java - Java 的包含的 TreeSet 实现（源代码）缺失

Question

当我打开 TreeSet 类的源代码时，有以下代码：

public boolean contains(Object o) {
    return m.containsKey(o);
}

m 是一个 NavigableMap，它是一个接口。那么实施在哪里呢？它绝对不在 TreeSet 本身。

Answer 1

From the source for TreeSet:

TreeSet(NavigableMap<E,Object> m) {
    this.m = m;
}

public TreeSet() {
    this(new TreeMap<E,Object>());
}

So m should be a TreeMap (or possibly another implementation of NavigableMap if another class in the same package calls that constructor).