词条的集合与方法
*/
public Set<Map.Entry<K,V>> entrySet() {
Set<Map.Entry<K,V>> es;
return (es = entrySet) == null ? (entrySet = new EntrySet()) : es;
}
final class EntrySet extends AbstractSet<Map.Entry<K,V>> {
public final int size() {
return size;
}
public final void clear() {
HashMap.this.clear();
}
public final Iterator<Map.Entry<K,V>> iterator() {
return new EntryIterator();
}
public final Boolean contains(Object o) {
if (!(o instanceof Map.Entry))
return false;
Map.Entry<?,?> e = (Map.Entry<?,?>) o;
Object key = e.getKey();
Node<K,V> candidate = getNode(hash(key), key);
return candidate != null && candidate.equals(e);
}
public final Boolean remove(Object o) {
if (o instanceof Map.Entry) {
Map.Entry<?,?> e = (Map.Entry<?,?>) o;
Object key = e.getKey();
Object value = e.getValue();
return removeNode(hash(key), key, value, true, true) != null;
}
return false;
}
public final Spliterator<Map.Entry<K,V>> spliterator() {
return new EntrySpliterator<>(HashMap.this, 0, -1, 0, 0);
}
public final void forEach(Consumer<? super Map.Entry<K,V>> action) {
Node<K,V>[] tab;
if (action == null)
throw new NullPointerException();
if (size > 0 && (tab = table) != null) {
int mc = modCount;
for (int i = 0; i < tab.length; ++i) {
for (Node<K,V> e = tab[i]; e != null; e = e.next)
action.accept(e);
}
if (modCount != mc)
throw new ConcurrentModificationException();
}
}
}
// jdk8增加的方法
@Override
public V getOrDefault(Object key, V defaultValue) {
Node<K,V> e;
return (e = getNode(hash(key), key)) == null ? defaultValue : e.value;
}
@Override
public V putIfAbsent(K key, V value) {
return putVal(hash(key), key, value, true, true);
}
@Override
public Boolean remove(Object key, Object value) {
return removeNode(hash(key), key, value, true, true) != null;
}
@Override
public Boolean replace(K key, V oldValue, V newValue) {
Node<K,V> e;
V v;
if ((e = getNode(hash(key), key)) != null &&
((v = e.value) == oldValue || (v != null && v.equals(oldValue)))) {
e.value = newValue;
afterNodeAccess(e);
return true;
}
return false;
}
@Override
public V replace(K key, V value) {
Node<K,V> e;
if ((e = getNode(hash(key), key)) != null) {
V oldValue = e.value;
e.value = value;
afterNodeAccess(e);
return oldValue;
}
return null;
}
@Override
public V computeIfAbsent(K key,
Function<? super K, ? extends V> mappingFunction) {
if (mappingFunction == null)
throw new NullPointerException();
int hash = hash(key);
Node<K,V>[] tab;
Node<K,V> first;
int n, i;
int binCount = 0;
TreeNode<K,V> t = null;
Node<K,V> old = null;
if (size > threshold || (tab = table) == null ||
(n = tab.length) == 0)//如果数量过多或过少，要对容器进行大小改变
n = (tab = resize()).length;
if ((first = tab[i = (n - 1) & hash]) != null) {
//找到对应的位置处，不为空
if (first instanceof TreeNode)//树形结构
old = (t = (TreeNode<K,V>)first).getTreeNode(hash, key); else {
//链表结构
Node<K,V> e = first;
K k;
do {
if (e.hash == hash &&
((k = e.key) == key || (key != null && key.equals(k)))) {
old = e;
break;
}
++binCount;
}
while ((e = e.next) != null);
}
V oldValue;
if (old != null && (oldValue = old.value) != null) {
//完全相同
afterNodeAccess(old);
return oldValue;
}
}
V v = mappingFunction.apply(key);
//得到V
if (v == null) {
//为空
return null;
} else if (old != null) {
//覆盖原值并返回
old.value = v;
afterNodeAccess(old);
return v;
} else if (t != null)//未找到对应值
t.putTreeVal(this, tab, hash, key, v);
//树形结构 else {
//链表
tab[i] = newNode(hash, key, v, first);
//判断是否进行变化
if (binCount >= TREEIFY_THRESHOLD - 1)
treeifyBin(tab, hash);
}
++modCount;
++size;
afterNodeInsertion(true);
return v;
//返回值
}
/**
* 遍历
*/
@Override
public void forEach(BiConsumer<? super K, ? super V> action) {
