这是什么Java成员变量？
What kind of Java member variable is this?
我想知道这是什么类型的成员变量：
public class Stone {
private Size size; // "Size" refers to a class.
我不知道这个成员变量到底是什么。我以前没有看到成员变量是 class 。好像用另一个class作为成员变量，这样对吗？
是Size类型的实例变量。非常好而且非常常见。
来自 Java 教程 Understanding Class Members:
When a number of objects are created from the same class blueprint,
they each have their own distinct copies of instance variables. In the
case of the Bicycle class, the instance variables are cadence, gear,
and speed. Each Bicycle object has its own values for these variables,
stored in different memory locations.
我想知道这是什么类型的成员变量：
public class Stone {
private Size size; // "Size" refers to a class.
我不知道这个成员变量到底是什么。我以前没有看到成员变量是 class 。好像用另一个class作为成员变量，这样对吗？
是Size类型的实例变量。非常好而且非常常见。
来自 Java 教程 Understanding Class Members:
When a number of objects are created from the same class blueprint, they each have their own distinct copies of instance variables. In the case of the Bicycle class, the instance variables are cadence, gear, and speed. Each Bicycle object has its own values for these variables, stored in different memory locations.