SimpleHashMap的部分抄袭解释

package com.zzc.common.utils;import lombok.extern.slf4j.Slf4j;import java.io.IOException;
import java.io.Serializable;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.AbstractCollection;
import java.util.AbstractMap;
import java.util.AbstractSet;
import java.util.Collection;
import java.util.ConcurrentModificationException;
import java.util.Iterator;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Objects;
import java.util.Set;
import java.util.Spliterator;
import java.util.function.Consumer;@Slf4j
public class SimpleHashMap<K, V> extends AbstractMap<K, V> implements Map<K, V>, Cloneable, Serializable {private static final long serialVersionUID = 362498820763181265L;/*** 默认初始容量为 16，必须是2的幂次方*/static final int DEFAULT_INITIAL_CAPACITY = 1 << 4; // aka 16/*** 最大容量，当任一带参数的构造函数参数指定了更高的值时使用，区间 2的幂次方 <= 2的30次方*/static final int MAXIMUM_CAPACITY = 1 << 30;/*** 在构造函数中未指定时使用的负载因子* <p>* HashMap的负载因子默认设置为0.75是为了在保证空间利用率的同时，尽可能减少‌哈希冲突的发生，从而提高HashMap的性能。这个设置是基于以下考虑：* 1:平衡性能和空间利用率：设置负载因子为0.75可以在哈希表填充到一定程度时触发扩容操作，避免链表过长导致的查询效率下降，同时减少因频繁扩容带来的性能损耗。* 2:理论依据：这个值也基于‌泊松分布的理论计算得出，经过实验验证，0.75的负载因子在大多数情况下能提供较好的性能表现。* 3:实践应用：在实际应用中，0.75的负载因子能够有效地减少哈希冲突，同时保持较高的空间利用率，避免浪费存储空间。* 综上所述，0.75的负载因子是经过理论和实验验证的一个优化选择，旨在平衡HashMap的性能和空间效率。*/static final float DEFAULT_LOAD_FACTOR = 0.75f;/*** 使用树数据结构存储，而不是数组作为存储的数据量大小* 单个node节点下的子节点数量大于8时，就会由链表转为红黑树* 该值必须大于2并且至少应该为8，*/static final int TREEIFY_THRESHOLD = 8;/*** 单个node节点下的子节点数量小于6时，则会由红黑树结构转换为链表结构*/static final int UNTREEIFY_THRESHOLD = 6;/*** 将列表树化的最小容量* （如果容器中节点太多，则调整容器的大小）* 每次扩容，应该至少4*TREEIFY_THRESHOLD的大小，以避免调整大小和树化阈值之间的冲突** 当链表长度大于等于TREEIFY_THRESHOLD - 1，并且数组长度大于等于MIN_TREEIFY_CAPACITY是就会转红黑树*/static final int MIN_TREEIFY_CAPACITY = 64;transient Set<K>        keySet;transient Collection<V> values;/*** 该表在首次使用时进行初始化，并根据需要调整大小。当分配时，长度总是2的幂。* （在某些操作中，我们还允许长度为零，以允许目前不需要的引导机制。）*/transient Node<K, V>[] table;/*** 保存缓存的entrySet（）。请注意，AbstractMap字段用于keySet（）和values（）。*/transient Set<Map.Entry<K, V>> entrySet;/*** 节点数量*/transient int size;/*** 用于快速失败机制* 该参数表示hashmap数据修改的次数或者其他内部修改次数（比如：rehash）* HashMap 的 Fail-Fast 机制是 Java 集合框架中的一种错误检测机制。* 当多个线程对某个集合进行结构上的改变操作时，若有其他线程在该集合上进行遍历操作，则可能会抛出 ConcurrentModificationException 异常。* Fail-Fast 机制并不保证多线程环境下的正确性，它只是尽可能地检测出并发修改的问题。*/transient int modCount;/*** 扩容阀值* 下一个要调整大小的大小值（容量*负载系数）。*/// (The javadoc description is true upon serialization.// Additionally, if the table array has not been allocated, this// field holds the initial array capacity, or zero signifying// DEFAULT_INITIAL_CAPACITY.)int threshold;/*** 哈希表的负载系数*/final float loadFactor;//--------------/*** 初始化hashMap** @param initialCapacity 初始化大小* @param loadFactor*/public SimpleHashMap(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);//处理为2的次方大小}public SimpleHashMap(int initialCapacity) {this(initialCapacity, DEFAULT_LOAD_FACTOR);}public SimpleHashMap() {this.loadFactor = DEFAULT_LOAD_FACTOR; // all other fields defaulted}/*** @param m*/public SimpleHashMap(Map<? extends K, ? extends V> m) {this.loadFactor = DEFAULT_LOAD_FACTOR;//使用默认负载因子putMapEntries(m, false);}/*** @param map* @param evict 最初构建此映射时为false，否则为true（在NodeInsertion后中继到方法）*/final void putMapEntries(Map<? extends K, ? extends V> map, boolean evict) {int s = map.size();if (s > 0) {if (table == null) { // pre-size 如果前置节点为空，则代表容器需要float ft = ((float) s / loadFactor) + 1.0F;//int t = ((ft < (float) MAXIMUM_CAPACITY) ? (int) ft : MAXIMUM_CAPACITY);//if (t > threshold) // 容器大小threshold = tableSizeFor(t);//需要调整容器大小的阀值} else {// Because of linked-list bucket constraints, we cannot// expand all at once, but can reduce total resize// effort by repeated doubling now vs laterwhile (s > threshold && table.length < MAXIMUM_CAPACITY)resize();}for (Map.Entry<? extends K, ? extends V> e : map.entrySet()) {K key = e.getKey();V value = e.getValue();putVal(hash(key), key, value, false, evict);}}}/*** @return the number of key-value mappings in this map*/public int size() {return size;}/****/public boolean isEmpty() {return size == 0;}/*** 返回指定键映射到的值，如果map的key为null或者vall为null则返回null** @see #put(Object, Object)*/public V get(Object key) {Node<K, V> e;return (e = getNode(key)) == null ? null : e.value;}/*** 判断key是否存在** @param key key whose presence in this map is to be tested* @return*/public boolean containsKey(Object key) {return getNode(key) != null;}public V put(K key, V value) {return putVal(hash(key), key, value, false, true);}/*** 计算key.hashCode（）并将哈希的高位扩展（XORs）到低位。