Node<K,V>[] tab;
if (action == null)
throw new NullPointerException();
if (size > 0 && (tab = table) != null) {
int mc = modCount;
for (int i = 0; i < tab.length; ++i) {
for (Node<K,V> e = tab[i]; e != null; e = e.next)
action.accept(e.key, e.value);
}
if (modCount != mc)//防止出现其他进程改变
throw new ConcurrentModificationException();
}
}
/**
* 克隆，键和值本身没有拷贝
*/
@SuppressWarnings("unchecked")
@Override
public Object clone() {
HashMap<K,V> result;
try {
result = (HashMap<K,V>)super.clone();
}
catch (CloneNotSupportedException e) {
// this shouldn't happen, since we are Cloneable
throw new InternalError(e);
}
result.reinitialize();
result.putMapEntries(this, false);
return result;
}
/* ---------------------迭代器--------------------------------------- */
abstract class HashIterator {
Node<K,V> next;
// next entry to return
Node<K,V> current;
// current entry
int expectedModCount;
// for fast-fail
int index;
// current slot
HashIterator() {
expectedModCount = modCount;
Node<K,V>[] t = table;
current = next = null;
index = 0;
if (t != null && size > 0) {
// advance to first entry
do {
}
while (index < t.length && (next = t[index++]) == null);
}
}
public final Boolean hasNext() {
return next != null;
}
final Node<K,V> nextNode() {
Node<K,V>[] t;
Node<K,V> e = next;
if (modCount != expectedModCount)
throw new ConcurrentModificationException();
if (e == null)
throw new NoSuchElementException();
if ((next = (current = e).next) == null && (t = table) != null) {
do {
}
while (index < t.length && (next = t[index++]) == null);
}
return e;
}
public final void remove() {
Node<K,V> p = current;
if (p == null)
throw new IllegalStateException();
if (modCount != expectedModCount)
throw new ConcurrentModificationException();
current = null;
K key = p.key;
removeNode(hash(key), key, null, false, false);
expectedModCount = modCount;
}
}
final class KeyIterator extends HashIterator
implements Iterator<K> {
public final K next() {
return nextNode().key;
}
}
final class ValueIterator extends HashIterator
implements Iterator<V> {
public final V next() {
return nextNode().value;
}
}
final class EntryIterator extends HashIterator
implements Iterator<Map.Entry<K,V>> {
public final Map.Entry<K,V> next() {
return nextNode();
}
}
/* ---------------------------分裂--------------------------------- */
//https://blog.csdn.net/sawiii/article/details/100068823
/**
*树形结构
*
*/
static final class TreeNode<K,V> extends LinkedHashMap.Entry<K,V> {
TreeNode<K,V> parent;
// red-black tree links
TreeNode<K,V> left;
TreeNode<K,V> right;
TreeNode<K,V> prev;
// needed to unlink next upon deletion
Boolean red;
TreeNode(int hash, K key, V val, Node<K,V> next) {
super(hash, key, val, next);
}
/**
* Returns root of tree containing this node.
*/
final TreeNode<K,V> root() {
for (TreeNode<K,V> r = this, p;;) {
if ((p = r.parent) == null)
return r;
r = p;
}
}
/**
* Ensures that the given root is the first node of its bin.
*/
static <K,V> void moveRootToFront(Node<K,V>[] tab, TreeNode<K,V> root) {
int n;
if (root != null && tab != null && (n = tab.length) > 0) {
int index = (n - 1) & root.hash;
TreeNode<K,V> first = (TreeNode<K,V>)tab[index];
if (root != first) {
Node<K,V> rn;
tab[index] = root;
TreeNode<K,V> rp = root.prev;
if ((rn = root.next) != null)
((TreeNode<K,V>)rn).prev = rp;
if (rp != null)
rp.next = rn;
if (first != null)
first.prev = root;
root.next = first;
root.prev = null;
}
assert checkInvariants(root);
}
}
/**
* Finds the node starting at root p with the given hash and key.
* The kc argument caches comparableClassFor(key) upon first use
* comparing keys.
