importjava.util.Arrays;importjava.util.List;importjava.util.stream.Collectors;publicclassMapExample{publicstaticvoidmain(String[]args){List<String>strings=Arrays.asList("apple","banana","cherry");List<String>uppercaseStrings=strings.stream().map(String::toUpperCase).collect(Collectors.toList());Syste...
map操作,是把一个Stream中的每一个元素,都执行map中的函数操作,得到一个新的Stream。 map函数接受一个函数作为入参,可以是一个写好的函数,也可以是一个lambda表达式的函数。 使用: importjava.util.Arrays;importjava.util.List;importjava.util.stream.Collectors;publicclassStreamMapExample {publicstaticvoidmain(...
import java.util.stream.Collectors;publicclassStreamMapExample2 {publicstaticvoidmain(String[] args) { List<Integer> numbers = Arrays.asList(1,2,3,4,5);//使用 map 将每个数字加倍List<Integer> doubledNumbers =numbers.stream() .map(n-> n *2) .collect(Collectors.toList()); System.out.pr...
In the next example we map a custom method on a stream of strings. Main.java import java.util.stream.Stream; void main() { var words = Stream.of("cardinal", "pen", "coin", "globe"); words.map(JavaStreamMapEx3::capitalize).forEach(System.out::println); } String capitalize(String ...
下面是一个使用Stream生成Map的示例代码: importjava.util.List;importjava.util.Map;importjava.util.stream.Collectors;publicclassStreamToMapExample{publicstaticvoidmain(String[]args){// 学生信息列表List<Student>students=List.of(newStudent(1,"Alice"),newStudent(2,"Bob"),newStudent(3,"Charlie"));//...
package com.example.log.stream.test; import com.example.log.stream.entity.Student; import java.util.List; import java.util.Set; import java.util.stream.Collectors; /** * 测试map方法 * @date 2022/11/30 21:25 */ public class TestMap2 { public static void main(String[] args) { List<...
3. Stream map() Examples Let us see a few more examples to understand it even better. Example 1: Converting a Stream of Strings to a Stream of Integers In this example, we will convert aStream<String>toStream<Integer>. Here themapper functionInteger::valueOf()takes one string from the ...
words.add("World");List<String>characters=words.stream().map(string->string.split("")).flatMap(Arrays::stream).distinct().collect(Collectors.toList());System.out.println("characters:"+characters); The output is like following. characters:[H, e, l, o, W, r, d] ...
原因是声明List集合时有的值为空(如图),但是HashMap中k,v是可以存null值的。 解决方法:在转换流中加上判空,即便value为空,依旧输出。(与上面方法三相同) 代码语言:javascript 代码运行次数:0 运行 AI代码解释 Map<String,List<String>>map=list.stream().collect(Collectors.toMap(Person::getId,p->{List<St...
一、回顾Stream管道流map的基础用法 最简单的需求:将集合中的每一个字符串,全部转换成大写! 代码语言:javascript 代码运行次数:0 运行 AI代码解释 List<String>alpha=Arrays.asList("Monkey","Lion","Giraffe","Lemur");//不使用Stream管道流List<String>alphaUpper=newArrayList<>();for(String s:alpha){alpha...