1.HashMap是一个数组＋链表/红黑树的结构，数组的下标在HashMap中称为Bucket值，每个数组项对应的是一个List
2.每个List中存放的是一个Entry对象，这个Entry对象是包含键和值的
HashMap类实现了诸多接口Map, Cloneable, Serializable
public class HashMap extends AbstractMap implements Map, Cloneable, Serializable {
常量
private static final long serialVersionUID =362498820763181265L;
//最小容量
static final int DEFAULT_INITIAL_CAPACITY =1 <<4; // aka 16
//最大容量
static final int MAXIMUM_CAPACITY =1 <<30;
//重载因子
static final float DEFAULT_LOAD_FACTOR =0.75f;
//链表的最大长度，超过之后变为红黑树
static final int TREEIFY_THRESHOLD =8;
//红黑树当总的元素量小于6时，变成链表
static final int UNTREEIFY_THRESHOLD =6;
//当桶中的bin元素被树化时，桶的最小容量必须大于4 * TREEIFY_THRESHOLD（树化的长度），否则进行resize扩容，
static final int MIN_TREEIFY_CAPACITY =64;
内部静态类Node
Basic hash bin node, used for most entries.
static class Node 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) {
//哈希值
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;
}
}
静态工具
/* ---------------- Static utilities -------------- */
//哈希化
static final int hash(Object key) {
int h;
//^优先级高于三目运算符，>>>无符号右移16位
//如果该类有hashCode的实现会优先调用自身的hashCode方法，没有的话将调用Object的hashCode方法；
return (key ==null) ? 0 : (h = key.hashCode()) ^ (h >>>16);
}
比较方法
static Class<?> comparableClassFor(Object x) {
if (x instanceof Comparable) {
Class c; Type[] ts, as; Type t; ParameterizedType p;
if ((c = x.getClass()) == String.class) // bypass checks
return c;
if ((ts = c.getGenericInterfaces()) !=null) {
for (int i = 0; i < ts.length; ++i) {
if (((t = ts[i])instanceof ParameterizedType) &&
((p = (ParameterizedType)t).getRawType() == Comparable.class) && (as = p.getActualTypeArguments()) !=null
&& as.length ==1
&& as[0] == c) // type arg is c
return c;
}
}
}
return null;
}
可比较的
@SuppressWarnings({"rawtypes","unchecked"}) // for cast to Comparable
//原文是/rawtypes , unchecked/
static int compareComparables(Class kc, Object k, Object x) {
//逻辑运算符高于三目运算符
return (x ==null || x.getClass() != kc ?0 :
((Comparable)k).compareTo(x));
}
为给定目标容量，返回一个容器的尺寸
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;
}
/* ---------------- Fields -------------- */
属性
transient Node[] table; //元素集合
transient Set<Map.Entry<K,V>> entrySet; //缓存的Map.Entry集合
transient int size; //大小
transient int modCount; // HashMap被改变的次数
//HashMap的阈值，用于判断是否需要调整HashMap的容量（threshold = 容量*加载因子）
int threshold;
final float loadFactor; // 加载因子实际大小
/* ---------------- Public operations -------------- */
构造器
//带初始化大小和负载因子的构造器
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);//大小为2的次幂
}
//不带负载因子的构造器，默认为0.75
public HashMap(int initialCapacity) {
this(initialCapacity, DEFAULT_LOAD_FACTOR);
}
//构造一个空的HashMap对象，默认打下为16，负载因子0.75
public HashMap() {
this.loadFactor =DEFAULT_LOAD_FACTOR; // all other fields defaulted
}
//通过Map构造一个HashMap， 负载因子默认为0.75，通过 putMapEntries方法，将Map中的值放入HashMap当中
public HashMap(Map<? extends K, ? extends V> m) {
this.loadFactor =DEFAULT_LOAD_FACTOR;
putMapEntries(m, false);
}
//Implements Map.putAll and Map constructor
final void putMapEntries(Map<? extends K, ? extends V> m, boolean evict) {
int s = m.size();
if (s >0) {//判断map的大小
if (table ==null) {// pre-size，判断hashMap的初始大小
float ft = ((float)s /loadFactor) +1.0F; //判断这个创建数组的大小
int t = ((ft < (float)MAXIMUM_CAPACITY) ? (int)ft : MAXIMUM_CAPACITY);
if (t >threshold)//设置容器大小 ， threshold初始为0
threshold = tableSizeFor(t);
} else if (s > threshold) //若大于现有长度将扩容
resize();//扩容
for (Map.Entry e : m.entrySet()) {
K key = e.getKey();
V value = e.getValue();
putVal(hash(key), key, value, false, evict);