*/
final TreeNode<K,V> find(int h, Object k, Class<?> kc) {
TreeNode<K,V> p = this;
do {
int ph, dir;
K pk;
TreeNode<K,V> pl = p.left, pr = p.right, q;
if ((ph = p.hash) > h)
p = pl; else if (ph < h)
p = pr; else if ((pk = p.key) == k || (k != null && k.equals(pk)))
return p; else if (pl == null)
p = pr; else if (pr == null)
p = pl; else if ((kc != null ||
(kc = comparableClassFor(k)) != null) &&
(dir = compareComparables(kc, k, pk)) != 0)
p = (dir < 0) ? pl : pr; else if ((q = pr.find(h, k, kc)) != null)
return q; else
p = pl;
}
while (p != null);
return null;
}
/**
* Calls find for root node.
*/
final TreeNode<K,V> getTreeNode(int h, Object k) {
return ((parent != null) ? root() : this).find(h, k, null);
}
/**
* Tie-breaking utility for ordering insertions when equal
* hashCodes and non-comparable. We don't require a total
* order, just a consistent insertion rule to maintain
* equivalence across rebalancings. Tie-breaking further than
* necessary simplifies testing a bit.
*/
static int tieBreakOrder(Object a, Object b) {
int d;
if (a == null || b == null ||
(d = a.getClass().getName().
compareTo(b.getClass().getName())) == 0)
d = (System.identityHashCode(a) <= System.identityHashCode(b) ?
-1 : 1);
return d;
}
/**
* Forms tree of the nodes linked from this node.
* @return root of tree
*/
final void treeify(Node<K,V>[] tab) {
TreeNode<K,V> root = null;
for (TreeNode<K,V> x = this, next; x != null; x = next) {
next = (TreeNode<K,V>)x.next;
x.left = x.right = null;
if (root == null) {
x.parent = null;
x.red = false;
root = x;
} else {
K k = x.key;
int h = x.hash;
Class<?> kc = null;
for (TreeNode<K,V> p = root;;) {
int dir, ph;
K pk = p.key;
if ((ph = p.hash) > h)
dir = -1; else if (ph < h)
dir = 1; else if ((kc == null &&
(kc = comparableClassFor(k)) == null) ||
(dir = compareComparables(kc, k, pk)) == 0)
dir = tieBreakOrder(k, pk);
TreeNode<K,V> xp = p;
if ((p = (dir <= 0) ? p.left : p.right) == null) {
x.parent = xp;
if (dir <= 0)
xp.left = x; else
xp.right = x;
root = balanceInsertion(root, x);
break;
}
}
}
}
moveRootToFront(tab, root);
}
/**
* Returns a list of non-TreeNodes replacing those linked from
* this node.
*/
final Node<K,V> untreeify(HashMap<K,V> map) {
Node<K,V> hd = null, tl = null;
for (Node<K,V> q = this; q != null; q = q.next) {
Node<K,V> p = map.replacementNode(q, null);
if (tl == null)
hd = p; else
tl.next = p;
tl = p;
}
return hd;
}
/**
* Tree version of putVal.
*/
final TreeNode<K,V> putTreeVal(HashMap<K,V> map, Node<K,V>[] tab,
int h, K k, V v) {
Class<?> kc = null;
Boolean searched = false;
TreeNode<K,V> root = (parent != null) ? root() : this;
for (TreeNode<K,V> p = root;;) {
int dir, ph;
K pk;
if ((ph = p.hash) > h)
dir = -1; else if (ph < h)
dir = 1; else if ((pk = p.key) == k || (k != null && k.equals(pk)))
return p; else if ((kc == null &&
(kc = comparableClassFor(k)) == null) ||
(dir = compareComparables(kc, k, pk)) == 0) {
if (!searched) {
TreeNode<K,V> q, ch;
searched = true;
if (((ch = p.left) != null &&
(q = ch.find(h, k, kc)) != null) ||
((ch = p.right) != null &&
(q = ch.find(h, k, kc)) != null))
return q;
}
dir = tieBreakOrder(k, pk);
}
TreeNode<K,V> xp = p;
if ((p = (dir <= 0) ? p.left : p.right) == null) {
Node<K,V> xpn = xp.next;
TreeNode<K,V> x = map.newTreeNode(h, k, v, xpn);
if (dir <= 0)
xp.left = x; else
xp.right = x;
xp.next = x;
x.parent = x.prev = xp;
if (xpn != null)
((TreeNode<K,V>)xpn).prev = x;
moveRootToFront(tab, balanceInsertion(root, x));
return null;
}
}
}
/**
* Removes the given node, that must be present before this call.
