JDK8的HashMap数据结构上复杂了很多，因此读取效率得以大大提升，关于源码中红黑树的增删改查，博主没有细读，会在下一篇博文中使用Java实现红黑树的增删改查。
下面是类的结构图：
代码（摘抄自JDK）：
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.*;
/**
* hashMap
* 作为Kit ,保证健壮、高效，然后才是可阅读性
* http://www.mamicode.com/info-detail-2219646.html
* java红黑树：
* http://www.cnblogs.com/skywang12345/p/3624343.html
* hashMap中概念解读
* https://blog.csdn.net/fan2012huan/article/details/51087722
* hashmap解读：
* https://blog.csdn.net/AJ1101/article/details/79413939#commentBox
* <p>
* 概念摘抄：
* 约定前面的数组结构的每一个格格称为桶
* 约定桶后面存放的每一个数据称为bin
* bin这个术语来自于JDK 1.8的HashMap注释。
*
* @param <K>
* @param <V>
* @author jdk
*/
public class HappyMap<K, V> extends HashMap<K, V>
implements Map<K, V> {
/**
* The default initial capacity - MUST be a power of two.
*/
static final int DEFAULT_INITIAL_CAPACITY = 1 << 4;
/**
* The maximum capacity, used if a higher value is implicitly specified
* by either of the constructors with arguments.
* MUST be a power of two <= 1<<30.
* 最大容量，如果一个更高的值被构造函数用参数隐式指定，那么依旧使用这个容量
* <p>
* 必须是2的次方
*/
static final int MAXIMUM_CAPACITY = 1 << 30;
/**
* 当没有在构造函数里面指定，将使用这个默认负载因子
* The load factor used when none specified in constructor
*/
static final float DEFAULT_LOAD_FACTOR = 0.75f;
/**
* The bin count threshold for using a tree rather than list for a
* bin. Bins are converted to trees when adding an element to a
* bin with at least this many nodes. The value must be greater
* than 2 and should be at least 8 to mesh with assumptions in
* tree removal about conversion back to plain bins upon
* shrinkage.
* 一个bucket的树化阈值（红黑树）
* <p>
* 为bin使用tree还是list一个bin数目阈值。在至少达到这个数目节点的情况下增加元素，bins将会转化成tree。该值必须大于2，至少应该是8，与移除树的假设相适应。
*/
static final int TREEIFY_THRESHOLD = 8;
/**
* The bin count threshold for untreeifying a (split) bin during a
* resize operation. Should be less than TREEIFY_THRESHOLD, and at
* most 6 to mesh with shrinkage detection under removal.
* 一个树的链表还原阈值
* <p>
* 在调整大小操作时反树化（切分）一个bin的bin数目阈值，在移除时检测最大是6。
*/
static final int UNTREEIFY_THRESHOLD = 6;
/**
* The smallest table capacity for which bins may be treeified.
* (Otherwise the table is resized if too many nodes in a bin.)
* Should be at least 4 * TREEIFY_THRESHOLD to avoid conflicts
* between resizing and treeification thresholds.
* 树形化时bins的最小哈希表容量（否则如果bin中有太多的节点就对哈希表调整大小）。
* 为避免在调整大小和树形化阈值之间产生矛盾，这个值至少是4 * TREEIFY_THERSHOLD。
*/
static final int MIN_TREEIFY_CAPACITY = 64;
/**
* NODE-use HashMap
* Basic hash bin node, used for most entries. (See below for
* TreeNode subclass, and in LinkedHashMap for its Entry subclass.)
