IDEA激活码
一、属性
1.1 Entry
static final class Entry<K,V> implements Map.Entry<K,V> {
K key;
V value;
Entry<K,V> left;
Entry<K,V> right;
Entry<K,V> parent;
boolean color = BLACK;
/**
* Make a new cell with given key, value, and parent, and with
* {@code null} child links, and BLACK color.
*/
Entry(K key, V value, Entry<K,V> parent) {
this.key = key;
this.value = value;
this.parent = parent;
}
/**
* Returns the key.
*
* @return the key
*/
public K getKey() {
return key;
}
/**
* Returns the value associated with the key.
*
* @return the value associated with the key
*/
public V getValue() {
return value;
}
/**
* Replaces the value currently associated with the key with the given
* value.
*
* @return the value associated with the key before this method was
* called
*/
public V setValue(V value) {
V oldValue = this.value;
this.value = value;
return oldValue;
}
public boolean equals(Object o) {
if (!(o instanceof Map.Entry))
return false;
Map.Entry<?,?> e = (Map.Entry<?,?>)o;
return valEquals(key,e.getKey()) && valEquals(value,e.getValue());
}
public int hashCode() {
int keyHash = (key==null ? 0 : key.hashCode());
int valueHash = (value==null ? 0 : value.hashCode());
return keyHash ^ valueHash;
}
public String toString() {
return key + "=" + value;
}
}
二、方法
2.1 put
将特定的键值对储存进入map中，如果这个map已经包含了Key，那么更新Value的值，同时会返回这个旧值。如果不包含这个Key，那么返回null，注意返回null还有可能是Key对应的值为null。
/**
* @throws ClassCastException if the specified key cannot be compared
* with the keys currently in the map
* @throws NullPointerException if the specified key is null
* and this map uses natural ordering, or its comparator
* does not permit null keys
*/
public V put(K key, V value) {
Entry<K,V> t = root;
if (t == null) {
compare(key, key); // type (and possibly null) check
root = new Entry<>(key, value, null);
size = 1;
modCount++;
return null;
}
int cmp;
Entry<K,V> parent;
// split comparator and comparable paths
Comparator<? super K> cpr = comparator;
if (cpr != null) {
do {
parent = t;
cmp = cpr.compare(key, t.key);
if (cmp < 0)
t = t.left;
else if (cmp > 0)
t = t.right;
else
return t.setValue(value);
} while (t != null);
}
else {
if (key == null)
throw new NullPointerException();
@SuppressWarnings("unchecked")
Comparable<? super K> k = (Comparable<? super K>) key;
do {
parent = t;
cmp = k.compareTo(t.key);
if (cmp < 0)
t = t.left;
else if (cmp > 0)
t = t.right;
else
return t.setValue(value);
} while (t != null);
}
Entry<K,V> e = new Entry<>(key, value, parent);
if (cmp < 0)
parent.left = e;
else
parent.right = e;
fixAfterInsertion(e);
size++;
modCount++;
return null;
}
2.2 get
返回和特定Key值对应的Value，如果不存在，返回null（注意返回null还有可能是Key对应的Value等于null，可以用containsKey来进行区分）。
/**
* @throws ClassCastException if the specified key cannot be compared
* with the keys currently in the map
* @throws NullPointerException if the specified key is null
* and this map uses natural ordering, or its comparator
* does not permit null keys
*/
public V get(Object key) {
Entry<K,V> p = getEntry(key);
return (p==null ? null : p.value);
}
2.2.1 getEntry
返回和Key相对应的map的实体，如果不存在，返回null。
/**
* @throws ClassCastException if the specified key cannot be compared
* with the keys currently in the map
* @throws NullPointerException if the specified key is null
* and this map uses natural ordering, or its comparator
* does not permit null keys
*/
final Entry<K,V> getEntry(Object key) {
// Offload comparator-based version for sake of performance
if (comparator != null)
return getEntryUsingComparator(key);
if (key == null)
throw new NullPointerException();
@SuppressWarnings("unchecked")
Comparable<? super K> k = (Comparable<? super K>) key;
Entry<K,V> p = root;
while (p != null) {
int cmp = k.compareTo(p.key);
if (cmp < 0)
p = p.left;
else if (cmp > 0)
p = p.right;
else
return p;
}
return null;
}
2.2.1.1 getEntryUsingComparator
使用Comparator进行判断的版本
/**
* Version of getEntry using comparator. Split off from getEntry
* for performance. (This is not worth doing for most methods,
* that are less dependent on comparator performance, but is
* worthwhile here.)