* This is messier than typical red-black deletion code because we
* cannot swap the contents of an interior node with a leaf
* successor that is pinned by "next" pointers that are accessible
* independently during traversal. So instead we swap the tree
* linkages. If the current tree appears to have too few nodes,
* the bin is converted back to a plain bin. (The test triggers
* somewhere between 2 and 6 nodes, depending on tree structure).
*/
final void removeTreeNode(HashMap<K,V> map, Node<K,V>[] tab,
Boolean movable) {
int n;
if (tab == null || (n = tab.length) == 0)
return;
int index = (n - 1) & hash;
TreeNode<K,V> first = (TreeNode<K,V>)tab[index], root = first, rl;
TreeNode<K,V> succ = (TreeNode<K,V>)next, pred = prev;
if (pred == null)
tab[index] = first = succ; else
pred.next = succ;
if (succ != null)
succ.prev = pred;
if (first == null)
return;
if (root.parent != null)
root = root.root();
if (root == null || root.right == null ||
(rl = root.left) == null || rl.left == null) {
tab[index] = first.untreeify(map);
// too small
return;
}
TreeNode<K,V> p = this, pl = left, pr = right, replacement;
if (pl != null && pr != null) {
TreeNode<K,V> s = pr, sl;
while ((sl = s.left) != null) // find successor
s = sl;
Boolean c = s.red;
s.red = p.red;
p.red = c;
// swap colors
TreeNode<K,V> sr = s.right;
TreeNode<K,V> pp = p.parent;
if (s == pr) {
// p was s's direct parent
p.parent = s;
s.right = p;
} else {
TreeNode<K,V> sp = s.parent;
if ((p.parent = sp) != null) {
if (s == sp.left)
sp.left = p; else
sp.right = p;
}
if ((s.right = pr) != null)
pr.parent = s;
}
p.left = null;
if ((p.right = sr) != null)
sr.parent = p;
if ((s.left = pl) != null)
pl.parent = s;
if ((s.parent = pp) == null)
root = s; else if (p == pp.left)
pp.left = s; else
pp.right = s;
if (sr != null)
replacement = sr; else
replacement = p;
} else if (pl != null)
replacement = pl; else if (pr != null)
replacement = pr; else
replacement = p;
if (replacement != p) {
TreeNode<K,V> pp = replacement.parent = p.parent;
if (pp == null)
root = replacement; else if (p == pp.left)
pp.left = replacement; else
pp.right = replacement;
p.left = p.right = p.parent = null;
}
TreeNode<K,V> r = p.red ? root : balanceDeletion(root, replacement);
if (replacement == p) {
// detach
TreeNode<K,V> pp = p.parent;
p.parent = null;
if (pp != null) {
if (p == pp.left)
pp.left = null; else if (p == pp.right)
pp.right = null;
}
}
if (movable)
moveRootToFront(tab, r);
}
final void split(HashMap<K,V> map, Node<K,V>[] tab, int index, int bit) {
TreeNode<K,V> b = this;
// Relink into lo and hi lists, preserving order
TreeNode<K,V> loHead = null, loTail = null;
TreeNode<K,V> hiHead = null, hiTail = null;
int lc = 0, hc = 0;
for (TreeNode<K,V> e = b, next; e != null; e = next) {
next = (TreeNode<K,V>)e.next;
e.next = null;
if ((e.hash & bit) == 0) {
if ((e.prev = loTail) == null)
loHead = e; else
loTail.next = e;
loTail = e;
++lc;
} else {
if ((e.prev = hiTail) == null)
hiHead = e; else
hiTail.next = e;
hiTail = e;
++hc;
}
}
if (loHead != null) {
if (lc <= UNTREEIFY_THRESHOLD)
tab[index] = loHead.untreeify(map); else {
tab[index] = loHead;
if (hiHead != null) // (else is already treeified)
loHead.treeify(tab);
}
}
if (hiHead != null) {
if (hc <= UNTREEIFY_THRESHOLD)
tab[index + bit] = hiHead.untreeify(map); else {