*/
static class Node<K, V> implements Map.Entry<K, V> {
final int hash;
final K key;
V value;
HappyMap.Node<K, V> next;
Node(int hash, K key, V value, HappyMap.Node<K, V> next) {
this.hash = hash;
this.key = key;
this.value = value;
this.next = next;
}
@Override
public final K getKey() {
return key;
}
@Override
public final V getValue() {
return value;
}
@Override
public final String toString() {
return key + "=" + value;
}
@Override
public final int hashCode() {
return Objects.hashCode(key) ^ Objects.hashCode(value);
}
@Override
public final V setValue(V newValue) {
V oldValue = value;
value = newValue;
return oldValue;
}
@Override
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;
}
}
/**
* Create a tree bin node
*/
HappyMap.TreeNode<K, V> newTreeNode(int hash, K key, V value, HappyMap.Node<K, V> next) {
return new HappyMap.TreeNode<>(hash, key, value, next);
}
/* ---------------- Static utilities(没抄) -------------- */
/* ---------------- Fields -------------- */
/**
* The table, initialized on first use, and resized as
* necessary. When allocated, length is always a power of two.
* (We also tolerate length zero in some operations to allow
* bootstrapping mechanics that are currently not needed.)
*/
transient HappyMap.Node<K, V>[] table;
/**
* Holds cached entrySet(). Note that AbstractMap fields are used
* for keySet() and values().
*/
transient Set<Map.Entry<K, V>> entrySet;
/**
* The number of key-value mappings contained in this map.
*/
transient int size;
/**
* The number of times this HashMap has been structurally modified
* Structural modifications are those that change the number of mappings in
* the HashMap or otherwise modify its internal structure (e.g.,
* rehash). This field is used to make iterators on Collection-views of
* the HashMap fail-fast. (See ConcurrentModificationException).
*/
transient int modCount;
/**
* The next size value at which to resize (capacity * load factor).
* threshold表示当HashMap的size大于threshold时会执行resize操作。
* threshold=capacity*loadFactor
*
* @serial
*/
// (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;
/**
* The load factor for the hash table.
*
* @serial
*/
final float loadFactor;
/**
* Constructs an empty <tt>HashMap</tt> with the default initial capacity
* (16) and the default load factor (0.75).
*/
public HappyMap() {
// all other fields defaulted
this.loadFactor = DEFAULT_LOAD_FACTOR;
}
/* ---------------- Public operations -------------- */
@Override
public Set<Entry<K, V>> entrySet() {
return null;
}
/**
* Returns the number of key-value mappings in this map.
*
* @return the number of key-value mappings in this map
*/
@Override
public int size() {
return size;
}
/**
* Returns <tt>true</tt> if this map contains no key-value mappings.
*
* @return <tt>true</tt> if this map contains no key-value mappings
*/
@Override
public boolean isEmpty() {
return size == 0;
}
/**
* Computes key.hashCode() and spreads (XORs) higher bits of hash
* to lower. Because the table uses power-of-two masking, sets of
* hashes that vary only in bits above the current mask will
* always collide. (Among known examples are sets of Float keys
* holding consecutive whole numbers in small tables.) So we
* apply a transform that spreads the impact of higher bits
* downward. There is a tradeoff between speed, utility, and
* quality of bit-spreading. Because many common sets of hashes
* are already reasonably distributed (so don't benefit from
* spreading), and because we use trees to handle large sets of
* collisions in bins, we just XOR some shifted bits in the
* cheapest possible way to reduce systematic lossage, as well as
* to incorporate impact of the highest bits that would otherwise
* never be used in index calculations because of table bounds.
*/
static final int hash(Object key) {
int h;
return (key == null) ? 0 : (h = key.hashCode()) ^ (h >>> 16);
}
/**
* Associates the specified value with the specified key in this map.
* If the map previously contained a mapping for the key, the old
* value is replaced.
*
* @param key key with which the specified value is to be associated
* @param value value to be associated with the specified key
* @return the previous value associated with <tt>key</tt>, or
* <tt>null</tt> if there was no mapping for <tt>key</tt>.
* (A <tt>null</tt> return can also indicate that the map
* previously associated <tt>null</tt> with <tt>key</tt>.)
