package com.bijian.test;/*** 两个元素的元组，用于在一个方法里返回两种类型的值*/
public class TwoTuple<A, B> {public final A first;public final B second;public TwoTuple(A a, B b) {this.first = a;this.second = b;}
}

package com.bijian.test;/*** 三个元素的元组，用于在一个方法里返回三种类型的值*/
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);this.third = c;}
}

package com.bijian.test;public class GoodsBean {private int goodsId;public int getGoodsId() {return goodsId;}public void setGoodsId(int goodsId) {this.goodsId = goodsId;}
}

package com.bijian.test;import java.util.ArrayList;
import java.util.List;/*** 元组辅助类，用于多种类型值的返回，如在分页的时候，后台存储过程既返回了查询得到的* 当页的数据（List类型），又得到了数据表中总共的数据总数（Integer类型），然后将这* 两个参数封装到该类中返回到action中使用* 使用泛型方法实现，利用参数类型推断，编译器可以找出具体的类型*/
public class TupleUtil {public static <A, B> TwoTuple<A, B> tuple(A a, B b) {return new TwoTuple<A, B>(a, b);}public static <A, B, C> ThreeTuple<A, B, C> tuple(A a, B b, C c) {return new ThreeTuple<A, B, C>(a, b, c);}// 测试public static void main(String[] args) {List<GoodsBean> goodsBeans = new ArrayList<GoodsBean>();for(int i = 1; i < 26; i++) {GoodsBean goodsBean = new GoodsBean();goodsBean.setGoodsId(i);goodsBeans.add(goodsBean);}Integer totalProperty = 47;
//      TupleUtil<List<GoodsBean>, Integer> tupleUtil = new TupleUtil<List<GoodsBean>, Integer>(goodsBeans, totalProperty);TwoTuple<List<GoodsBean>, Integer> twoTuple = TupleUtil.tuple(goodsBeans, totalProperty);List<GoodsBean> list = twoTuple.first;System.out.println(list);System.out.println(twoTuple.second);}
}

package com.bijian.test;import java.util.ArrayList;
import java.util.List;import org.apache.commons.lang3.tuple.Pair;public class TupleUtil2 {// 测试public static void main(String[] args) {List<GoodsBean> goodsBeans = new ArrayList<GoodsBean>();for(int i = 1; i < 26; i++) {GoodsBean goodsBean = new GoodsBean();goodsBean.setGoodsId(i);goodsBeans.add(goodsBean);}Integer totalProperty = 47;Pair<List<GoodsBean>, Integer> twoTuple = Pair.of(goodsBeans, totalProperty);List<GoodsBean> list = twoTuple.getLeft();System.out.println(list);System.out.println(twoTuple.getRight());}
}

package com.bijian.test;import org.apache.commons.lang3.tuple.Pair;public class PairTest {private Pair<Long, Long> pair = Pair.of(100l, 60l);public static void main(String[] args) {PairTest pairTest = new PairTest();pairTest.test1();pairTest.test2();}public void test1() {System.out.println("pair" + pair);  //pair(100,60)Pair<Long, Long> newPair = Pair.of(3000l, 30l);System.out.println("newPair" + newPair);  //newPair(3000,30)System.out.println(newPair != pair);  //trueSystem.out.println(pair.compareTo(newPair));  //-1
    }public void test2() {System.out.println("pair" + pair);  //pair(100,60)Pair<Long, Long> newPair = null;System.out.println("newPair" + newPair);  //newPairnullSystem.out.println(newPair != pair); //trueSystem.out.println(pair.compareTo(newPair));  //Exception in thread "main" java.lang.NullPointerException
    }
}