Java 如何同时返回多个不同类型

//: net/mindview/util/TwoTuple.java（Java编程思想_代码_目录）
package net.mindview.util; 
public 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 + ")";
 }
}

//: net/mindview/util/ThreeTuple.java
package net.mindview.util;
 
public class ThreeTuple<A,B,C> extends TwoTuple<A,B> {
  public final C third;
  public ThreeTuple(A a, B b, C c) {
    super(a, b);
    third = c;
  }
  public String toString() {
    return "(" + first + ", " + second + ", " + third +")";
  }
}

//: net/mindview/util/FourTuple.java
package net.mindview.util;
 
public class FourTuple<A,B,C,D> extends ThreeTuple<A,B,C> {
  public final D fourth;
  public FourTuple(A a, B b, C c, D d) {
    super(a, b, c);
    fourth = d;
  }
  public String toString() {
    return "(" + first + ", " + second + ", " +
      third + ", " + fourth + ")";
  }
}

//: net/mindview/util/FiveTuple.java
package net.mindview.util;
 
public class FiveTuple<A,B,C,D,E>
extends FourTuple<A,B,C,D> {
  public final E fifth;
  public FiveTuple(A a, B b, C c, D d, E e) {
    super(a, b, c, d);
    fifth = e;
  }
  public String toString() {
    return "(" + first + ", " + second + ", " +
      third + ", " + fourth + ", " + fifth + ")";
  }
}

//: generics/TupleTest.java
import net.mindview.util.*; 
class Amphibian {
}
class Vehicle {
}
 
public class TupleTest {
 static TwoTuple<String, Integer> f() {
  // Autoboxing converts the int to Integer:
  return new TwoTuple<String, Integer>("hi", 47);
 }
 static ThreeTuple<Amphibian, String, Integer> g() {
  return new ThreeTuple<Amphibian, String, Integer>(new Amphibian(), "hi",
    47);
 }
 static FourTuple<Vehicle, Amphibian, String, Integer> h() {
  return new FourTuple<Vehicle, Amphibian, String, Integer>(new Vehicle(),
    new Amphibian(), "hi", 47);
 }
 static FiveTuple<Vehicle, Amphibian, String, Integer, Double> k() {
  return new FiveTuple<Vehicle, Amphibian, String, Integer, Double>(
    new Vehicle(), new Amphibian(), "hi", 47, 11.1);
 }
 public static void main(String[] args) {
  TwoTuple<String, Integer> ttsi = f();
  System.out.println(ttsi);
  // ttsi.first = "there"; // Compile error: final
  System.out.println(g());
  System.out.println(h());
  System.out.println(k());
 }
}

import java.util.*;
public class Demo { 
    //方法1：返回list
    public static List<int[]> returnList(){
        List<int[]> list=new ArrayList<>();
        list.add(new int[]{1});
        list.add(new int[]{1, 2});
        list.add(new int[]{1, 2, 3});
        return list;
    }
 
    //方法2：返回Map，一个Map只能有一种数据类型
    public static Map<String, Integer> returnMap(){
        Map<String,Integer> map = new HashMap<>();
        map.put("age",1);  //”age“是key，类似于索引，1是索引对应的int值
        map.put("high",30);
        //System.out.println(map.get("age"));
        Map<String,int[]> map1 = new HashMap<>();
        map1.put("array", new int[]{1, 2, 3});
        //System.out.println(Arrays.toString(  map1.get("array") ));
        return map;
    }
 
    //方法3：一次性返回两种类型的数据，结合了Map和list
    public static List<Map> returnMapList(){
        Map<String,Integer> map = new HashMap<>();
        map.put("age",1);
        map.put("high",30);
        Map<String,int[]> map1 = new HashMap<>();
        map1.put("array", new int[]{1, 2});
        List<Map> listMap = new ArrayList<Map>();
        listMap.add(map);
        listMap.add(map1);
        return listMap; 
    } 
 
//测试代码
    public static void main(String[] args){
        //返回list
        List<int[]> list1 = returnList();
        System.out.println(Arrays.toString(list1.get(0)) + Arrays.toString(list1.get(1)) + Arrays.toString(list1.get(2)) + "\nreturnlist结束\n");
 
        //返回Map，一个Map只能有一种数据类型
        Map<String,Integer> mapTest = returnMap();
        System.out.println("age = " + mapTest.get("age") +"，   high = " + mapTest.get("high") +  "\nreturnMap结束\n");
 
        //一次性返回两种类型的数据，结合了Map和list
        List<Map> list2 = returnMapList();
        System.out.println(list2.get(0)  +" , " + list2.get(1)  + "\nreturnMapList结束");//list2.get(1)是数组的地址
        System.out.print("调用返回的int和int[]:");
        Map map0 = list2.get(0);
        Map map1 = list2.get(1);
        System.out.println( "age = " + map0.get("age") );
        System.out.println("array = " + Arrays.toString((int[]) map1.get("array")));
//      System.out.println(Arrays.toString((int[]) list2.get(1).get("array")));   //调用过程也可以这样写
    }
}