*/
@Override
public V put(K key, V value) {
return putVal(hash(key), key, value, false, true);
}
/**
* Implements Map.put and related methods
*
* @param hash hash for key
* @param key the key
* @param value the value to put
* @param onlyIfAbsent if true, don't change existing value
* @param evict if false, the table is in creation mode.
* @return previous value, or null if none
*/
final V putVal(int hash, K key, V value, boolean onlyIfAbsent,
boolean evict) {
HappyMap.Node<K, V>[] tab;
HappyMap.Node<K, V> calPosiNode;
int tabLenth, position;
//如果 table属性 为空，初始化定义大小,返回新的长度（初始化长度）
if ((tab = table) == null || (tabLenth = tab.length) == 0) {
tabLenth = (tab = resize()).length;
}
//hash(key)&(n-1)查找位置，如果位置上的Node为null，新建一个Node
if ((calPosiNode = tab[position = (tabLenth - 1) & hash]) == null) {
tab[position] = newNode(hash, key, value, null);
} else {//如果位置上有Node了
HappyMap.Node<K, V> tempNode;
K k;
//新旧元素key值相等（或哈希值相同，地址相等），覆盖
if (calPosiNode.hash == hash && ((k = calPosiNode.key) == key || (key != null && key.equals(k)))) {
tempNode = calPosiNode;
//如果key不相等且是此位置上的RB树节点
} else if (calPosiNode instanceof HappyMap.TreeNode) {
tempNode = ((HappyMap.TreeNode<K, V>) calPosiNode).putTreeVal(this, tab, hash, key, value);
} else {//key 不相等 且非RB树节点
for (int binCount = 0; ; ++binCount) {
// 当链表只有一个头部结点，则新建（append）一个结点
if ((tempNode = calPosiNode.next) == null) {
calPosiNode.next = newNode(hash, key, value, null);
// 链表长度大于8（0 to 7）时，将链表转红黑树
if (binCount >= TREEIFY_THRESHOLD - 1) {
treeifyBin(tab, hash);
}
break;
}
if (tempNode.hash == hash && ((k = tempNode.key) == key || (key != null && key.equals(k)))) {
break;
}
//更新
calPosiNode = tempNode;
}
}
// existing mapping for key
if (tempNode != null) {
V oldValue = tempNode.value;
if (!onlyIfAbsent || oldValue == null) {
tempNode.value = value;
}
afterNodeAccess(tempNode);
return oldValue;
}
}
++modCount;
if (++size > threshold) {
resize();
}
afterNodeInsertion(evict);
return null;
}
// Callbacks to allow LinkedHashMap post-actions
void afterNodeAccess(HappyMap.Node<K, V> p) {
}
void afterNodeInsertion(boolean evict) {
}
/**
* Initializes or doubles table size. If null, allocates in
* accord with initial capacity target held in field threshold.
* Otherwise, because we are using power-of-two expansion, the
* elements from each bin must either stay at same index, or move
* with a power of two offset in the new table.
* 初始化或者扩容之后元素调整
*
* @return the table
*/
final HappyMap.Node<K, V>[] resize() {
HappyMap.Node<K, V>[] oldTab = table;
//原数组长度
int oldCap = (oldTab == null) ? 0 : oldTab.length;
//原扩充临界值
int oldThr = threshold;
int newCap, newThr = 0;
//table不为空
if (oldCap > 0) {
//如果数组长度达到最大值，则修改临界值为Integer.MAX_VALUE
if (oldCap >= MAXIMUM_CAPACITY) {
threshold = Integer.MAX_VALUE;
return oldTab;
}
//没有达到最大值则容量*2
else if ((newCap = oldCap << 1) < MAXIMUM_CAPACITY &&
oldCap >= DEFAULT_INITIAL_CAPACITY) {
// doubles threshold
newThr = oldThr << 1;
}
}
// initial capacity was placed in threshold(直接赋值)
else if (oldThr > 0) {
newCap = oldThr;
}
// zero initial threshold signifies using defaults（初始化容量与边界）
else {
newCap = DEFAULT_INITIAL_CAPACITY;
newThr = (int) (DEFAULT_LOAD_FACTOR * DEFAULT_INITIAL_CAPACITY);
}
if (newThr == 0) {
float ft = (float) newCap * loadFactor;
newThr = (newCap < MAXIMUM_CAPACITY && ft < (float) MAXIMUM_CAPACITY ?