tab[index + bit] = hiHead;
if (loHead != null)
hiHead.treeify(tab);
}
}
}
/* ------------------------------------------------------------ */
// Red-black tree methods, all adapted from CLR
static <K,V> TreeNode<K,V> rotateLeft(TreeNode<K,V> root,
TreeNode<K,V> p) {
TreeNode<K,V> r, pp, rl;
if (p != null && (r = p.right) != null) {
if ((rl = p.right = r.left) != null)
rl.parent = p;
if ((pp = r.parent = p.parent) == null)
(root = r).red = false; else if (pp.left == p)
pp.left = r; else
pp.right = r;
r.left = p;
p.parent = r;
}
return root;
}
static <K,V> TreeNode<K,V> rotateRight(TreeNode<K,V> root,
TreeNode<K,V> p) {
TreeNode<K,V> l, pp, lr;
if (p != null && (l = p.left) != null) {
if ((lr = p.left = l.right) != null)
lr.parent = p;
if ((pp = l.parent = p.parent) == null)
(root = l).red = false; else if (pp.right == p)
pp.right = l; else
pp.left = l;
l.right = p;
p.parent = l;
}
return root;
}
static <K,V> TreeNode<K,V> balanceInsertion(TreeNode<K,V> root,
TreeNode<K,V> x) {
x.red = true;
for (TreeNode<K,V> xp, xpp, xppl, xppr;;) {
if ((xp = x.parent) == null) {
x.red = false;
return x;
} else if (!xp.red || (xpp = xp.parent) == null)
return root;
if (xp == (xppl = xpp.left)) {
if ((xppr = xpp.right) != null && xppr.red) {
xppr.red = false;
xp.red = false;
xpp.red = true;
x = xpp;
} else {
if (x == xp.right) {
root = rotateLeft(root, x = xp);
xpp = (xp = x.parent) == null ? null : xp.parent;
}
if (xp != null) {
xp.red = false;
if (xpp != null) {
xpp.red = true;
root = rotateRight(root, xpp);
}
}
}
} else {
if (xppl != null && xppl.red) {
xppl.red = false;
xp.red = false;
xpp.red = true;
x = xpp;
} else {
if (x == xp.left) {
root = rotateRight(root, x = xp);
xpp = (xp = x.parent) == null ? null : xp.parent;
}
if (xp != null) {
xp.red = false;
if (xpp != null) {
xpp.red = true;
root = rotateLeft(root, xpp);
}
}
}
}
}
}
static <K,V> TreeNode<K,V> balanceDeletion(TreeNode<K,V> root,
TreeNode<K,V> x) {
for (TreeNode<K,V> xp, xpl, xpr;;) {
if (x == null || x == root)
return root; else if ((xp = x.parent) == null) {
x.red = false;
return x;
} else if (x.red) {
x.red = false;
return root;
} else if ((xpl = xp.left) == x) {
if ((xpr = xp.right) != null && xpr.red) {
xpr.red = false;
xp.red = true;
root = rotateLeft(root, xp);
xpr = (xp = x.parent) == null ? null : xp.right;
}
if (xpr == null)
x = xp; else {
TreeNode<K,V> sl = xpr.left, sr = xpr.right;
if ((sr == null || !sr.red) &&
(sl == null || !sl.red)) {
xpr.red = true;
x = xp;
} else {
if (sr == null || !sr.red) {
if (sl != null)
sl.red = false;
xpr.red = true;
root = rotateRight(root, xpr);
xpr = (xp = x.parent) == null ?
null : xp.right;
}
if (xpr != null) {
xpr.red = (xp == null) ? false : xp.red;
if ((sr = xpr.right) != null)
sr.red = false;
}
if (xp != null) {
xp.red = false;
root = rotateLeft(root, xp);
}
x = root;
}
}
} else {
// symmetric
if (xpl != null && xpl.red) {
xpl.red = false;
xp.red = true;
root = rotateRight(root, xp);
xpl = (xp = x.parent) == null ? null : xp.left;
}
if (xpl == null)
x = xp; else {
TreeNode<K,V> sl = xpl.left, sr = xpl.right;
if ((sl == null || !sl.red) &&
(sr == null || !sr.red)) {
xpl.red = true;
x = xp;
} else {
if (sl == null || !sl.red) {
if (sr != null)
sr.red = false;
xpl.red = true;
root = rotateLeft(root, xpl);
xpl = (xp = x.parent) == null ?