*/
final Entry<K,V> getEntryUsingComparator(Object key) {
@SuppressWarnings("unchecked")
K k = (K) key;
Comparator<? super K> cpr = comparator;
if (cpr != null) {
Entry<K,V> p = root;
while (p != null) {
int cmp = cpr.compare(k, p.key);
if (cmp < 0)
p = p.left;
else if (cmp > 0)
p = p.right;
else
return p;
}
}
return null;
}
2.3 containsValue
如果有至少一个的Key对应这个Value值，则返回true，这个操作是线性的时间复杂度（意味着要遍历整个树）
public boolean containsValue(Object value) {
for (Entry<K,V> e = getFirstEntry(); e != null; e = successor(e))
if (valEquals(value, e.value))
return true;
return false;
}
2.4 getFirstEntry
返回二叉搜索树的最小节点
final Entry<K,V> getFirstEntry() {
Entry<K,V> p = root;
if (p != null)
while (p.left != null)
p = p.left;
return p;
}
2.5 getLastEntry
返回二叉搜索树的最大节点
final Entry<K,V> getLastEntry() {
Entry<K,V> p = root;
if (p != null)
while (p.right != null)
p = p.right;
return p;
}
2.6 remove
如果存在和Key对应的键值对，那么在这个TreeMap中删除这个键值对。返回之前和这个Key对应的Value，如果不存在，返回null（注意返回null也可能是Key对应的Value值为null）
/*
* @throws ClassCastException if the specified key cannot be compared
* with the keys currently in the map
* @throws NullPointerException if the specified key is null
* and this map uses natural ordering, or its comparator
* does not permit null keys
*/
public V remove(Object key) {
Entry<K,V> p = getEntry(key);
if (p == null)
return null;
V oldValue = p.value;
deleteEntry(p);
return oldValue;
}
2.6.1 deleteEntry
private void deleteEntry(Entry<K,V> p) {
modCount++;
size--;
// If strictly internal, copy successor's element to p and then make p
// point to successor.
if (p.left != null && p.right != null) {
//这里s是p右孩子中最小的节点
Entry<K,V> s = successor(p);
p.key = s.key;
p.value = s.value;
p = s;
} // p has 2 children
// Start fixup at replacement node, if it exists.
Entry<K,V> replacement = (p.left != null ? p.left : p.right);
//p只有一个孩子的情况
if (replacement != null) {
// Link replacement to parent
replacement.parent = p.parent;
if (p.parent == null)
root = replacement;
else if (p == p.parent.left)
p.parent.left = replacement;
else
p.parent.right = replacement;
//这里做的操作是先删除p，然后调整树
// Null out links so they are OK to use by fixAfterDeletion.
p.left = p.right = p.parent = null;
// Fix replacement
if (p.color == BLACK)
fixAfterDeletion(replacement);
} else if (p.parent == null) { // return if we are the only node.
root = null;
} else {
//p是叶子节点的情况
//先调整，再删除
if (p.color == BLACK)
fixAfterDeletion(p);
if (p.parent != null) {
if (p == p.parent.left)
p.parent.left = null;
else if (p == p.parent.right)
p.parent.right = null;
p.parent = null;
}
}
}
2.7 successor
寻找传入节点的后继节点
/**
* Returns the successor of the specified Entry, or null if no such.
*/
static <K,V> TreeMap.Entry<K,V> successor(Entry<K,V> t) {
if (t == null)
return null;
else if (t.right != null) {
Entry<K,V> p = t.right;
while (p.left != null)
p = p.left;
return p;
} else {
Entry<K,V> p = t.parent;
Entry<K,V> ch = t;
while (p != null && ch == p.right) {
ch = p;
p = p.parent;
}
return p;
}
}
2.8 predecessor
寻找当前节点的前驱节点
/**
* Returns the predecessor of the specified Entry, or null if no such.