(int) ft : Integer.MAX_VALUE);
}
threshold = newThr;
@SuppressWarnings({"rawtypes", "unchecked"})
HappyMap.Node<K, V>[] newTab = (HappyMap.Node<K, V>[]) new HappyMap.Node[newCap];
table = newTab;
// 调整数组大小之后，需要调整红黑树或者链表的指向
if (oldTab != null) {
for (int j = 0; j < oldCap; ++j) {
HappyMap.Node<K, V> e;
if ((e = oldTab[j]) != null) {
oldTab[j] = null;
if (e.next == null) {
newTab[e.hash & (newCap - 1)] = e;
}
// 红黑树调整
else if (e instanceof HappyMap.TreeNode) {
((HappyMap.TreeNode<K, V>) e).split(this, newTab, j, oldCap);
}
// preserve order链表顺序调整
else {
HappyMap.Node<K, V> loHead = null, loTail = null;
HappyMap.Node<K, V> hiHead = null, hiTail = null;
HappyMap.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);
if (loTail != null) {
loTail.next = null;
newTab[j] = loHead;
}
if (hiTail != null) {
hiTail.next = null;
newTab[j + oldCap] = hiHead;
}
}
}
}
}
return newTab;
}
// Create a regular (non-tree) node
HappyMap.Node<K, V> newNode(int hash, K key, V value, HappyMap.Node<K, V> next) {
return new HappyMap.Node<>(hash, key, value, next);
}
// For conversion from TreeNodes to plain nodes
HappyMap.Node<K, V> replacementNode(HappyMap.Node<K, V> p, HappyMap.Node<K, V> next) {
return new HappyMap.Node<>(p.hash, p.key, p.value, next);
}
/**
* Replaces all linked nodes in bin at index for given hash unless
* table is too small, in which case resizes instead.
* bin（Node）转换为 TreeNode
*/
final void treeifyBin(HappyMap.Node<K, V>[] tab, int hash) {
int n, index;
HappyMap.Node<K, V> e;
if (tab == null || (n = tab.length) < MIN_TREEIFY_CAPACITY) {
resize();
} else if ((e = tab[index = (n - 1) & hash]) != null) {
HappyMap.TreeNode<K, V> hd = null, tl = null;
do {
//Node转TreeNode
HappyMap.TreeNode<K, V> p = replacementTreeNode(e, null);
if (tl == null) {
hd = p;
} else {
p.prev = tl;
tl.next = p;
}
tl = p;
} while ((e = e.next) != null);
if ((tab[index] = hd) != null) {
//转为红黑树
hd.treeify(tab);
}
}
}
// For treeifyBin
HappyMap.TreeNode<K, V> replacementTreeNode(HappyMap.Node<K, V> p, HappyMap.Node<K, V> next) {
return new HappyMap.TreeNode<>(p.hash, p.key, p.value, next);
}
/**
* HashMap.Node subclass for normal LinkedHashMap entries.
*/
/* ------------------------------------------------------------ */
/**
* Returns x's Class if it is of the form "class C implements
* Comparable<C>", else null.
*/
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;
}
/**
* Returns k.compareTo(x) if x matches kc (k's screened comparable
* class), else 0.
*/
@SuppressWarnings({"rawtypes", "unchecked"}) // for cast to Comparable
static int compareComparables(Class<?> kc, Object k, Object x) {
return (x == null || x.getClass() != kc ? 0 :
((Comparable) k).compareTo(x));
}
/**
* Returns the value to which the specified key is mapped,
* or {@code null} if this map contains no mapping for the key.