null : xp.left;
}
if (xpl != null) {
xpl.red = (xp == null) ? false : xp.red;
if ((sl = xpl.left) != null)
sl.red = false;
}
if (xp != null) {
xp.red = false;
root = rotateRight(root, xp);
}
x = root;
}
}
}
}
}
/**
* Recursive invariant check
*/
static <K,V> Boolean checkInvariants(TreeNode<K,V> t) {
TreeNode<K,V> tp = t.parent, tl = t.left, tr = t.right,
tb = t.prev, tn = (TreeNode<K,V>)t.next;
if (tb != null && tb.next != t)
return false;
if (tn != null && tn.prev != t)
return false;
if (tp != null && t != tp.left && t != tp.right)
return false;
if (tl != null && (tl.parent != t || tl.hash > t.hash))
return false;
if (tr != null && (tr.parent != t || tr.hash < t.hash))
return false;
if (t.red && tl != null && tl.red && tr != null && tr.red)
return false;
if (tl != null && !checkInvariants(tl))
return false;
if (tr != null && !checkInvariants(tr))
return false;
return true;
}
}
}
Hashtable
package java.util;
import java.io.*;
import java.util.concurrent.ThreadLocalRandom;
import java.util.function.BiConsumer;
import java.util.function.Function;
import java.util.function.BiFunction;
/*
和HashMap一样，Hashtable 也是一个散列表，它存储的内容是键值对(key-value)映射。
Hashtable 继承于Dictionary，实现了Map、Cloneable、java.io.Serializable接口。
Hashtable 的函数都是同步的，这意味着它是线程安全的。它的key、value都不可以为null。
此外，Hashtable中的映射不是有序的。
*/
public class Hashtable<K,V>
extends Dictionary<K,V>
implements Map<K,V>, Cloneable, java.io.Serializable {
/**
* hashtable中的数据
*/
private transient Entry<?,?>[] table;
/**
* 表中的元素的实际数量
*/
private transient int count;
/**
* 阈值，判断是否需要调整容量
*/
private int threshold;
/**
* 加载因子，一般0.75
*/
private float loadFactor;
/**
*对于表的操作次数，可以判断
*是否有并发线程对其进行改动，并返回错误
*/
private transient int modCount = 0;
/**
*版本号
*/
private static final long serialVersionUID = 1421746759512286392L;
/**
* 构造器：有初始容量和加载因子
*/
public Hashtable(int initialCapacity, float loadFactor) {
if (initialCapacity < 0)
throw new IllegalArgumentException("Illegal Capacity: "+
initialCapacity);
if (loadFactor <= 0 || float.isNaN(loadFactor))
throw new IllegalArgumentException("Illegal Load: "+loadFactor);
if (initialCapacity==0)
initialCapacity = 1;
//以上是对极端情况的调整判断
this.loadFactor = loadFactor;
table = new Entry<?,?>[initialCapacity];
threshold = (int)Math.min(initialCapacity * loadFactor, MAX_ARRAY_SIZE + 1);
//阈值大小
}
/**
* 构造器：加载因子为0.75默认，有初始容量
*/
public Hashtable(int initialCapacity) {
this(initialCapacity, 0.75f);
}
/**
* 构造器：加载因子0.75，初始容量11
*/
public Hashtable() {
this(11, 0.75f);
}
/**
* 构造器：有Map映射，构造器初始容量大于映射的两倍
*/
public Hashtable(Map<? extends K, ? extends V> t) {
this(Math.max(2*t.size(), 11), 0.75f);
putAll(t);
}
/**
* 最大容量为int最大值-8
*/
private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
/**
* 动态改变容量大小
*/
@SuppressWarnings("unchecked")
protected void rehash() {
int oldCapacity = table.length;
//记录表的老容量
Entry<?,?>[] oldMap = table;
//记录表的数据
// overflow-conscious code
int newCapacity = (oldCapacity << 1) + 1;
//判断新的容量与最大值的关系
if (newCapacity - MAX_ARRAY_SIZE > 0) {
if (oldCapacity == MAX_ARRAY_SIZE)//判断老的容量与最大值的关系
return;
//相等就结束
newCapacity = MAX_ARRAY_SIZE;
}
Entry<?,?>[] newMap = new Entry<?,?>[newCapacity];
modCount++;
//操作次数增加
threshold = (int)Math.min(newCapacity * loadFactor, MAX_ARRAY_SIZE + 1);
//设置阈值
table = newMap;
for (int i = oldCapacity ; i-- > 0 ;) {
//每一个位置的每一条链