}
}
}
获取当前的存储key-value的数量
public int size() {
return size;
}
判断是否为空
public boolean isEmpty() {
return size ==0;
}
按照key获取value
public V get(Object key) {
Node<K,V> e;
return (e = getNode(hash(key), key)) ==null ?null : e.value;
}
通过key和hashCode获取Node
final Node<K,V> getNode(int hash, Object key) {
Node<K,V>[] tab; Node<K,V> first, e; int n; K k;
//hash是key哈希化的int值，与数组的最大下标进行安位与运算，得出实际的位置
if ((tab =table) !=null && (n = tab.length) >0 && (first = tab[(n -1) & hash]) !=null) {
if (first.hash == hash &&// always check first node
((k = first.key) == key || (key !=null && key.equals(k))))
return first;
//若第一个并不是所要找的元素，则进行分类查找（树/链表）
if ((e = first.next) !=null) {
//树（红黑树）
if (first instanceof TreeNode)
return ((TreeNode<K,V>)first).getTreeNode(hash, key);
//链表
do {
if (e.hash == hash &&
((k = e.key) == key || (key !=null && key.equals(k))))
return e;
}while ((e = e.next) !=null);
}
}
return null;
}
判断是否包含某个key
public boolean containsKey(Object key) {
return getNode(hash(key), key) !=null;
}
放入Map
public V put(K key, V value) {
//参数：hashCode，key， value， onlyIfAbsent（如果原来的key不存在创建，存在则不做任何操作， false默认（即替代原有value），true）， evict（）
return putVal(hash(key), key, value, false, true);
}
插入HashMap
参数：hashCode，key， value， onlyIfAbsent（如果原来的key不存在创建，存在则不做任何操作， false默认（即替代原有value），true）， evict（用于LinkedHashMap中的尾部操作，这里没有实际意义。）
final V putVal(int hash, K key, V value, boolean onlyIfAbsent, boolean evict) {
Node<K,V>[] tab; Node<K,V> p; int n, i;
//判断长度是否为0，若为0，则初始化
if ((tab =table) ==null || (n = tab.length) ==0)
n = (tab = resize()).length;
//获取Node[] 数组的该位置是否有值，无值直接放入
if ((p = tab[i = (n -1) & hash]) ==null)
tab[i] = newNode(hash, key, value, null);
//有值的话，则添加到链表或者树上
else {
Node<K,V> e; K k;
//传入的hashCode和key都与现有的节点相同
if (p.hash == hash &&((k = p.key) == key || (key !=null && key.equals(k))))
e = p;
//传入的hashCode和key都与现有的节点不相同，则分为两种情况，树/链表
//树
else if (p instanceof TreeNode)
//插入一个树节点
e = ((TreeNode<K,V>)p).putTreeVal(this, tab, hash, key, value);
//链表
else {
for (int binCount =0; ; ++binCount) {
//下一个节点为空则创建
if ((e = p.next) ==null) {
//插入一个链表节点
p.next = newNode(hash, key, value, null);
//判断添加后链表的长度，超过8则转换为红黑树
if (binCount >=TREEIFY_THRESHOLD -1)// -1 for 1st
//转换为红黑树
treeifyBin(tab, hash);
break;
}
//哈希化找到该节点，则返回e
if (e.hash == hash &&
((k = e.key) == key || (key !=null && key.equals(k))))
break;
//将当前节点在付给p，继续循环
p = e;
}
}
if (e !=null) {// existing mapping for key
V oldValue = e.value;
//判断onlyIfAbsent，改写方式
if (!onlyIfAbsent || oldValue ==null)
e.value = value;
afterNodeAccess(e);//插入节点后，允许的回调方法，可重写
return oldValue;
}
}
++modCount;//结构被更改的次数
//当插入节点后，根据负载因子判断是否扩容
if (++size >threshold)
resize();
afterNodeInsertion(evict);//结构调整后，允许的回调函数
return null;
}
重新定义hashMap的大小，初始化或者2次幂的方式扩容
final Node<K,V>[] resize() {
Node<K,V>[] oldTab =table;
int oldCap = (oldTab ==null) ?0 : oldTab.length;
int oldThr = threshold;
int newCap, newThr =0;
//原本不为空，即为扩容
if (oldCap >0) {
//达到最大值
if (oldCap >=MAXIMUM_CAPACITY) {
threshold = Integer.MAX_VALUE;
return oldTab;
}
//按照2次幂方式扩容
else if ((newCap = oldCap <<1) < MAXIMUM_CAPACITY
&& oldCap >=DEFAULT_INITIAL_CAPACITY)
newThr = oldThr <<1; // double threshold
}
//如果有容量限制则为原值
else if (oldThr >0)// initial capacity was placed in threshold
newCap = oldThr;
//没有固定参数，设置为默认值
else {// zero initial threshold signifies using defaults
newCap =DEFAULT_INITIAL_CAPACITY;//16
newThr = (int)(DEFAULT_LOAD_FACTOR * DEFAULT_INITIAL_CAPACITY);
}
//确定新的存储量是多少
if (newThr ==0) {
float ft = (float)newCap *loadFactor;
