在Java中测试开闭原理

Question

interface IFaculty{
    void admin();
}

class ITFac implements IFaculty{
    @Override
    public void admin() {
        System.out.println("IT Fac Admin");
    }
}

class MedFac implements IFaculty{
    @Override
    public void admin(){
        System.out.println("Med Fac Admin");
    }
}

class University{
    public void adminFaculty(IFaculty iFaculty){
        iFaculty.admin();
    }
}

代码：

public class Main {
    public static void main(String[] args) {
        University u1 = new University();
        u1.adminFaculty();   // cannot call this method without passing parameters
    }
}

但是我不能在不传递相关参数的情况下调用该方法：iFaculty的一个对象。但我不能这么做。有人知道如何从main方法调用adminaulfly（）吗？或者以任何方式调用adminafully()，并运行代码以给出相应的输出。？

谢谢你。

Answer 1

从您的问题来看，我假设您希望能够调用adminafully()，并且始终使用相同的教程。为此，不要将教程传递给方法，而是在Univerisity中保留一个引用。您还可以添加默认的教员。

class University {
  private IFaculty faculty;

  //default configuration of the university: it has a medical faculty
  public University() {
    this(new MedFac());
  }

  //allows to create a university with another faculty type
  public University( IFaculty faculty) {
    this.faculty = faculty;
  }

  public void adminFaculty(){
    faculty.admin();
  }
}

现在您可以这样使用它：

University medicalUni = new University();
medicalUni.adminFaculty();

University anotherMedicalUni = new University(new MedFac());
anotherMedicalUni.adminFaculty();

University itUni = new University(new ITFac());
itUni.adminFaculty();

请注意，您总是需要iaffault的实现，比如medfac或itfac。当然，我现在可以添加一个新的教员，而不必更改大学:

class TechFac implements IFaculty{
  @Override
  public void admin() {
    System.out.println("Tech Fac Admin");
  }
}

University techUni = new University(new TechFac());