putTreeMap.java

	public V put(K key, V value) {
		Entry<K, V> entry = this.root;
		if (entry == null) {
			this.root = new Entry<>(key, value, null);
			return null;
		}
		int cmp;
		Entry<K, V> parent;
		Comparator<? super K> cpr = comparator;
		if (cpr != null) {
			do {
				parent = entry;
				cmp = cpr.compare(key, entry.key);
				if (cmp < 0) {
					entry = entry.left;
				} else if (cmp > 0) {
					entry = entry.right;
				} else {
					return entry.setValue(value);
				}
			} while (entry != null);
		} else {
			if (key == null) throw new NullPointerException();
			Comparable<? super K> keyOfInsertValue = (Comparable<? super K>) key;
			do {
				parent = entry;
				cmp = keyOfInsertValue.compareTo(entry.key);
				if (cmp < 0) {
					entry = entry.left;
				} else if (cmp > 0) {
					entry = entry.right;
				} else {
					return entry.setValue(value);
				}
			} while (entry != null);
		}
		Entry<K, V> entryOfKey = new Entry<>(key, value, parent);
		if (cmp < 0)
			parent.left = entryOfKey;
		else
			parent.right = entryOfKey;
		elements++;
		fixAfterInsertion(entryOfKey);
		return null;
	}