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| public V put(K key, V value) {
Entry<K,V> t = root;
if (t == null) { //根节点为空
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) { //比较器，使用定制的排序方法
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); //Key 存在，更新value
} while (t != null);
}
else { //比较器为null，Key 必须实现 Comparable 接口
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); //Key 存在，更新value
} while (t != null);
}
//Key 不存在，新建节点，插入二叉树
Entry<K,V> e = new Entry<>(key, value, parent);
if (cmp < 0)
parent.left = e;
else
parent.right = e;
//插入后修复红黑树
fixAfterInsertion(e);
size++;//数量增加
modCount++;//结构改变
return null;
} |
