lostinformation.java

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

//: generics/LostInformation.java
import java.util.*;

class Frob {}
class Fnorkle {}
class Quark<Q> {}
class Particle<POSITION,MOMENTUM> {}

public class LostInformation {
  public static void main(String[] args) {
    List<Frob> list = new ArrayList<Frob>();
    Map<Frob,Fnorkle> map = new HashMap<Frob,Fnorkle>();
    Quark<Fnorkle> quark = new Quark<Fnorkle>();
    Particle<Long,Double> p = new Particle<Long,Double>();
    System.out.println(Arrays.toString(
      list.getClass().getTypeParameters()));
    System.out.println(Arrays.toString(
      map.getClass().getTypeParameters()));
    System.out.println(Arrays.toString(
      quark.getClass().getTypeParameters()));
    System.out.println(Arrays.toString(
      p.getClass().getTypeParameters()));
  }
} /* Output:
[E]
[K, V]
[Q]
[POSITION, MOMENTUM]
*///:~