*
* <p>More formally, if this map contains a mapping from a key
* {@code k} to a value {@code v} such that {@code (key==null ? k==null :
* key.equals(k))}, then this method returns {@code v}; otherwise
* it returns {@code null}. (There can be at most one such mapping.)
*
* <p>A return value of {@code null} does not <i>necessarily</i>
* indicate that the map contains no mapping for the key; it's also
* possible that the map explicitly maps the key to {@code null}.
* The {@link #containsKey containsKey} operation may be used to
* distinguish these two cases.
*
* @see #put(Object, Object)
*/
@Override
public V get(Object key) {
HappyMap.Node<K, V> e;
return (e = getNode(hash(key), key)) == null ? null : e.value;
}
/**
* Implements Map.get and related methods
*
* @param hash hash for key
* @param key the key
* @return the node, or null if none
*/
final HappyMap.Node<K, V> getNode(int hash, Object key) {
HappyMap.Node<K, V>[] tab;
HappyMap.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 && // always check first node
((k = first.key) == key || (key != null && key.equals(k))))
return first;
if ((e = first.next) != null) {
if (first instanceof HappyMap.TreeNode)
return ((HappyMap.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;
}
// Tree bins
/**
* Entry for Tree bins. Extends LinkedHashMap.Entry (which in turn
* extends Node) so can be used as extension of either regular or
* linked node.
*/
static final class TreeNode<K, V> extends HappyMap.Node<K, V> {
HappyMap.Entry<K, V> before, after;
// TreeNode(int hash, K key, V value, HappyMap.Node<K,V> next) {
// super(hash, key, value, next);
// }
HappyMap.TreeNode<K, V> parent; // red-black tree links
HappyMap.TreeNode<K, V> left;
HappyMap.TreeNode<K, V> right;
HappyMap.TreeNode<K, V> prev; // needed to unlink next upon deletion
boolean red;
TreeNode(int hash, K key, V val, HappyMap.Node<K, V> next) {
super(hash, key, val, next);
}
/**
* Returns root of tree containing this node.
*/
final HappyMap.TreeNode<K, V> root() {
for (HappyMap.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(HappyMap.Node<K, V>[] tab, HappyMap.TreeNode<K, V> root) {
int n;
if (root != null && tab != null && (n = tab.length) > 0) {
int index = (n - 1) & root.hash;
HappyMap.TreeNode<K, V> first = (HappyMap.TreeNode<K, V>) tab[index];
if (root != first) {
HappyMap.Node<K, V> rn;
tab[index] = root;
HappyMap.TreeNode<K, V> rp = root.prev;
if ((rn = root.next) != null)
((HappyMap.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 HappyMap.TreeNode<K, V> find(int h, Object k, Class<?> kc) {
HappyMap.TreeNode<K, V> p = this;
do {
int ph, dir;
K pk;
HappyMap.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 HappyMap.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.
* 将链表中每个值进行红黑树插入操作
*
* @return root of tree
*/
final void treeify(HappyMap.Node<K, V>[] tab) {
HappyMap.TreeNode<K, V> root = null;
for (HappyMap.TreeNode<K, V> x = this, next; x != null; x = next) {
next = (HappyMap.TreeNode<K, V>) x.next;
// 初始化Root
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;
//TREENODE节点插入
for (HappyMap.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);
}
HappyMap.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 HappyMap.Node<K, V> untreeify(HappyMap<K, V> map) {
HappyMap.Node<K, V> hd = null, tl = null;
for (HappyMap.Node<K, V> q = this; q != null; q = q.next) {
HappyMap.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.
