Guava学习笔记：transfer of List<E> and Map<E>
package com.amg.test;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import com.google.common.base.Function;import com.google.common.collect.ImmutableList;import com.google.common.collect.ImmutableMap;import com.google.common.collect.Lists;import com.google.common.collect.Maps;public class collectTransform {public static Map<Integer, Double> getMapRMB() {Map<Integer, Double> map_rmb = ImmutableMap.of(1, 100.12, 2, 672.87, 3,358.45);return map_rmb;}public static Map<Integer, Double> getMapRMB2() {Map<Integer, Double> map_rmb = new HashMap<Integer, Double>();map_rmb.put(1, 100.12);map_rmb.put(2, 672.87);map_rmb.put(3, 358.45);return map_rmb;}public static List<Double> getListRMB2() {List<Double> list = Lists.newArrayList();list.add(100.12);list.add(672.87);list.add(358.45);return list;}public static List<Double> getListRMB() {ImmutableList<Double> list = ImmutableList.of(100.12, 672.87, 358.45);return list;}public static void main(String[] args) {// old methodMap<Integer, Double> rmbMap = getMapRMB2();Map<Integer, Double> usdMap = getMapUSD(getMapRMB2());for (int i = 1; i <= usdMap.size(); i++) {System.out.println("RMBMap:" + rmbMap.get(i) + "-" + usdMap.get(i) + ":USDMap" );}List<Double> rmbList = getListRMB2();List<Double> usdList = getListUSD(getListRMB2());for (int i = 0; i < usdList.size(); i++) {System.out.println("RMBList:" + rmbList.get(i) + "-" + usdList.get(i) + ":USDList" );}System.out.println("-------------------------");// new methodList<Double> rmbPriceList = getListRMB();List<Double> usdPriceList = Lists.transform(rmbPriceList,new Function<Double, Double>() {double rate = 6.12;@Overridepublic Double apply(Double from) {return from / rate;}});for (Double d : usdPriceList) {System.out.println("guavaFinalList:" + d);}Map<Integer, Double> rmbPriceMap = getMapRMB();Map<Integer, Double> usdPriceMap = Maps.transformValues(rmbPriceMap,new Function<Double, Double>() {double rate = 6.12;@Overridepublic Double apply(Double from) {return from / rate;}});for (Integer d : usdPriceMap.keySet()) {System.out.println("guavaFinalMap key:" + d + ",value:"+ usdPriceMap.get(d));}}public static List<Double> getListUSD(List<Double> listRmb) {List<Double> listUsd = new ArrayList<Double>();for (int i = 0; i < listRmb.size(); i++) {double rate = 6.12;double rmbPrice = listRmb.get(i);double usdPrice = rmbPrice / rate;listUsd.add(usdPrice);}return listUsd;}public static Map<Integer, Double> getMapUSD(Map<Integer, Double> mapRmb) {Map<Integer, Double> map_usd = new HashMap<Integer, Double>();for (int i = 1; i <= mapRmb.size(); i++) {double rate = 6.12;double rmbPrice = mapRmb.get(i);double usdPrice = rmbPrice / rate;map_usd.put(i, usdPrice);}return map_usd;}}?
运行结果：
RMBMap:100.12-16.359477124183005:USDMapRMBMap:672.87-109.94607843137254:USDMapRMBMap:358.45-58.57026143790849:USDMapRMBList:100.12-16.359477124183005:USDListRMBList:672.87-109.94607843137254:USDListRMBList:358.45-58.57026143790849:USDList-------------------------guavaFinalList:16.359477124183005guavaFinalList:109.94607843137254guavaFinalList:58.57026143790849guavaFinalMap key:1,value:16.359477124183005guavaFinalMap key:2,value:109.94607843137254guavaFinalMap key:3,value:58.57026143790849
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