covariantreturntypes.java

来自「java编程思想(第四版)书中原代码 ,对初学者很有用的东西」· Java 代码 · 共 20 行

//: generics/CovariantReturnTypes.java

class Base {}
class Derived extends Base {}

interface OrdinaryGetter {
  Base get();
}

interface DerivedGetter extends OrdinaryGetter {
  // Return type of overridden method is allowed to vary:
  Derived get();
}

public class CovariantReturnTypes {
  void test(DerivedGetter d) {
    Derived d2 = d.get();
  }
} ///:~