newThr = (newCap < MAXIMUM_CAPACITY && ft < (float)MAXIMUM_CAPACITY? (int)ft : Integer.MAX_VALUE);
}
//新的阀值
threshold = newThr;
@SuppressWarnings({"rawtypes","unchecked"})
//创建一个新的数组
Node<K,V>[] newTab = (Node<K,V>[])new Node[newCap];
table = newTab;
if (oldTab !=null) {
for (int j =0; j < oldCap; ++j) {
Node e;
if ((e = oldTab[j]) !=null) {
oldTab[j] =null;
//如果没有链表和树直接付值
if (e.next ==null)
newTab[e.hash & (newCap -1)] = e;
//如果是红黑树
else if (e instanceof TreeNode)
//将树拆分成高低两个树，重新进行哈希化，然后put
((TreeNode<K,V>)e).split(this, newTab, j, oldCap);
//如果是链表的话
else {// preserve order
Node<K,V> loHead =null, loTail =null;
Node<K,V> hiHead =null, hiTail =null;
Node<K,V> next;
do {
next = e.next;
if ((e.hash & oldCap) ==0) {
if (loTail ==null) loHead = e;
else loTail.next = e;
loTail = e;
}
else {
if (hiTail ==null) hiHead = e;
else hiTail.next = e;
hiTail = e;
}
}while ((e = next) !=null);
//低位的放在原位
if (loTail !=null) {
loTail.next =null;
newTab[j] = loHead;
}
//将拆出来的链表或者树的节点放到新的扩容出来的区域
if (hiTail !=null) {
hiTail.next =null;
newTab[j + oldCap] = hiHead;
}
}
}
}
}
return newTab;
}
链表长度超过8，将调整链表为树
final void treeifyBin(Node<K,V>[] tab, int hash) {
int n, index; Node e;
//当有树存在时，最小容量必须大于4*树化阀值（8）。默认64
if (tab ==null || (n = tab.length) < MIN_TREEIFY_CAPACITY) resize();
else if ((e = tab[index = (n -1) & hash]) !=null) {
TreeNode<K,V> hd =null, tl =null;
//循环替换
do {
//将node节点化成TreeNode节点
TreeNode<K,V> p = replacementTreeNode(e, null);
//设置根节点
if (tl ==null)
hd = p;
//设置父节点
else {
p.prev = tl;
tl.next = p;
}
tl = p;
}while ((e = e.next) !=null);
//将头节点放到整个数组当中
if ((tab[index] = hd) !=null)
//从头节点开始树化
hd.treeify(tab);
}
}
将Map插入全部
public void putAll(Map m) {
putMapEntries(m, true);
}
删除节点
public V remove(Object key) {
Node e;
return (e = removeNode(hash(key), key, null, false, true)) ==null
? null : e.value;
}
删除节点
参数int hash（哈希值）, Object key, Object value（一般为nu l l）, boolean matchValue（是否value也一致时在删除，默认为false）, boolean movable（是否移动其他节点，在树的时候， 默认为true）
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;
//查找到要删除的桶
if ((tab =table) !=null && (n = tab.length) >0 &&
(p = tab[index = (n -1) & hash]) !=null) {
Node<K，V> node =null, e; K k; V v;
//查找节点
//没有树或链表
if (p.hash == hash &&((k = p.key) == key || (key !=null && key.equals(k))))
node = p;
//有树或链表
else if ((e = p.next) !=null) {
//树
if (p instanceof TreeNode)
node = ((TreeNode)p).getTreeNode(hash, key);
//链表
else {
do {
if (e.hash == hash && ((k = e.key) == key ||
(key !=null && key.equals(k)))) {
node = e;
break;
}
p = e;
}while ((e = e.next) !=null);
}
}
//获取到相应的node节点
if (node !=null && (!matchValue || (v = node.value) == value ||
(value !=null && value.equals(v)))) {
//树
if (node instanceof TreeNode)
((TreeNode)node).removeTreeNode(this, tab, movable);
//链表
//头节点
else if (node == p)
tab[index] = node.next;
//非头节点
else
p.next = node.next;
++modCount;
--size;
afterNodeRemoval(node);
return node;
}
}
return null;
}
清除方法
public void clear() {
Node<K,V>[] tab;
modCount++;
if ((tab =table) !=null &&size >0) {
size =0;
for (int i =0; i < tab.length; ++i)
tab[i] =null;
}
}
是否包含值
public boolean containsValue(Object value) {
Node[] tab; V v;
if ((tab =table) !=null &&size >0) {
for (int i =0; i < tab.length; ++i) {
for (Node e = tab[i]; e !=null; e = e.next) {
if ((v = e.value) == value ||(value !=null && value.equals(v)))
return true;
}
}
}
return false;
}
key的集合
public SetkeySet() {
Set ks =keySet;
if (ks ==null) {
ks =new KeySet();
keySet = ks;