* 由于该表使用了两个掩码的能力，因此仅在当前掩码以上的位上变化的哈希集总是会发生冲突。（已知的例子包括在小表中保存连续整数的浮点键集。）* 因此，我们应用了一种变换，将高位的影响向下分散。比特扩展的速度、效用和质量之间存在权衡。* 由于许多常见的哈希集已经合理分布（因此不会从扩展中受益），并且由于我们使用树来处理容器中的大量冲突，* 我们只需以最便宜的方式XOR一些移位的比特，以减少系统损失，并考虑由于表边界而永远不会在索引计算中使用的最高比特的影响。** 首先获取对象的hashCode()值，然后将hashCode值右移16位，然后将右移后的值与原来的hashCode做异或运算，返回结果。（其中h>>>16，在JDK1.8中，优化了高位运算的算法，使用了零扩展，无论正数还是负数，都在高位插入0）。* 在 putVal 源码中，我们通过(n-1)&hash获取该对象的键在hashmap中的位置。其中n表示的是hash桶数组的长度，并且该长度为2的n次方，这样(n-1)&hash就等价于hash%n。因为&运算的效率高于%运算。* @param key* @return*/static final int hash(Object key) {int h;return (key == null) ? 0 : (h = key.hashCode()) ^ (h >>> 16);//将高16位移到低16位，高位补0}/*** TODO* 将key传进来判断是否实现了Comparable接口* @param x* @return*/static Class<?> comparableClassFor(Object x) {if (x instanceof Comparable) {//判断x是否实现了Comparable接口Class<?> c;Type[] ts, as;ParameterizedType p;if ((c = x.getClass()) == String.class) // 校验x是否为String类型return c;if ((ts = c.getGenericInterfaces()) != null) {//存在实现的接口for (Type t : ts) {//遍历x实现的所有接口if ((t instanceof ParameterizedType) &&((p = (ParameterizedType) t).getRawType() ==Comparable.class) &&(as = p.getActualTypeArguments()) != null &&as.length == 1 && as[0] == c) // 如果x实现了Comparable接口，则返回x的Classreturn c;}}}return null;}/** Returns k.compareTo(x) if x matches kc (k's screened comparable* class), else 0.*/@SuppressWarnings({"rawtypes", "unchecked"}) // for cast to Comparablestatic int compareComparables(Class<?> kc, Object k, Object x) {return (x == null || x.getClass() != kc ? 0 :((Comparable) k).compareTo(x));}/*** 返回给定目标容量的2次幂* 为什么要2的次方：* 因为获取 key 在数组中对应的下标是通过 key 的哈希值与 数组长度-1 进行与运算，如：i = (n - 1) & hash* 1、n 为 2 的整数次幂，这样 n-1 后之前为 1 的位后面全是 1，这样就能保证 (n-1) & hash 后相应的位数既可能是 0 又可能是 1，这取决于 hash 的值，这样能保证散列的均匀，同时与运算效率高* 2、如果 n 不是 2 的整数次幂，会造成更多的 hash 冲突** @param cap* @return*/static final int tableSizeFor(int cap) {// 首先在jvm中一个int类型的数据占4个字节，共32位，其实就相当于一个长度为32的数组。// 那我们要计算高位连续0的个数，就是从左边第一个位开始累加0的个数，直到遇到一个非零值// 例：cap=3；// 过程：2的二进制 0000 0000 0000 0000 0000 0000 0000 0010， numberOfLeadingZeros 之后等于30位，-1的二进制 1000 0000 0000 0000 0000 0000 0000 0000int n = -1 >>> Integer.numberOfLeadingZeros(cap - 1);//cap - 1 应该时避免int最大值，2^32-1 这个原因吧；-1的二进制友移30位 0000 0000 0000 0000 0000 0000 0000 0011 得到该值return (n < 0) ? 1 : (n >= MAXIMUM_CAPACITY) ? MAXIMUM_CAPACITY : n + 1;//最终结果 2^2=4}/*** 获取节点* @param key* @return*/final Node<K, V> getNode(Object key) {Node<K, V>[] tab;Node<K, V> first, e;int n, hash;K k;// 对table进行效验 ：table不为空 && table长度大于0 &&// table索引位置(使用table.length-1 和hash值进行位与计算)if ((tab = table) != null && (n = tab.length) > 0 &&(first = tab[(n - 1) & (hash = hash(key))]) != null) {//如果表不等于null并且表大小大于0，并且第一个节点的if (first.hash == hash && // always check first node((k = first.key) == key || (key != null && key.equals(k))))//检查first节点的hash值和key是否入参的一样,如果一样则first即为目标节点，直接返回first节点return first;if ((e = first.next) != null) {//如果first不是目标节点，并且first的next节点e不为空则继续遍历if (first instanceof TreeNode)//如果是红黑树节点，则调用红黑树的查找目标节点方法getTreeNodereturn ((TreeNode<K, V>) first).getTreeNode(hash, key);do {if (e.hash == hash &&((k = e.key) == key || (key != null && key.equals(k))))//执行链表节点的查找，向下遍历链表, 直至找到节点的key和入参的key相等时,返回该节点return e;} while ((e = e.next) != null);}}return null;}/*** 数组+链表+红黑树* @param hash* @param key* @param value* @param onlyIfAbsent* @param evict* @return*/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)//校验table是否为空或者length等于0，如果是则调用resize方法进行初始化tablen = (tab = resize()).length;//resize()方法 扩容之后返回一个新的Node[]数组,n为数组tab的长度if ((p = tab[i = (n - 1) & hash]) == null)//通过hash值计算索引位置，将该索引位置的头节点赋值给p，如果p为空则直接在该索引位置新增一个节点即可tab[i] = newNode(hash, key, value, null);//newNode()方法 链表的头结点else {//否则进行hash key 的对比Node<K, V> e;K k;if (p.hash == hash &&((k = p.key) == key || (key != null && key.equals(k))))//table表该索引位置不为空，则进行查找 p是头结点e = p;else if (p instanceof TreeNode)//判断p节点是否为TreeNode, 如果是则调用红黑树的putTreeVal方法查找目标节点e = ((TreeNode<K, V>) p).putTreeVal(this, tab, hash, key, value);//将键值对存入红黑树中 putTreeVal()else {//走到这代表p节点为普通链表节点，则调用普通的链表方法进行查找，使用binCount统计链表的节点数for (int binCount = 0; ; ++binCount) {if ((e = p.next) == null) {//当遍历到链表为空的时候p.next = newNode(hash, key, value, null);//hashmap中在链表的末尾创建新的节点,linkedhashMap重写了newNode节点 