One- way associations(单向关联) In a one-way association the first class has a reference to an object of the second class, but the second class does not have a reference to an object of the first class 单向关联中,第一个类中有一个第二个类的对象的 引用,但第二个类中没有第一个类的对象的引用 UML indicates a one-way association with an arrow at the end of the association line Car Engine engine 1515 One-way Associations (单向关联) • In a one-way association, the first class has a reference to an object of the second class, but the second class does not have a reference to an object of the first class. – 单向关联中，第一个类中有一个第二个类的对象的 引用，但第二个类中没有第一个类的对象的引用 • UML indicates a one-way association with an arrow at the end of the association line. Car Engine -engine