*/
static <K,V> Entry<K,V> predecessor(Entry<K,V> t) {
if (t == null)
return null;
else if (t.left != null) {
Entry<K,V> p = t.left;
while (p.right != null)
p = p.right;
return p;
} else {
Entry<K,V> p = t.parent;
Entry<K,V> ch = t;
while (p != null && ch == p.left) {
ch = p;
p = p.parent;
}
return p;
}
}
2.9 fixAfterInsertion
/** From CLR */
private void fixAfterInsertion(Entry<K,V> x) {
x.color = RED;
while (x != null && x != root && x.parent.color == RED) {
//父节点是爷爷结点的左结点
if (parentOf(x) == leftOf(parentOf(parentOf(x)))) {
//取得父亲结点的兄弟结点（叔叔结点）
Entry<K,V> y = rightOf(parentOf(parentOf(x)));
//叔叔结点为红色，此时子节点可左可右
if (colorOf(y) == RED) {
//将父亲结点和叔叔结点染黑
setColor(parentOf(x), BLACK);
setColor(y, BLACK);
//将爷爷结点染红
setColor(parentOf(parentOf(x)), RED);
//X回溯至爷爷结点
x = parentOf(parentOf(x));
} else {//叔叔结点为黑色
if (x == rightOf(parentOf(x))) {//X是P的右孩子
//x指向p
x = parentOf(x);
//左旋p
rotateLeft(x);
}
//将P染黑，G染红
setColor(parentOf(x), BLACK);
setColor(parentOf(parentOf(x)), RED);
//右旋G
rotateRight(parentOf(parentOf(x)));
}
} else {
Entry<K,V> y = leftOf(parentOf(parentOf(x)));
if (colorOf(y) == RED) {
setColor(parentOf(x), BLACK);
setColor(y, BLACK);
setColor(parentOf(parentOf(x)), RED);
x = parentOf(parentOf(x));
} else {
if (x == leftOf(parentOf(x))) {
x = parentOf(x);
rotateRight(x);
}
setColor(parentOf(x), BLACK);
setColor(parentOf(parentOf(x)), RED);
rotateLeft(parentOf(parentOf(x)));
}
}
}
root.color = BLACK;
}
2.10 fixAfterDeletion
/** From CLR */
private void fixAfterDeletion(Entry<K,V> x) {
//节点x的颜色为黑
while (x != root && colorOf(x) == BLACK) {
//当x是左节点时
if (x == leftOf(parentOf(x))) {
Entry<K,V> sib = rightOf(parentOf(x));
//第一种情况，兄弟节点S为红色
if (colorOf(sib) == RED) {
//将S染黑
setColor(sib, BLACK);
//将P染红，左旋P
setColor(parentOf(x), RED);
rotateLeft(parentOf(x));
sib = rightOf(parentOf(x));
}
//兄弟节点为黑色的情况
if (colorOf(leftOf(sib)) == BLACK &&
colorOf(rightOf(sib)) == BLACK) {
//左侄子和右侄子均为黑色
//将S染红
setColor(sib, RED);
//X回溯至P
x = parentOf(x);
} else {
if (colorOf(rightOf(sib)) == BLACK) {//S为黑色，LN为红色，RN为黑色
//将LN染黑
setColor(leftOf(sib), BLACK);
//将S染红
setColor(sib, RED);
//右旋S
rotateRight(sib);
//S指向LN
sib = rightOf(parentOf(x));
}
//第四种情况
//S为黑色，P可红可黑，RN为红色，LN可红可黑
//将S的颜色设置为与P相同
setColor(sib, colorOf(parentOf(x)));
//P染黑
setColor(parentOf(x), BLACK);
//RN染黑
setColor(rightOf(sib), BLACK);
//左旋P
rotateLeft(parentOf(x));
//X回溯至根节点
x = root;
}
} else { // symmetric
Entry<K,V> sib = leftOf(parentOf(x));
if (colorOf(sib) == RED) {
setColor(sib, BLACK);
setColor(parentOf(x), RED);
rotateRight(parentOf(x));
sib = leftOf(parentOf(x));
}
if (colorOf(rightOf(sib)) == BLACK &&
colorOf(leftOf(sib)) == BLACK) {
setColor(sib, RED);
x = parentOf(x);
} else {
if (colorOf(leftOf(sib)) == BLACK) {
setColor(rightOf(sib), BLACK);
setColor(sib, RED);
rotateLeft(sib);
sib = leftOf(parentOf(x));
}
setColor(sib, colorOf(parentOf(x)));
setColor(parentOf(x), BLACK);
setColor(leftOf(sib), BLACK);
rotateRight(parentOf(x));
x = root;
}
}
}
//回溯过程，不管X是根节点还是红色节点，均调整为黑色
setColor(x, BLACK);
}