}
return ks;
}
内部类KeySet
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;
}
//Spliterator就是为了并行遍历元素而设计的一个迭代器，对于迭代器中数据进行分割
public final Spliterator<K> spliterator() {
return new KeySpliterator<>(HashMap.this, 0, -1, 0, 0);
}
//遍历
public final void forEach(Consumer action) {
Node[] 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 e = tab[i]; e !=null; e = e.next)
action.accept(e.key);
}
if (modCount != mc)
throw new ConcurrentModificationException();
}
}
}
获取全部的值
public Collection<V> values() {
Collection vs =values;
if (vs ==null) {
vs =new Values();
values = vs;
}
return vs;
}
Value的集合类
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 e = tab[i]; e !=null; e = e.next)
action.accept(e.value);
}
if (modCount != mc)
throw new ConcurrentModificationException();
}
}
}
set集合
public Set<Map.Entry<K,V>> entrySet() {
Set<Map.Entry<K,V>> es;
return (es =entrySet) ==null ? (entrySet =new EntrySet()) : es;
}
内部类EntrySet
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 (!(oinstanceof 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> 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 e = tab[i]; e !=null; e = e.next)
action.accept(e);
}
if (modCount != mc)
throw new ConcurrentModificationException();
}
}
}
获取默认值
public V getOrDefault(Object key, V defaultValue) {
Node e;
return (e = getNode(hash(key), key)) ==null ? defaultValue : e.value;
}
key存在则不插入
public V putIfAbsent(K key, V value) {
return putVal(hash(key), key, value, true, true);
}
删除节点
public boolean remove(Object key, Object value) {
return removeNode(hash(key), key, value, true, true) !=null;
}
替换旧值
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;
fterNodeAccess(e);
return true;
}
return false;
}
替换旧值
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;
}
compute()是java8在Map中新增的一个方法，其作用是把remappingFunction的计算结果关联到key上（即remappingFunction返回值作为新value）
V computeIfAbsent根据key做匹配Node，（匹配不到则新建然后重排）如果Node有value，则直接返回oldValue，如果没有value则根据Function接口的apply方法获取value，返回value。Function接口的apply的入参为key，调用computeIfAbsent时重写Function接口可以根据key进行逻辑处理，apply的返回值即为要存储的value。
public V computeIfAbsent(K key,
Function mappingFunction<? 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)
n = (tab = resize()).length;
if ((first = tab[i = (n -1) & hash]) !=null) {
if (firstinstanceof TreeNode)
old = (t = (TreeNode)first).getTreeNode(hash, key);
else {
Node 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) {
afterNodeAccess(old);
return oldValue;
}
}
V v = mappingFunction.apply(key);
if (v ==null) {
return null;
}else if (old !=null) {
old.value = v;
afterNodeAccess(old);
return v;
}
else if (t !=null)
t.putTreeVal(this, tab, hash, key, v);
else {
tab[i] = newNode(hash, key, v, first);
if (binCount >=TREEIFY_THRESHOLD -1)
treeifyBin(tab, hash);
}
++modCount;
++size;
afterNodeInsertion(true);
return v;
}
V computeIfPresent(K key,BiFunction remappingFunction)：根据key做匹配，如果匹配不上则返回null,匹配上根据BiFunction的apply方法获取value，返回value。BiFunction接口的apply的入参为key、oldValue，调用computeIfPresent时重写Function接口可以根据key和oldValue进行逻辑处理，apply的返回值如果为null则删除该节点，否则即为要存储的value。
public V computeIfPresent(K key,
BiFunction<? super K, ? super V, ? super V> remappingFunction) {
if (remappingFunction ==null)
throw new NullPointerException();
Node<K,V> e; V oldValue;
int hash =hash(key);
if ((e = getNode(hash, key)) !=null &&(oldValue = e.value) !=null) {
V v = remappingFunction.apply(key, oldValue);
if (v !=null) {
e.value = v;
afterNodeAccess(e);
return v;
}
else
