importjava.util.ArrayList;importjava.util.HashMap;importjava.util.List;importjava.util.Map;publicclassMain{publicstaticvoidmain(String[]args){Map<String,Integer>map=newHashMap<>();map.put("apple",1);map.put("banana",2);map.put("orange",3);List<Fruit>fruitList=newArrayList<>();for(Map....
keyList2.forEach(System.out::println);// value 转 ListList<String> valueList=newArrayList<>(map.values());List<String> valueList2=map.values().stream().collect(Collectors.toList()); valueList.forEach(System.out::println); valueList2.forEach(System.out::println);// Iterator转ListList<K...
List<String> dataListTo = new ArrayList<>(); List<String> intersectionList = dataListFrom.stream().filter(item -> dataListTo.contains(item)).collect(toList()); 1. 2. 3. 10、Listto Map static Map<String, Map<String, Object>> toMap(List<Map<String, Object>> dataList, String uniKey...
2. Export Map Value to List... dragonfruit orange watermelon apple banana Java 8 – Map To List For Java 8, you can convert the Map into a stream, process it and returns it back as a List ConvertMapToList.java package com.mkyong; import java.util.HashMap; import java.util.List; i...
public static voidmain(String[]args){Map<Integer,String>map=newHashMap<>();map.put(10,"apple");map.put(20,"orange");map.put(30,"banana");map.put(40,"watermelon");map.put(50,"dragonfruit");System.out.println("\n1. Export Map Key to List...");List<Integer>result=map.entrySet...
4、Map<String,UserInfo> 转 List<String>、List<UserInfo> // 取Map中的所有value 结果:List<UserInfo> userInfoList = retMap.values().stream().collect(Collectors.toList()); // 取Map中所有key 结果:List<String> strList = retMap.keySet().stream().collect(Collectors.toList());...
使用Java8 stream后,用map做转换,参考代码片段如下: 方法一: 代码语言:javascript 复制 privateMap<String,Object>toMap(User user){Map<String,Object>map=newHashMap<>();map.put("username",user.getUsername());map.put("age",user.getAge());map.put("gender",user.getGender());returnmap;}List<Ma...
集合框架是Java编程语言中一组基本接口和实现类的集合，用于存储、操作和传输数据。它主要包括Collection接口、List接口、Set接口和Map接口等。2. List（列表）List是有序、可重复的集合，它继承自Collection接口。常见的List实现类有ArrayList、LinkedList和Vector。List通过索引（index）访问元素，允许元素重复。```java ...
Map<Long, User> map = userList.stream().collect(Collectors.toMap(User::getId, p -> p));这一步就是将userList 转换为key为id,value为User对象的map。 User::getId ===》 User对象的getId方法 p -> p ===》就是进来的是什么,最终就是什么,这里就是进来的是User对象,出去的也就是User...
import static java.util.stream.Collectors.collectingAndThen; import static java.util.stream.Collectors.toCollection; // 根据id去重 List<Person> unique = appleList.stream().collect( collectingAndThen( toCollection(() -> new TreeSet<>(comparingLong(Apple::getId))), ArrayList::new) ...