Java:如何在接口层次结构中返回声明的类型？

Question

我有一个类似于 - 的接口层次结构

interface Type
{
    Type copy();
};

interface SubType extends Type
{
};

interface SubSubType extends SubType
{
};

还有一个具体的课程

public class Concrete implements SubSubType
{
    @Override public Concrete copy() { return new Concrete(); }
}

我希望能够在Type上调用copy()并获取Type返回,在SubType上调用copy()并获取SubType,等等.这是否可以实现？可能有仿制药？

提前致谢.

Answer 1

像这样:

public interface Type { 
  public Type copy();
}

public interface SubType extends Type { 
  public SubType copy();
}

public class Concrete implements Type { 
  @Override
  public Concrete copy() {
    return new Concrete();
  }
}

public class SubConcrete implements SubType {
  @Override
  public SubConcrete copy() {
    return new SubConcrete();
  }
}

public static void main(String[] args) {
  Type    type    = new Concrete();
  SubType subType = new SubConcrete();

  Type    newType    = type.copy();
  SubType newSubType = subType.copy();
}