removeNode(hash, key, null, false, true);
}
return null;
}
V compute(K key,BiFunction remappingFunction)：根据key做匹配，根据BiFunction的apply返回做存储的value。匹配到Node做value替换，匹配不到新增node。apply的返回值如果为null则删除该节点，否则即为要存储的value。
public V compute(K key,
BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
if (remappingFunction ==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)
n = (tab = resize()).length;
if ((first = tab[i = (n -1) & hash]) !=null) {
if (first instanceof TreeNode)
old = (t = (TreeNode)first).getTreeNode(hash, key);
else {
Node 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 = (old ==null) ?null : old.value;
V v = remappingFunction.apply(key, oldValue);
if (old !=null) {
if (v !=null) {
old.value = v;
afterNodeAccess(old);
}
else removeNode(hash, key, null, false, true);
}
else if (v !=null) {
if (t !=null)
t.putTreeVal(this, tab, hash, key, v);
else {
tab[i] = newNode(hash, key, v, first);
if (binCount >=TREEIFY_THRESHOLD -1)
treeifyBin(tab, hash);
}
++modCount;
++size;
afterNodeInsertion(true);
}
return v;
}
V merge(K key, V value,BiFunction remappingFunction)：功能大部分与compute相同，不同之处在于BiFunction中apply的参数，入参为oldValue、value，调用merge时根据两个value进行逻辑处理并返回value。
public V merge(K key, V value,
BiFunction remappingFunction) {
if (value ==null)
throw new NullPointerException();
if (remappingFunction ==null)
throw new NullPointerException();
int hash =hash(key);
Node<K,V>[] tab; Node 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)
n = (tab = resize()).length;
if ((first = tab[i = (n -1) & hash]) !=null) {
if (first instanceof TreeNode)
old = (t = (TreeNode)first).getTreeNode(hash, key);
else {
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);
}
}
if (old !=null) {
V v;
if (old.value !=null)
v = remappingFunction.apply(old.value, value);
else
v = value;
if (v !=null) {
old.value = v;
afterNodeAccess(old);
}
else removeNode(hash, key, null, false, true);
return v;
}
if (value !=null) {
if (t !=null)
t.putTreeVal(this, tab, hash, key, value);
else {
tab[i] = newNode(hash, key, value, first);
if (binCount >=TREEIFY_THRESHOLD -1)
treeifyBin(tab, hash);
}
++modCount;
++size;
afterNodeInsertion(true);
}
return value;
}
遍历
public void forEach(BiConsumer<? super K, ? super V> action) {
Node[] 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)
throw new ConcurrentModificationException();
}
}
替换所有
public void replaceAll(BiFunction<? super K, ? super V> function) {
Node<K,V>[] tab;
if (function ==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) {
e.value = function.apply(e.key, e.value);
}
}
if (modCount != mc)
throw new ConcurrentModificationException();
}
}
Returns a shallow copy (浅副本，key和Value不被克隆)
@SuppressWarnings("unchecked")
public Object clone() {
HashMap result;
try {
result = (HashMap)super.clone();
}catch (CloneNotSupportedException e) {
throw new InternalError(e);
}
result.reinitialize();
result.putMapEntries(this, false);
return result;
}
final float loadFactor() {return loadFactor; }
final int capacity() {
return (table !=null) ?table.length :
(threshold >0) ?threshold : DEFAULT_INITIAL_CAPACITY;
}
Save the state of the HashMap instance to a stream (i.e.,
private void writeObject(java.io.ObjectOutputStream s)throws IOException {
int buckets = capacity();
// Write out the threshold, loadfactor, and any hidden stuff
s.defaultWriteObject();
s.writeInt(buckets);//容量
s.writeInt(size);//长度
internalWriteEntries(s);
}
private void readObject(java.io.ObjectInputStream s)throws IOException, ClassNotFoundException {