for (Entry<K,V> old = (Entry<K,V>)oldMap[i] ; old != null ; ) {
Entry<K,V> e = old;
old = old.next;
//一条链的下一个链接
int index = (e.hash & 0x7FFFFFFF) % newCapacity;
//从新计算引用位置
e.next = (Entry<K,V>)newMap[index];
//将这个与上一个链接
newMap[index] = e;
//赋值
}
}
}
/**
* 删除某个词条
*/
public synchronized V remove(Object key) {
Entry<?,?> tab[] = table;
int hash = key.hashCode();
int index = (hash & 0x7FFFFFFF) % tab.length;
@SuppressWarnings("unchecked")
Entry<K,V> e = (Entry<K,V>)tab[index];
//通过key计算hash值并进一步确定位置
for (Entry<K,V> prev = null ; e != null ; prev = e, e = e.next) {
if ((e.hash == hash) && e.key.equals(key)) {
modCount++;
if (prev != null) {
prev.next = e.next;
} else {
tab[index] = e.next;
//将key对应的词条的上和下链接起来
}
count--;
//数量减1
V oldValue = e.value;
e.value = null;
//对应处的数值改为Null
return oldValue;
}
}
return null;
}
/**
* 复制某一Map的所有词条至表中
*/
public synchronized void putAll(Map<? extends K, ? extends V> t) {
for (Map.Entry<? extends K, ? extends V> e : t.entrySet())
put(e.getKey(), e.getValue());
}
// Views
/**
* 所有的key,entry,values都要加一个锁，保证不发生并发改变的问题
*/
private transient volatile Set<K> keySet;
private transient volatile Set<Map.Entry<K,V>> entrySet;
private transient volatile Collection<V> values;
/**
*
*/
public Set<K> keySet() {
if (keySet == null)
keySet = Collections.synchronizedSet(new KeySet(), this);
return keySet;
}
private class KeySet extends AbstractSet<K> {
public Iterator<K> iterator() {
return getIterator(KEYS);
}
public int size() {
return count;
}
public Boolean contains(Object o) {
return containsKey(o);
}
public Boolean remove(Object o) {
return Hashtable.this.remove(o) != null;
}
public void clear() {
Hashtable.this.clear();
}
}
/**
*
*/
public Set<Map.Entry<K,V>> entrySet() {
if (entrySet==null)
entrySet = Collections.synchronizedSet(new EntrySet(), this);
return entrySet;
}
private class EntrySet extends AbstractSet<Map.Entry<K,V>> {
public Iterator<Map.Entry<K,V>> iterator() {
return getIterator(ENTRIES);
}
public Boolean add(Map.Entry<K,V> o) {
return super.add(o);
}
public Boolean contains(Object o) {
if (!(o instanceof Map.Entry))
return false;
Map.Entry<?,?> entry = (Map.Entry<?,?>)o;
Object key = entry.getKey();
Entry<?,?>[] tab = table;
int hash = key.hashCode();
int index = (hash & 0x7FFFFFFF) % tab.length;
for (Entry<?,?> e = tab[index]; e != null; e = e.next)
if (e.hash==hash && e.equals(entry))
return true;
return false;
}
public Boolean remove(Object o) {
if (!(o instanceof Map.Entry))
return false;
Map.Entry<?,?> entry = (Map.Entry<?,?>) o;
Object key = entry.getKey();
Entry<?,?>[] tab = table;
int hash = key.hashCode();
int index = (hash & 0x7FFFFFFF) % tab.length;
@SuppressWarnings("unchecked")
Entry<K,V> e = (Entry<K,V>)tab[index];
for (Entry<K,V> prev = null; e != null; prev = e, e = e.next) {
if (e.hash==hash && e.equals(entry)) {
modCount++;
if (prev != null)
prev.next = e.next; else
tab[index] = e.next;
count--;
e.value = null;
return true;
}
}
return false;
}
public int size() {
return count;
}
public void clear() {
Hashtable.this.clear();
}
}
/**
*
*/
public Collection<V> values() {
if (values==null)
values = Collections.synchronizedCollection(new ValueCollection(),
this);
return values;
}
private class ValueCollection extends AbstractCollection<V> {
public Iterator<V> iterator() {
return getIterator(VALUES);
}
public int size() {
