java - 以这种方式将子类转换为父类有意义吗？

Question

class Student{
}

class CollegeStudent extends Student{
}

我有一个 CollegeStudent 列表，我想将其转换为 Student 列表:

List<CollegeStudent> collegeStudents = getStudents();
List<Student> students = new ArrayList<Student>();
for(CollegeStudent s : collegeStudents){
     students.add(s);
}

这是实现目的的适当方法吗？目的是否合理？我想这样做的原因是我需要创建另一个类，该类将 Student 列表作为参数，而不是 CollegeStduent 列表。

Answer 1

没问题，但还有一些更短的方法:

// Using the Collection<? extends E> constructor:
List<Student> studentsA = new ArrayList<>(collegeStudents);
// Using Collections.unmodifiableList which returns
// an unmodifiable view of the List<CollegeStudent>
// as a List<Student> without copying its elements:
List<Student> studentsB = Collections.unmodifiableList(collegeStudents);
// Older versions of Java might require a type
// witness for Collections.unmodifiableList:
List<Student> studentsC = Collections.<Student>unmodifiableList(collegeStudents);