这是《Thinking in JAVA》里的一幅图吧？根本不是UML图。作者不是说得很清楚吗？ The dotted boxes represent interfaces, the dashed boxes represent abstract classes, and the solid boxes are regular (concrete) classes. The dotted-line arrows indicate that a particular class is implementing an interface (or in the case of an abstract class, partially implementing that interface). The solid arrows show that a class can produce objects of the class the arrow is pointing to. For example, any Collection can produce an Iterator...点线框表示接口，虚线框表示抽象类，实线框表示普通类。点线箭头指明某个类实现某个接口（对于抽象类则是部分实现该接口）。实箭头表示一个类可以产生其所指的类的对象，比如，Collection可以产生Iterator等...
The dotted boxes represent interfaces, the dashed boxes represent abstract classes, and the solid boxes are regular (concrete) classes. The dotted-line arrows indicate that a particular class is implementing an interface (or in the case of an abstract class, partially implementing that interface). The solid arrows show that a class can produce objects of the class the arrow is pointing to. For example, any Collection can produce an Iterator...点线框表示接口，虚线框表示抽象类，实线框表示普通类。点线箭头指明某个类实现某个接口（对于抽象类则是部分实现该接口）。实箭头表示一个类可以产生其所指的类的对象，比如，Collection可以产生Iterator等...