// Read in the threshold (ignored), loadfactor, and any hidden stuff
s.defaultReadObject();
reinitialize();
if (loadFactor <=0 || Float.isNaN(loadFactor))
throw new InvalidObjectException("Illegal load factor: " +loadFactor);
s.readInt(); // Read and ignore number of buckets
int mappings = s.readInt(); // Read number of mappings (size)
if (mappings <0)
throw new InvalidObjectException("Illegal mappings count: " +mappings);
else if (mappings >0) {// (if zero, use defaults)
// Size the table using given load factor only if within
// range of 0.25...4.0
float lf = Math.min(Math.max(0.25f, loadFactor), 4.0f);
float fc = (float)mappings / lf +1.0f;
int cap = ((fc<DEFAULT_INITIAL_CAPACITY) ?DEFAULT_INITIAL_CAPACITY :
(fc >=MAXIMUM_CAPACITY) ?MAXIMUM_CAPACITY :tableSizeFor((int)fc));
float ft = (float)cap * lf;
threshold = ((cap< MAXIMUM_CAPACITY && ft<MAXIMUM_CAPACITY) ?
(int)ft : Integer.MAX_VALUE);
@SuppressWarnings({"rawtypes","unchecked"})
Node<K,V>[] tab = (Node<K,V>[])new Node[cap];
table = tab;
// Read the keys and values, and put the mappings in the HashMap
for (int i =0; i < mappings; i++) {
@SuppressWarnings("unchecked")
K key = (K) s.readObject();
@SuppressWarnings("unchecked")
V value = (V) s.readObject();
putVal(hash(key), key, value, false, false);
}
}
}
HashIterator
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(); }
}
可并行迭代器
static class HashMapSpliterator {
final HashMap<K,V> map;
Node<K,V> current; // current node
int index; // current index, modified on advance/split
int fence; // one past last index
int est; // size estimate
int expectedModCount; // for comodification checks
HashMapSpliterator(HashMap<K,V> m, int origin,
int fence, int est,
int expectedModCount) {
this.map = m;
this.index = origin;
this.fence = fence;
this.est = est;
this.expectedModCount = expectedModCount;
}
final int getFence() {// initialize fence and size on first use
int hi;
if ((hi =fence) <0) {
HashMap<K,V> m =map;
est = m.size;
expectedModCount = m.modCount;
Node<K,V>[] tab = m.table;
hi =fence = (tab ==null) ?0 : tab.length;
}
return hi;
}
public final long estimateSize() {
getFence(); // force init
return (long)est;
}
}
static final class KeySpliterator<K,V> extends HashMapSpliterator<K,V> implements Spliterator<K> {
KeySpliterator(HashMap<K,V> m, int origin, int fence, int est, int expectedModCount) {
super(m, origin, fence, est, expectedModCount);
}
public KeySpliterator<K,V> trySplit() {
int hi = getFence(), lo =index, mid = (lo + hi) >>>1;
return (lo >= mid ||current !=null) ?null :
new KeySpliterator<>(map, lo, index = mid, est >>>=1,
expectedModCount);
}
public void forEachRemaining(Consumer<? super K> action) {
int i, hi, mc;
if (action ==null)
throw new NullPointerException();
HashMap<K,V> m =map;
Node<K,V>[] tab = m.table;
if ((hi =fence) <0) {
mc =expectedModCount = m.modCount;
hi =fence = (tab ==null) ?0 : tab.length;
}
else
mc =expectedModCount;
if (tab !=null && tab.length >= hi &&
(i =index) >=0 && (i < (index = hi) ||current !=null)) {
Node<K,V> p =current;
current =null;
do {
if (p ==null)
p = tab[i++];
else {
action.accept(p.key);
p = p.next;
}
}while (p !=null || i < hi);
if (m.modCount != mc)
throw new ConcurrentModificationException();
}
}
public boolean tryAdvance(Consumer<? super K> action) {
int hi;
if (action ==null)
throw new NullPointerException();
Node<K,V>[] tab =map.table;
if (tab !=null && tab.length >= (hi = getFence()) &&index >=0) {