转为双向链表if (binCount >= TREEIFY_THRESHOLD - 1) // 校验节点数是否超过8个，如果超过则调用treeifyBin方法将链表节点转为红黑树节点，,减一是因为循环是从p节点的下一个节点开始的treeifyBin(tab, hash);//链表转红黑树treeifyBin()break;}if (e.hash == hash &&((k = e.key) == key || (key != null && key.equals(k))))//如果e节点存在hash值和key值都与传入的相同，则e节点即为目标节点，跳出循环break;p = e;//将p指向下一个节点}}if (e != null) { // 如果e节点不为空，则代表目标节点存在，使用传入的value覆盖该节点的value，并返回oldValueV oldValue = e.value;if (!onlyIfAbsent || oldValue == null)e.value = value;afterNodeAccess(e);return oldValue;}}++modCount;if (++size > threshold)//如果插入节点后节点数超过阈值，则调用resize方法进行扩容resize();//扩容afterNodeInsertion(evict);//用于LinkedHashMapreturn null;}/*** 初始化或加倍表的大小。* 如果为空，则按照字段阈值中持有的初始容量目标分配。否则，因为我们使用的是2的幂展开，所以每个容器中的元素必须保持在相同的索引，或者在新表中以2的偏移量幂移动。* @return*/final Node<K, V>[] resize() {Node<K, V>[] oldTab = table;//定义old变量，保留old变量int oldCap = (oldTab == null) ? 0 : oldTab.length;//当前old节点的的hash表节点数量int oldThr = threshold;//old负载因子，扩容阀值int newCap, newThr = 0;//初始化新的数组大小和新的负载因子if (oldCap > 0) {//当old hash表节点不为空，即数量大于0if (oldCap >= MAXIMUM_CAPACITY) {//当前的hash表大与最大容量限制，则不进行扩容threshold = Integer.MAX_VALUE;//扩展阀值设置为int最大值return oldTab;//不扩容，返回旧的hash表} else if ((newCap = oldCap << 1) < MAXIMUM_CAPACITY &&oldCap >= DEFAULT_INITIAL_CAPACITY)//如果扩容2倍并且小于最大容量，并且大于初始化容量newThr = oldThr << 1; // （新容量*负载因子）扩展阀值扩大2倍} else if (oldThr > 0) // hash为空，扩容阀值大与0，则扩容后hash表大小等与该阀值newCap = oldThr;else {//当hash为空，则使用默认值newCap = DEFAULT_INITIAL_CAPACITY;//初始化hash表大小为 16newThr = (int) (DEFAULT_LOAD_FACTOR * DEFAULT_INITIAL_CAPACITY);//初始化扩容阀值为12}if (newThr == 0) {//hash为空，扩容阀值大与0，赋值完newCap后，重新计算扩容阀值float ft = (float) newCap * loadFactor;newThr = (newCap < MAXIMUM_CAPACITY && ft < (float) MAXIMUM_CAPACITY ?(int) ft : Integer.MAX_VALUE);}threshold = newThr;//设置全局变量 扩容阀值//初始化新的hash表，若旧的hash表存在数据，则进行迁移@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) {//如果当前节点不为空oldTab[j] = null;if (e.next == null)//如果当前节点的next指向下一个节点为空，则同一层级的数组newTab[e.hash & (newCap - 1)] = e;else if (e instanceof TreeNode)//如果当前节点的next指向下一个节点不为空，节点为树节点((TreeNode<K, V>) e).split(this, newTab, j, oldCap);else { // 如果是普通的链表节点，则进行普通的重hash分布Node<K, V> loHead = null, loTail = null;Node<K, V> hiHead = null, hiTail = null;Node<K, V> next;do {//完成遍历后，可能会得到两条链表next = e.next;if ((e.hash & oldCap) == 0) {//如果e的hash值与旧表的容量进行与运算为0,则扩容后的索引位置跟旧表的索引位置一样if (loTail == null)//如果loTail为空, 代表该节点为第一个节点loHead = e;//则将loHead赋值为第一个节点else//否则将节点添加在loTail后面loTail.next = e;//loTail = e;//并将loTail赋值为新增的节点} else {//如果e的hash值与旧表的容量进行与运算为非0,则扩容后的索引位置为:旧表的索引位置＋oldCapif (hiTail == null)//如果hiTail为空, 代表该节点为第一个节点hiHead = e;//则将hiHead赋值为第一个节点else//否则将节点添加在hiTail后面hiTail.next = e;hiTail = e;//并将hiTail赋值为新增的节点}} while ((e = next) != null);if (loTail != null) {//如果loTail不为空（说明旧表的数据有分布到新表上“原索引位置”的节点），则将最后一个节点的next设为空，并将新表上索引位置为“原索引位置”的节点设置为对应的头节点loTail.next = null;newTab[j] = loHead;}if (hiTail != null) {//如果hiTail不为空（说明旧表的数据有分布到新表上“原索引+oldCap位置”的节点），则将最后一个节点的next设为空，并将新表上索引位置为“原索引+oldCap”的节点设置为对应的头节点hiTail.next = null;newTab[j + oldCap] = hiHead;}}}}}return newTab;//返回新的table}/*** 将链表转为红黑树节点* @param tab* @param hash*/final void treeifyBin(Node<K, V>[] tab, int hash) {int n, index;Node<K, V> e;//如果table为空或者table的长度小于64, 调用resize方法进行扩容if (tab == null || (n = tab.length) < MIN_TREEIFY_CAPACITY)resize();else if ((e = tab[index = (n - 1) & hash]) != null) {//根据hash值计算索引值，将该索引位置的节点赋值给e，从e开始遍历该索引位置的链表TreeNode<K, V> hd = null, tl = null;do {//将链表节点转红黑树节点TreeNode<K, V> p = replacementTreeNode(e, null);//将Node节点转为TreeNode节点if (tl == null)//如果是第一次遍历，将头节点赋值给hd，tl为空代表为第一次循环hd = p;else {//如果不是第一次遍历，则处理当前节点的prev属性和上一个节点的next属性p.prev = tl;tl.next = p;}tl = p;//将p节点赋值给tl，用于在下一次循环中作为上一个节点进行一些链表的关联操作（p.prev = tl 和 tl.next = p）} while ((e = e.next) != null);if ((tab[index] = hd) != null)//将table该索引位置赋值为新转的TreeNode的头节点，如果该节点不为空，则以以头节点(hd)为根节点, 构建红黑树treeify()hd.treeify(tab);//treeify()使用数组tab[Node<key,value>] 构建红黑树}}public void putAll(Map<? extends K, ? extends V> m) {putMapEntries(m, true);}/*** Removes the mapping for the specified key from this map if present.** @param key key whose mapping is to be removed from the map* @return the previous value associated with {@code key}, or* {@code null} if there was no mapping for {@code key}.* (A {@code null} return can also indicate that the map* previously associated {@code null} with {@code key}.)