java - 类是否必须位于同一继承树上才能具有 Has-A 关系

Question

class Employee {
    private String name;
    void setName(String n) { name = n; }
    String getName() { return name; }
}
interface Mungeable {
    void doMunging();
}
public class MyApp implements Mungeable {
    public void doMunging() { ; }
    public static void main(String[] args) {
        Employee e = new Employee();
        e.setName("bob");
        System.out.print(e.getName());
    } 
}

以及可能的答案:

Which are true? (Choose all that apply.)
A. MyApp is-a Employee.
B. MyApp is-a Mungeable.
C. MyApp has-a Employee.
D. MyApp has-a Mungeable.
E. The code is loosely coupled.
F. The Employee class is well encapsulated.

在回答上述问题时，我选择了选项B、C、E和F

显然唯一正确的答案是B、E和F。为了使 MyApp 与 Employee 具有 Has-A 关系，两者必须位于同一继承树层次结构中。它是否正确？我认为如果一个类将对象作为成员，它会自动具有 Has-A 关系。

Answer 1

MyApp 没有 Employee，没有定义成员。 MyApp 有 main 方法，就是这样。根据下面的代码，MyApp has-a Employee。

public class MyApp implements Mungeable {
    public void doMunging() { ; }
    private Employee;
    public static void main(String[] args) {
        Employee e = new Employee();
        e.setName("bob");
        System.out.print(e.getName());
    } 
}