* 红黑树节点插入
*/
final HappyMap.TreeNode<K, V> putTreeVal(HappyMap<K, V> map,
HappyMap.Node<K, V>[] tab,
int h,
K k,
V v) {
Class<?> kc = null;
boolean searched = false;
HappyMap.TreeNode<K, V> root = (parent != null) ? root() : this;
for (HappyMap.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) {
HappyMap.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);
}
HappyMap.TreeNode<K, V> xp = p;
if ((p = (dir <= 0) ? p.left : p.right) == null) {
HappyMap.Node<K, V> xpn = xp.next;
HappyMap.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)
((HappyMap.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(HappyMap<K, V> map, HappyMap.Node<K, V>[] tab,
boolean movable) {
int n;
if (tab == null || (n = tab.length) == 0)
return;
int index = (n - 1) & hash;
HappyMap.TreeNode<K, V> first = (HappyMap.TreeNode<K, V>) tab[index], root = first, rl;
HappyMap.TreeNode<K, V> succ = (HappyMap.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;
}
HappyMap.TreeNode<K, V> p = this, pl = left, pr = right, replacement;
if (pl != null && pr != null) {
HappyMap.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
HappyMap.TreeNode<K, V> sr = s.right;
HappyMap.TreeNode<K, V> pp = p.parent;
if (s == pr) { // p was s's direct parent
p.parent = s;
s.right = p;
} else {
HappyMap.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) {
HappyMap.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;
}
HappyMap.TreeNode<K, V> r = p.red ? root : balanceDeletion(root, replacement);
if (replacement == p) { // detach
HappyMap.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);
}
/**
* 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.
*
* @param map the map
* @param tab the table for recording bin heads
* @param index the index of the table being split
* @param bit the bit of hash to split on
*/
final void split(HappyMap<K, V> map, HappyMap.Node<K, V>[] tab, int index, int bit) {
HappyMap.TreeNode<K, V> b = this;
// Relink into lo and hi lists, preserving order
HappyMap.TreeNode<K, V> loHead = null, loTail = null;
HappyMap.TreeNode<K, V> hiHead = null, hiTail = null;
int lc = 0, hc = 0;
for (HappyMap.TreeNode<K, V> e = b, next; e != null; e = next) {
next = (HappyMap.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> HappyMap.TreeNode<K, V> rotateLeft(HappyMap.TreeNode<K, V> root,
HappyMap.TreeNode<K, V> p) {
HappyMap.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> HappyMap.TreeNode<K, V> rotateRight(HappyMap.TreeNode<K, V> root,
HappyMap.TreeNode<K, V> p) {
HappyMap.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;
}
/**
* 插入后的平衡操作
*
* @param root
* @param x
* @param <K>
* @param <V>
* @return
*/
static <K, V> HappyMap.TreeNode<K, V> balanceInsertion(HappyMap.TreeNode<K, V> root,
HappyMap.TreeNode<K, V> x) {
x.red = true;
for (HappyMap.TreeNode<K, V> xp, xpp, xppl, xppr; ; ) {
//空
if ((xp = x.parent) == null) {
x.red = false;
return x;
}
//root
else if (!xp.red || (xpp = xp.parent) == null) {
return root;
}
//左子树插入
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 {
//右子树插入
// 祖父结点不为空，并且颜色为红色时
if (xppl != null && xppl.red) {
xppl.red = false;
xp.red = false;
xpp.red = true;
x = xpp;
} else {
// 左子树插入
if (x == xp.left) {
root = rotateRight(root, x = xp);
xpp = (xp = x.parent) == null ? null : xp.parent;
}
// x 的父亲结点设置成黑色
if (xp != null) {
xp.red = false;
if (xpp != null) {
xpp.red = true;
// 左旋
root = rotateLeft(root, xpp);
}
}
}
}
}
}
static <K, V> HappyMap.TreeNode<K, V> balanceDeletion(HappyMap.TreeNode<K, V> root,
HappyMap.TreeNode<K, V> x) {
for (HappyMap.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 {
HappyMap.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 {
HappyMap.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(HappyMap.TreeNode<K, V> t) {
HappyMap.TreeNode<K, V> tp = t.parent, tl = t.left, tr = t.right,
tb = t.prev, tn = (HappyMap.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;
}
}
}