while (current !=null ||index < hi) {
if (current ==null)
current = tab[index++];
else {
K k =current.key;
current =current.next;
action.accept(k);
if (map.modCount !=expectedModCount)
throw new ConcurrentModificationException();
return true;
}
}
}
return false;
}
public int characteristics() {
return (fence <0 ||est ==map.size ? Spliterator.SIZED :0) | Spliterator.DISTINCT;
}
}
static final class ValueSpliterator<K,V> extends HashMapSpliterator<K,V>
implements Spliterator<V> {
ValueSpliterator(HashMap<K,V> m, int origin, int fence, int est,
int expectedModCount) {
super(m, origin, fence, est, expectedModCount);
}
public ValueSpliterator<K,V> trySplit() {
int hi = getFence(), lo =index, mid = (lo + hi) >>>1;
return (lo >= mid ||current !=null) ?null :
new ValueSpliterator<>(map, lo, index = mid, est >>>=1,
expectedModCount);
}
public void forEachRemaining(Consumer<? super V> action) {
int i, hi, mc;
if (action ==null)
throw new NullPointerException();
HashMap<K,V> m =map;
Node<K,V>[] tab = m.table;
if ((hi =fence) <0) {
mc =expectedModCount = m.modCount;
hi =fence = (tab ==null) ?0 : tab.length;
}
else
mc =expectedModCount;
if (tab !=null && tab.length >= hi &&
(i =index) >=0 && (i < (index = hi) ||current !=null)) {
Node<K,V> p =current;
current =null;
do {
if (p ==null)
p = tab[i++];
else {
action.accept(p.value);
p = p.next;
}
}while (p !=null || i < hi);
if (m.modCount != mc)
throw new ConcurrentModificationException();
}
}
public boolean tryAdvance(Consumer<? super V> action) {
int hi;
if (action ==null)
throw new NullPointerException();
Node[] tab =map.table;
if (tab !=null && tab.length >= (hi = getFence()) &&index >=0) {
while (current !=null ||index < hi) {
if (current ==null)
current = tab[index++];
else {
V v =current.value;
current =current.next;
action.accept(v);
if (map.modCount !=expectedModCount)
throw new ConcurrentModificationException();
return true;
}
}
}
return false;
}
public int characteristics() {
return (fence <0 ||est ==map.size ? Spliterator.SIZED :0);
}
}
static final class EntrySpliterator<K,V>extends HashMapSpliterator<K,V>
implements Spliterator<K,V> {
EntrySpliterator(HashMap<K,V> m, int origin, int fence, int est,
int expectedModCount) {
super(m, origin, fence, est, expectedModCount);
}
public EntrySpliterator<K,V> trySplit() {
int hi = getFence(), lo =index, mid = (lo + hi) >>>1;
return (lo >= mid ||current !=null) ?null :
new EntrySpliterator<>(map, lo, index = mid, est >>>=1, expectedModCount);
}
public void forEachRemaining(Consumer<? super Map.Entry<K,V> action) {
int i, hi, mc;
if (action ==null)
throw new NullPointerException();
HashMap<K,V> m =map;
Node<K,V>[] tab = m.table;
if ((hi =fence) <0) {
mc =expectedModCount = m.modCount;
hi =fence = (tab ==null) ?0 : tab.length;
}
else
mc =expectedModCount;
if (tab !=null && tab.length >= hi &&(i =index) >=0
&& (i < (index = hi) ||current !=null)) {
Node<K,V> p =current;
current =null;
do {
if (p ==null)
p = tab[i++];
else {
action.accept(p);
p = p.next;
}
}while (p !=null || i < hi);
if (m.modCount != mc)
throw new ConcurrentModificationException();
}
}
public boolean tryAdvance(Consumer<? super Map<K,V>> action) {
int hi;
if (action ==null)
throw new NullPointerException();
Node<K,V>[] tab =map.table;
if (tab !=null && tab.length >= (hi = getFence()) &&index >=0) {
while (current !=null ||index < hi) {
if (current ==null)
current = tab[index++];
else {
Node<K,V> e =current;
current =current.next;
action.accept(e);