*/public V remove(Object key) {Node<K, V> e;return (e = removeNode(hash(key), key, null, false, true)) == null ?null : e.value;}/*** 删除节点* @param hash* @param key* @param value* @param matchValue* @param movable* @return*/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) {//如果table不为空并且根据hash值计算出来的索引位置不为空, 将该位置的节点赋值给pNode<K, V> node = null, e;K k;V v;if (p.hash == hash &&((k = p.key) == key || (key != null && key.equals(k))))//如果p的hash值和key都与入参的相同, 则p即为目标节点, 赋值给nodenode = p;//else if ((e = p.next) != null) {//否则将p.next赋值给e，向下遍历节点if (p instanceof TreeNode)//如果p是TreeNode则调用红黑树的方法查找节点node = ((TreeNode<K, V>) p).getTreeNode(hash, key);else {//否则，进行普通链表节点的查找do {if (e.hash == hash &&((k = e.key) == key ||(key != null && key.equals(k)))) {//当节点的hash值和key与传入的相同,则该节点即为目标节点node = e;break;}p = e;} while ((e = e.next) != null);}}//对节点下的链表或者树节点中的节点进行移除if (node != null && (!matchValue || (v = node.value) == value ||(value != null && value.equals(v)))) {//如果node不为空(即根据传入key和hash值查找到目标节点)，则进行移除操作if (node instanceof TreeNode)// 如果是TreeNode则调用红黑树的移除方法((TreeNode<K, V>) node).removeTreeNode(this, tab, movable);else if (node == p)//如果node是该索引位置的头节点则直接将该索引位置的值赋值为node的next节点，“node == p”只会出现在node是头节点的时候，如果node不是头节点，则node为p的next节点tab[index] = node.next;else//否则将node的上一个节点的next属性设置为node的next节点,即将node节点移除, 将node的上下节点进行关联(链表的移除)p.next = node.next;++modCount;--size;afterNodeRemoval(node);return node;}}return null;}/*** Removes all of the mappings from this map.* The map will be empty after this call returns.*/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;}}/*** Returns {@code true} if this map maps one or more keys to the* specified value.** @param value value whose presence in this map is to be tested* @return {@code true} if this map maps one or more keys to the* specified value*/public boolean containsValue(Object value) {Node<K, V>[] tab;V v;if ((tab = table) != null && size > 0) {for (Node<K, V> e : tab) {for (; e != null; e = e.next) {if ((v = e.value) == value ||(value != null && value.equals(v)))return true;}}}return false;}/*** 覆写抽象的keySet* @return*/@Overridepublic Set<K> keySet() {Set<K> ks = keySet;if (ks == null) {ks = new KeySet();keySet = ks;}return ks;}@Overridepublic Collection<V> values() {Collection<V> vs = values;if (vs == null) {vs = new Values();values = vs;}return vs;}/* ------------------------------------------------------------ */// LinkedHashMap support/** The following package-protected methods are designed to be* overridden by LinkedHashMap, but not by any other subclass.* Nearly all other internal methods are also package-protected* but are declared final, so can be used by LinkedHashMap, view* classes, and HashSet.*/// Create a regular (non-tree) nodeNode<K, V> newNode(int hash, K key, V value, Node<K, V> next) {return new Node<>(hash, key, value, next);}// For conversion from TreeNodes to plain nodesNode<K, V> replacementNode(Node<K, V> p, Node<K, V> next) {return new Node<>(p.hash, p.key, p.value, next);}// Create a tree bin nodeTreeNode<K, V> newTreeNode(int hash, K key, V value, Node<K, V> next) {return new TreeNode<>(hash, key, value, next);}// For treeifyBinTreeNode<K, V> replacementTreeNode(Node<K, V> p, Node<K, V> next) {return new TreeNode<>(p.hash, p.key, p.value, next);}/*** Reset to initial default state.  Called by clone and readObject.*/void reinitialize() {table = null;entrySet = null;keySet = null;values = null;modCount = 0;threshold = 0;size = 0;}// Callbacks to allow LinkedHashMap post-actionsvoid 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 (Node<K, V> e : tab) {for (; e != null; e = e.next) {s.writeObject(e.key);s.writeObject(e.value);}}}}@Overridepublic Set<Map.Entry<K, V>> entrySet() {Set<Map.Entry<K, V>> es;return (es = entrySet) == null ? (entrySet = new EntrySet()) : es;}final class Values extends AbstractCollection<V> {public final int size()                 { return size; }public final void clear()               { 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<>(SimpleHashMap.this, 0, -1, 0, 0);}public Object[] toArray() {return valuesToArray(new Object[size]);}public <T> T[] toArray(T[] a) {return valuesToArray(prepareArray(a));}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 (Node<K,V> e : tab) {for (; e != null; e = e.next)action.accept(e.value);}if (modCount != mc)throw new ConcurrentModificationException();}}}static final class ValueSpliterator<K,V>extends HashMapSpliterator<K,V>implements Spliterator<V> {ValueSpliterator(SimpleHashMap<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();SimpleHashMap<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;}elsemc = 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<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 {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);}}final class KeySet extends AbstractSet<K> {public final int size() {return size;}public final void clear() {SimpleHashMap.