所有类都间接或直接的继承自Object
Object类提供了以下11个方法
protected Object clone() boolean equals(Object obj) protected void finalize() Class<?> getClass() //https://i.cnblogs.com/EditPosts.aspx?postid=10088790 int hashCode() void notify() void notifyAll() String toString() void wait() void wait(long timeout) void wait(long timeout, int nanos)