classtypecapture.java

来自「Thinking in JAVA第四版源代码」· Java 代码 · 共 30 行

//: generics/ClassTypeCapture.java

class Building {}
class House extends Building {}

public class ClassTypeCapture<T> {
  Class<T> kind;
  public ClassTypeCapture(Class<T> kind) {
    this.kind = kind;
  }
  public boolean f(Object arg) {
    return kind.isInstance(arg);
  }	
  public static void main(String[] args) {
    ClassTypeCapture<Building> ctt1 =
      new ClassTypeCapture<Building>(Building.class);
    System.out.println(ctt1.f(new Building()));
    System.out.println(ctt1.f(new House()));
    ClassTypeCapture<House> ctt2 =
      new ClassTypeCapture<House>(House.class);
    System.out.println(ctt2.f(new Building()));
    System.out.println(ctt2.f(new House()));
  }
} /* Output:
true
true
false
true
*///:~