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<>(SimpleHashMap.this, 0, -1, 0, 0);}public Object[] toArray() {return keysToArray(new Object[size]);}public <T> T[] toArray(T[] a) {return keysToArray(prepareArray(a));}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 (Node<K, V> e : tab) {for (; e != null; e = e.next)action.accept(e.key);}if (modCount != mc)throw new ConcurrentModificationException();}}}@SuppressWarnings("unchecked")final <T> T[] prepareArray(T[] a) {int size = this.size;if (a.length < size) {return (T[]) java.lang.reflect.Array.newInstance(a.getClass().getComponentType(), size);}if (a.length > size) {a[size] = null;}return a;}/*** Fills an array with this map keys and returns it. This method assumes* that input array is big enough to fit all the keys. Use* {@link #prepareArray(Object[])} to ensure this.** @param a   an array to fill* @param <T> type of array elements* @return supplied array*/<T> T[] keysToArray(T[] a) {Object[] r = a;Node<K, V>[] tab;int idx = 0;if (size > 0 && (tab = table) != null) {for (Node<K, V> e : tab) {for (; e != null; e = e.next) {r[idx++] = e.key;}}}return a;}/*** Fills an array with this map values and returns it. This method assumes* that input array is big enough to fit all the values. Use* {@link #prepareArray(Object[])} to ensure this.** @param a   an array to fill* @param <T> type of array elements* @return supplied array*/<T> T[] valuesToArray(T[] a) {Object[] r = a;Node<K, V>[] tab;int idx = 0;if (size > 0 && (tab = table) != null) {for (Node<K, V> e : tab) {for (; e != null; e = e.next) {r[idx++] = e.value;}}}return a;}static final class KeySpliterator<K, V>extends HashMapSpliterator<K, V>implements Spliterator<K> {KeySpliterator(SimpleHashMap<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();SimpleHashMap<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;} elsemc = 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;}}/*** node节点，作为基本hash节点** @param <K>* @param <V>*/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;// Map.Entry<?, ?> e 写法jdk8不支持，jdk17支持/*return o instanceof Map.Entry<?, ?> e&& Objects.equals(key, e.getKey())&& Objects.equals(value, e.getValue());*/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;}}static class Entry<K, V> extends Node<K, V> {Entry<K, V> before, after;Entry(int hash, K key, V value, Node<K, V> next) {super(hash, key, value, next);}}static final class EntrySpliterator<K, V>extends HashMapSpliterator<K, V>implements Spliterator<Map.Entry<K, V>> {EntrySpliterator(SimpleHashMap<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 SimpleHashMap.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();SimpleHashMap<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;} elsemc = 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.Entry<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;}}static class HashMapSpliterator<K, V> {final SimpleHashMap<K, V> map;Node<K, V> current;          // current nodeint index;                  // current index, modified on advance/splitint fence;                  // one past last indexint est;                    // size estimateint expectedModCount;       // for comodification checksHashMapSpliterator(SimpleHashMap<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 useint hi;if ((hi = fence) < 0) {SimpleHashMap<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 initreturn (long) est;}}final class EntrySet extends AbstractSet<Map.Entry<K, V>> {public final int size() {return size;}public final void clear() {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(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<>(SimpleHashMap.