if (map.modCount !=expectedModCount)
throw new ConcurrentModificationException();
return true;
}
}
}
return false;
}
public int characteristics() {
return (fence <0 ||est ==map.size ? Spliterator.SIZED :0) | Spliterator.DISTINCT;
}
}
Node<K,V> newNode(int hash, K key, V value, Node<K,V> next) {
return new Node<>(hash, key, value, next);
}
Node<K,V> replacementNode(Node<K,V> p, Node next) {
return new Node<>(p.hash, p.key, p.value, next);
}
TreeNode<K,V> newTreeNode(int hash, K key, V value, Node<K,V> next) {
return new TreeNode<>(hash, key, value, next);
}
TreeNode<K,V> replacementTreeNode(Node<K,V> p, Node<K,V> next) {
return new TreeNode<>(p.hash, p.key, p.value, next);
}
void reinitialize() {
table =null;
entrySet =null;
keySet =null;
values =null;
modCount =0;
threshold =0;
size =0;
}
回调函数
void afterNodeAccess(Node<K,V> p) { }
void afterNodeInsertion(boolean evict) { }
void afterNodeRemoval(Node<K,V> p) { }
// Called only from writeObject, to ensure compatible ordering.
void internalWriteEntries(java.io.ObjectOutputStream s)throws IOException {
Node<K,V>[] tab;
if (size >0 && (tab =table) !=null) {
for (int i =0; i < tab.length; ++i) {
for (Node e = tab[i]; e !=null; e = e.next) {
s.writeObject(e.key);
s.writeObject(e.value);
}
}
}
}
红黑树
static final class TreeNodeextends LinkedHashMap.Entry {
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);
}
//返回跟节点
final TreeNoderoot() {
for (TreeNode r =this, p;;) {
if ((p = r.parent) ==null) return r;
r = p;
}
}
//确保给定的根是它的bin的第一个节点。
static 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);
}
}
//在树中查找某个节点
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;
}
//按照hashCode和Key查找
final TreeNodegetTreeNode(int h, Object k) {
return ((parent !=null) ? root() :this).find(h, k, null);
}
//tieBreakOrder()方法最终还是通过调用System.identityHashCode()方法来比较。
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;
}
//将链表转化为树
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);
}
//将树转化为链表,返回头节点
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;
}
//树版的插入操作
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 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;
}
}
}
//删除树的节点
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);
}
//拆分树
final void split(HashMap map, Node[] tab, int index, int bit) {
TreeNode b =this;
// Relink into lo and hi lists, preserving order
TreeNode loHead =null, loTail =null;
TreeNode hiHead =null, hiTail =null;
int lc =0, hc =0;
for (TreeNode e = b, next; e !=null; e = next) {
next = (TreeNode)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);
}
}
}
//红黑树平衡方法
//左旋
static<K,V> TreeNode<K,V> rotateLeft(TreeNode<K,V> root, TreeNode<K,V> p) {
TreeNode 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;
}
//右旋
static TreeNode rotateRight(TreeNode root,TreeNode p) {
TreeNode 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;
}
//平衡
static TreeNode balanceInsertion(TreeNode root, TreeNode x) {
x.red =true;
for (TreeNode 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 TreeNode balanceDeletion(TreeNode root, TreeNode x) {
for (TreeNode 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 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 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;
}
}
}
}
}
//递归不变检查，检测稳定性
static boolean checkInvariants(TreeNode t) {
TreeNode tp = t.parent, tl = t.left, tr = t.right,
tb = t.prev, tn = (TreeNode)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;
}
}
}
