一个简单的泛型（元组）

class E{}
 class F{}
 class TwoTuple<A,B> {
 public final A first;
 public final B second;
 public TwoTuple(A a,B b){
  first=a;
  second= b;
  
 }
 public  String toString(){
  return "("+first+"."+second+")";
 
  }
 }
 class ThreeTuple<A,B,C>{
 public final A first;
 public final B second;
 public final C third;
 public ThreeTuple(A a,B b,C c){
  first=a;
  second=b;
  third=c;
 }
 public String toString(){
  return "("+first+"."+second+"."+third+")";
  
 }
}
class FourTuple<A,B,C,D>{
 public final A first;
 public final B second;
 public final C third;
 public final D four;
 public FourTuple(A a,B b,C c,D d){
  first=a;
  second=b;
  third=c; 
  four=d;
 }
 public String toString(){
  return "("+first+"."+second+"."+"."+third+"."+four+")";
 }
}
public class Tuple{
 static TwoTuple<String,Integer> f(){
  return new TwoTuple<String,Integer>("hi",47);
 }
 static ThreeTuple<String,Integer,E> g(){
  return new ThreeTuple("how",48,new E());
 }
 static FourTuple<F,E,String,Integer> h(){
  return new FourTuple(new F(),new E(),"are",54);
  
 }
 public static void main(String[] args){

  TwoTuple<String,Integer> myTwoTuple=f();//其中不能写成TwoTuple  myTwoTuple=f();否则会报为初始化
  System.out.println(myTwoTuple);
 
  System.out.println(h());
  System.out.println(g());
 }
}

 当然上面的几个类也可以用继承机制来简化代码量。