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 (Node<K, V> e : tab) {for (; e != null; e = e.next)action.accept(e);}if (modCount != mc)throw new ConcurrentModificationException();}}}abstract class HashIterator {Node<K, V> next;        // next entry to returnNode<K, V> current;     // current entryint expectedModCount;  // for fast-failint index;             // current slotHashIterator() {expectedModCount = modCount;Node<K, V>[] t = table;current = next = null;index = 0;if (t != null && size > 0) { // advance to first entrydo {} 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;removeNode(p.hash, p.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();}}/*** 红黑树** @param <K>* @param <V>*/static final class TreeNode<K, V> extends Entry<K, V> {TreeNode<K, V> parent;  // red-black tree linksTreeNode<K, V> left;TreeNode<K, V> right;TreeNode<K, V> prev;    // needed to unlink next upon deletionboolean red;TreeNode(int hash, K key, V val, Node<K, V> next) {super(hash, key, val, next);}/*** Returns root of tree containing this node.* 返回红黑树的root节点*/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.* 确认给定的root节点在table的首个节点中，即调整为头节点*/static <K, V> void moveRootToFront(Node<K, V>[] tab, TreeNode<K, V> root) {int n;if (root != null && tab != null && (n = tab.length) > 0) {//校验root是否为空、table是否为空、table的length是否大于0int index = (n - 1) & root.hash;//计算root节点的索引位置TreeNode<K, V> first = (TreeNode<K, V>) tab[index];//将root挪到头节点if (root != first) {//如果该索引位置的头节点不是root节点，则该索引位置的头节点替换为root节点Node<K, V> rn;tab[index] = root;//将该索引位置的头节点赋值为root节点TreeNode<K, V> rp = root.prev;//root节点的上一个节点if ((rn = root.next) != null)//如果root节点的next节点不为空，则将root节点的next节点的prev属性设置为root节点的prev节点((TreeNode<K, V>) rn).prev = rp;if (rp != null)//如果root节点的prev节点不为空，则将root节点的prev节点的next属性设置为root节点的next节点rp.next = rn;if (first != null)//如果原头节点不为空, 则将原头节点的prev属性设置为root节点first.prev = root;root.next = first;//将root节点的next属性设置为原头节点root.prev = null;//root此时已经被放到该位置的头节点位置，因此将prev属性设为空}assert checkInvariants(root);//该索引位置的头节点就是root节点,检查树是否正常}}/*** Finds the node starting at root p with the given hash and key.* The kc argument caches comparableClassFor(key) upon first use* comparing keys.* 1. 从调用此方法的节点开始查找, 通过hash值和key找到对应的节点* 2. 此方法是红黑树节点的查找, 红黑树是特殊的自平衡二叉查找树* 3. 平衡二叉查找树的特点： 左节点<根节点<右节点*/final TreeNode<K, V> find(int h, Object k, Class<?> kc) {TreeNode<K, V> p = this;//将p节点赋值为调用此方法的节点//从p节点开始向下遍历do {int ph, dir;K pk;TreeNode<K, V> pl = p.left, pr = p.right, q;if ((ph = p.hash) > h)//如果传入的hash值小于p节点的hash值，则往p节点的左边遍历p = pl;else if (ph < h)//如果传入的hash值和key值等于p节点的hash值和key值,则p节点为目标节点,返回p节点p = pr;else if ((pk = p.key) == k || (k != null && k.equals(pk)))//如果传入的hash值和key值等于p节点的hash值和key值,则p节点为目标节点,返回p节点return p;else if (pl == null)//p节点的左节点为空则将向右遍历p = pr;else if (pr == null)//p节点的右节点为空则向左遍历p = pl;else if ((kc != null ||//如果以上条件还不满足，则对p节点和k节点进行比较(kc = comparableClassFor(k)) != null) &&//kc不为空代表k实现了Comparable(dir = compareComparables(kc, k, pk)) != 0)//k<pk则dir<0, k>pk则dir>0p = (dir < 0) ? pl : pr;//根据dir进行判断向哪一边搜索else if ((q = pr.find(h, k, kc)) != null)//代码走到此处, 代表key所属类没有实现Comparable, 直接指定向p的右边遍历return q;elsep = pl;} while (p != null);return null;}/*** Calls find for root node.* 获取红黑树节点*/final TreeNode<K, V> getTreeNode(int h, Object k) {//1. 首先找到红黑树的根节点；//2. 再使用根节点调用find方法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.* 用于不可比较或者hashcode相同时进行比较的方法，只是一个一致的插入规则，用来维护重定位的等价性*/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.* 构建红黑树*/final void treeify(Node<K, V>[] tab) {TreeNode<K, V> root = null;// 将调用此方法的节点hd赋值给x，以x作为起点，开始进行遍历for (TreeNode<K, V> x = this, next; x != null; x = next) {// next赋值为x的下个节点next = (TreeNode<K, V>) x.next;// 将x的左右节点设置为空x.left = x.right = null;if (root == null) {// 如果还没有根节点, 则将x设置为根节点x.parent = null;// 根节点没有父节点x.red = false;// 根节点必须为黑色root = x;// 将x设置为根节点} else {//root不为空的时候K k = x.key;// k赋值为x的keyint h = x.hash;// h赋值为x的hash值Class<?