return count;
}
public Boolean contains(Object o) {
return containsValue(o);
}
public void clear() {
Hashtable.this.clear();
}
}
/**
* 判等
*/
public synchronized Boolean equals(Object o) {
if (o == this)//正好相等
return true;
if (!(o instanceof Map))//类型不一致
return false;
Map<?,?> t = (Map<?,?>) o;
if (t.size() != size())
return false;
try {
//判断不相等
Iterator<Map.Entry<K,V>> i = entrySet().iterator();
while (i.hasNext()) {
Map.Entry<K,V> e = i.next();
K key = e.getKey();
V value = e.getValue();
if (value == null) {
if (!(t.get(key)==null && t.containsKey(key)))//不存在相同key值
return false;
} else {
if (!value.equals(t.get(key)))//key对应的位置存在但值不相等
return false;
}
}
}
catch (ClassCastException unused) {
return false;
}
catch (NullPointerException unused) {
return false;
}
return true;
}
/**
* 返回hashcode值
*/
public synchronized int hashCode() {
int h = 0;
if (count == 0 || loadFactor < 0)
return h;
// 空
loadFactor = -loadFactor;
// 加载因子改为负，作标记，不能被其他进程更改
Entry<?,?>[] tab = table;
for (Entry<?,?> entry : tab) {
while (entry != null) {
h += entry.hashCode();
//hashcode的计算方式：相加该位置所有链接的hash值
entry = entry.next;
}
}
loadFactor = -loadFactor;
return h;
}
/*
*按照key，value删除
*/
@Override
public synchronized Boolean remove(Object key, Object value) {
Objects.requireNonNull(value);
Entry<?,?> tab[] = table;
int hash = key.hashCode();
int index = (hash & 0x7FFFFFFF) % tab.length;
@SuppressWarnings("unchecked")
Entry<K,V> e = (Entry<K,V>)tab[index];
for (Entry<K,V> prev = null; e != null; prev = e, e = e.next) {
if ((e.hash == hash) && e.key.equals(key) && e.value.equals(value)) {
modCount++;
if (prev != null) {
prev.next = e.next;
} else {
tab[index] = e.next;
}
count--;
e.value = null;
return true;
}
}
return false;
}
/**
* 通过流保存文件
*/
private void writeObject(java.io.ObjectOutputStream s)
throws IOException {
Entry<Object, Object> entryStack = null;
synchronized (this) {
s.defaultWriteObject();
s.writeint(table.length);
s.writeint(count);
for (int index = 0; index < table.length; index++) {
Entry<?,?> entry = table[index];
while (entry != null) {
entryStack =
new Entry<>(0, entry.key, entry.value, entryStack);
entry = entry.next;
}
}
}
while (entryStack != null) {
s.writeObject(entryStack.key);
s.writeObject(entryStack.value);
entryStack = entryStack.next;
}
}
/**
* 词条
*/
private static class Entry<K,V> implements Map.Entry<K,V> {
final int hash;
final K key;
V value;
Entry<K,V> next;
protected Entry(int hash, K key, V value, Entry<K,V> next) {
this.hash = hash;
this.key = key;
this.value = value;
this.next = next;
}
@SuppressWarnings("unchecked")
protected Object clone() {
return new Entry<>(hash, key, value,
(next==null ? null : (Entry<K,V>) next.clone()));
}
// Map.Entry Ops
public K getKey() {
return key;
}
public V getValue() {
return value;
}
public V setValue(V value) {
if (value == null)
throw new NullPointerException();
V oldValue = this.value;
this.value = value;
return oldValue;
}
public Boolean equals(Object o) {
if (!(o instanceof Map.Entry))
return false;
Map.Entry<?,?> e = (Map.Entry<?,?>)o;
return (key==null ? e.getKey()==null : key.equals(e.getKey())) &&
(value==null ? e.getValue()==null : value.equals(e.getValue()));
}
public int hashCode() {
return hash ^ Objects.hashCode(value);
}
public String toString() {
return key.toString()+"="+value.toString();
}
}
}