> kc = null;// 当前节点x不是根节点, 则从根节点开始查找属于该节点的位置for (TreeNode<K, V> p = root; ; ) {int dir, ph;K pk = p.key;if ((ph = p.hash) > h)//如果x节点的hash值小于p节点的hash值，则将dir赋值为-1, 代表向p的左边查找dir = -1;else if (ph < h)//如果x节点的hash值大于p节点的hash值，则将dir赋值为1, 代表向p的右边查找dir = 1;else if ((kc == null &&(kc = comparableClassFor(k)) == null) ||(dir = compareComparables(kc, k, pk)) == 0)// 走到这代表x的hash值和p的hash值相等，则比较key值; 如果k没有实现Comparable接口 或者 x节点的key和p节点的key相等dir = tieBreakOrder(k, pk);//使用定义的一套规则来比较x节点和p节点的大小，用来决定向左还是向右查找TreeNode<K, V> xp = p;// xp赋值为x的父节点,中间变量用于下面给x的父节点赋值if ((p = (dir <= 0) ? p.left : p.right) == null) {//dir<=0则向p左边查找,否则向p右边查找,如果为null,则代表该位置即为x的目标位置//x和xp节点的属性设置x.parent = xp;//x的父节点即为最后一次遍历的p节点if (dir <= 0)// 如果时dir <= 0, 则代表x节点为父节点的左节点xp.left = x;else//如果时dir > 0, 则代表x节点为父节点的右节点xp.right = x;root = balanceInsertion(root, x);//进行红黑树的插入平衡(通过左旋、右旋和改变节点颜色来保证当前树符合红黑树的要求)break;}}}}moveRootToFront(tab, root);//如果root节点不在table索引位置的头节点, 则将其调整为头节点}/*** 重新创建节点，替换原有树结构的节点* @return 返回链表*/final Node<K, V> untreeify(SimpleHashMap<K, V> map) {//hd指向头节点, tl指向尾节点Node<K, V> hd = null, tl = null;for (Node<K, V> q = this; q != null; q = q.next) {//从调用该方法的节点, 即链表的头节点开始遍历, 将所有节点全转为链表节点Node<K, V> p = map.replacementNode(q, null);//创建节点nodeif (tl == null)//如果tl尾节点为null, 则代表当前节点为第一个节点, 将hd赋值为该节点hd = p;else//否则, 将尾节点的next属性设置为当前节点ptl.next = p;tl = p;//每次都将tl节点指向当前节点, 即尾节点}return hd;//返回转换后的链表的头节点}/*** Tree version of putVal.* 红黑树的put操作，红黑树插入会同时维护原来的链表属性, 即原来的next属性*/final TreeNode<K, V> putTreeVal(SimpleHashMap<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;//查找根节点, 索引位置的头节点并不一定为红黑树的根节点for (TreeNode<K, V> p = root; ; ) {//将根节点赋值给p节点，开始进行查找int dir, ph;K pk;if ((ph = p.hash) > h)//如果传入的hash值小于p节点的hash值，将dir赋值为-1，代表向p的左边查找树dir = -1;else if (ph < h)//如果传入的hash值大于p节点的hash值， 将dir赋值为1，代表向p的右边查找树dir = 1;else if ((pk = p.key) == k || (k != null && k.equals(pk)))//如果传入的hash值和key值等于p节点的hash值和key值, 则p节点即为目标节点, 返回p节点return p;else if ((kc == null &&(kc = comparableClassFor(k)) == null) ||(dir = compareComparables(kc, k, pk)) == 0) {//如果k所属的类没有实现Comparable接口 或者 k和p节点的key相等if (!searched) {//第一次符合条件, 从p节点的左节点和右节点分别调用find方法进行查找, 如果查找到目标节点则返回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))//否则使用定义的一套规则来比较k和p节点的key的大小, 用来决定向左还是向右查找return q;}dir = tieBreakOrder(k, pk);//dir<0则代表k<pk，则向p左边查找；反之亦然}TreeNode<K, V> xp = p;//xp赋值为x的父节点,中间变量,用于下面给x的父节点赋值if ((p = (dir <= 0) ? p.left : p.right) == null) {//dir<=0则向p左边查找,否则向p右边查找,如果为null,则代表该位置即为x的目标位置Node<K, V> xpn = xp.next;//走进来代表已经找到x的位置，只需将x放到该位置即可TreeNode<K, V> x = map.newTreeNode(h, k, v, xpn);//创建新的节点, 其中x的next节点为xpn, 即将x节点插入xp与xpn之间//调整x、xp、xpn之间的属性关系if (dir <= 0)//如果时dir <= 0, 则代表x节点为xp的左节点xp.left = x;else//如果时dir > 0, 则代表x节点为xp的右节点xp.right = x;xp.next = x;//将xp的next节点设置为xx.parent = x.prev = xp;if (xpn != null)//如果xpn不为空,则将xpn的prev节点设置为x节点,与上文的x节点的next节点对应((TreeNode<K, V>) xpn).prev = x;moveRootToFront(tab, balanceInsertion(root, x));//进行红黑树的插入平衡调整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(SimpleHashMap<K, V> map, Node<K, V>[] tab,boolean movable) {int n;if (tab == null || (n = tab.length) == 0)//table为空或者length为0直接返回return;int index = (n - 1) & hash;//根据hash计算出索引的位置TreeNode<K, V> first = (TreeNode<K, V>) tab[index], root = first, rl;//将索引位置的头节点赋值给first和rootTreeNode<K, V> succ = (TreeNode<K, V>) next, pred = prev;//该方法被将要被移除的node(TreeNode)调用, 因此此方法的this为要被移除node节点,将node的next节点赋值给succ节点，prev节点赋值给pred节点if (pred == null)//如果pred节点为空，则代表要被移除的node节点为头节点，则将table索引位置的值和first节点的值赋值为succ节点(node的next节点)即可tab[index] = first = succ;else//否则将pred节点的next属性设置为succ节点(node的next节点)pred.next = succ;if (succ != null)//如果succ节点不为空，则将succ的prev节点设置为pred, 与前面对应succ.prev = pred;if (first == null)//如果进行到此first节点为空，则代表该索引位置已经没有节点则直接返回return;if (root.parent != null)//如果root的父节点不为空, 则将root赋值为根节点root = root.root();if (root == null|| (movable&& (root.right == null|| (rl = root.left) == null|| rl.left == null))) {//通过root节点来判断此红黑树是否太小, 如果是则调用untreeify方法转为链表节点并返回，tab[index] = first.untreeify(map);  // too small, (转链表后就无需再进行下面的红黑树处理)return;}//红黑树的操作TreeNode<K, V> p = this, pl = left, pr = right, replacement;//将p赋值为要被移除的node节点，pl赋值为p的左节点，pr赋值为p 的右节点if (pl != null && pr != null) {//如果p的左节点和右节点都不为空时TreeNode<K, V> s = pr, sl;//将s节点赋值为p的右节点while ((sl = s.left) != null) // find successor 向左一直查找，跳出循环时,s为没有左节点的节点s = sl;boolean c = s.red;s.red = p.red;p.red = c; // swap colors 交换p节点和s节点的颜色TreeNode<K, V> sr = s.right;//s的右节点TreeNode<K, V> pp = p.parent;//p的父节点if (s == pr) { // 如果p节点的右节点即为s节点，则将p的父节点赋值为s，将s的右节点赋值为pp.parent = s;s.right = p;} else {TreeNode<K, V> sp = s.parent;//将sp赋值为s的父节点if ((p.parent = sp) != null) {//将p的父节点赋值为spif (s == sp.left)//如果s节点为sp的左节点，则将sp的左节点赋值为p节点sp.left = p;else//否则s节点为sp的右节点，则将sp的右节点赋值为p节点sp.right = p;//}if ((s.right = pr) != null)//s的右节点赋值为p节点的右节点pr.parent = s;//如果pr不为空，则将pr的父节点赋值为s}//第二次调整p.left = null;//将p的左节点赋值为空，pl已经保存了该节点if ((p.right = sr) != null)//将p节点的右节点赋值为sr，如果sr不为空，则将sr的父节点赋值为p节点sr.parent = p;if ((s.left = pl) != null)//将s节点的左节点赋值为pl，如果pl不为空，则将pl的父节点赋值为s节点pl.parent = s;if ((s.parent = pp) == null)//将s的父节点赋值为p的父节点pp，如果pp为空，则p节点为root节点, 交换后s成为新的root节点root = s;else if (p == pp.left)//如果p不为root节点, 并且p是pp的左节点，则将pp的左节点赋值为s节点pp.left = s;elsepp.right = s;if (sr != null)//寻找replacement节点，用来替换掉p节点; 如果sr不为空，则replacement节点为sr，因为s没有左节点，所以使用s的右节点来替换p的位置replacement = sr;else//如果sr为空，则s为叶子节点，replacement为p本身，只需要将p节点直接去除即可replacement = p;} else if (pl != null)//如果p的左节点不为空，右节点为空，replacement节点为p的左节点replacement = pl;else if (pr != null)//如果p的右节点不为空,左节点为空，replacement节点为p的右节点replacement = pr;else//如果p的左右节点都为空, 即p为叶子节点, replacement节点为p节点本身replacement = p;//第三次调整：使用replacement节点替换掉p节点的位置，将p节点移除if (replacement != p) {//如果p节点不是叶子节点TreeNode<K, V> pp = replacement.parent = p.parent;//将p节点的父节点赋值给replacement节点的父节点, 同时赋值给pp节点if (pp == null)//如果p没有父节点, 即p为root节点，则将root节点赋值为replacement节点即可(root = replacement).red = false;else if (p == pp.left)//如果p不是root节点, 并且p为pp的左节点，则将pp的左节点赋值为替换节点replacementpp.left = replacement;else//如果p不是root节点, 并且p为pp的右节点，则将pp的右节点赋值为替换节点replacementpp.right = replacement;p.left = p.right = p.parent = null;//p节点的位置已经被完整的替换为replacement, 将p节点清空, 以便垃圾收集器回收}//如果p节点不为红色则进行红黑树删除平衡调整,如果删除的节点是红色则不会破坏红黑树的平衡无需调整TreeNode<K, V> r = p.red ? root : balanceDeletion(root, replacement);if (replacement == p) {  // 如果p节点为叶子节点, 则简单的将p节点去除即可TreeNode<K, V> pp = p.parent;p.parent = null;//将p的parent属性设置为空if (pp != null) {if (p == pp.left)//如果p节点为父节点的左节点，则将父节点的左节点赋值为空pp.left = null;else if (p == pp.right)//如果p节点为父节点的右节点， 则将父节点的右节点赋值为空pp.right = null;}}if (movable)moveRootToFront(tab, r);//将root节点移到索引位置的头节点}/*** Splits nodes in a tree bin into lower and upper tree bins,* or untreeifies if now too small. Called only from resize;* see above discussion about split bits and indices.* 将树箱中的节点拆分为较低和较高的树箱，如果现在太小，则不进行校验。仅从resize调用；请参阅上文关于分割位和索引的讨论。* @param map 代表要扩容的HashMap* @param tab 代表新创建的数组，用来存放旧数组迁移的数据* @param index 代表旧数组的索引* @param bit 代表旧数组的长度，需要配合使用来做按位与运算*/final void split(SimpleHashMap<K, V> map, Node<K, V>[] tab, int index, int bit) {//做个赋值，因为这里是((TreeNode<K,V>)e)这个对象调用split()方法，// 所以this就是指(TreeNode<K,V>)e对象，所以才能类型对应赋值TreeNode<K, V> b = this;// Relink into lo and hi lists, preserving order// 设置低位首节点和低位尾节点TreeNode<K, V> loHead = null, loTail = null;//设置高位首节点和高位尾节点TreeNode<K, V> hiHead = null, hiTail = null;//定义两个变量，后边比较使用，它们决定了红黑树是否要转回链表int lc = 0, hc = 0;//这个for循环就是对从e节点开始对整个红黑树做遍历for (TreeNode<K, V> e = b, next; e != null; e = next) {//取e的下一节点赋值给next遍历next = (TreeNode<K, V>) e.next;//取好e的下一节点后，把它赋值为空，方便GC回收e.next = null;//如果e的hash值与老表的容量进行与运算为0,则扩容后的索引位置跟老表的索引位置一样/*e.hash与oldCap对应的有效高位上的值是0的话，哪怕扩容了，新数组索引还是不变，而如果e.hash与oldCap对应的有效高位上的值是1的话，那这个元素在新数组的下标位置就等于【原数组下标位置+原数组长度】。这样就通过这个运算把原来的一条链表拆成了两条链表，然后这两条链表各自归属到新数组中对应的位置。*/if ((e.hash & bit) == 0) {if ((e.prev = loTail) == null)loHead = e;elseloTail.next = e;loTail = e;//做个计数，看下拉出低位链表下会有几个元素++lc;} else {if ((e.prev = hiTail) == null)hiHead = e;elsehiTail.next = e;hiTail = e;//做个计数，看下拉出高位链表下会有几个元素++hc;}}if (loHead != null) {//如果低位链表首节点不为null，说明有这个链表存在if (lc <= UNTREEIFY_THRESHOLD)//当节点数量小于 红黑树结构转换为链表结构 的阀值，tab[index] = loHead.untreeify(map);//则将红黑树转为链表，低位链表，迁移到新数组中下标不变，还是等于原数组到下标else {//保持原有红黑树数据结构tab[index] = loHead;//低位链表，迁移到新数组中下标不变，还是等于原数组到下标，把低位链表整个拉到这个下标下，做个赋值if (hiHead != null) // //如果高位首节点不为空，说明原来的红黑树已经被拆分成两个链表了loHead.treeify(tab);//那么就需要构建新的红黑树了}}if (hiHead != null) {//如果高位链表首节点不为null，说明有这个链表存在if (hc <= UNTREEIFY_THRESHOLD)//当节点数量小于 红黑树结构转换为链表结构 的阀值，tab[index + bit] = hiHead.untreeify(map);//那就从红黑树转链表了，高位链表，迁移到新数组中的下标=【旧数组+旧数组长度】else {tab[index + bit] = hiHead;//高位链表，迁移到新数组中的下标=【旧数组+旧数组长度】，把高位链表整个拉到这个新下标下，做赋值if (loHead != null)//如果低位首节点不为空，说明原来的红黑树已经被拆分成两个链表了hiHead.treeify(tab);//那么就需要构建新的红黑树了}}}/* ------------------------------------------------------------ */// Red-black tree methods, all adapted from CLRstatic <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;elsepp.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;elsepp.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 { // symmetricif (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;}}
}