Java8语法糖List＜Integer＞，List＜String＞，List＜Long＞，String之间互转

public class Test {
    public static void main(String[] args) {
        List integerList = new ArrayList<>();
        integerList.add(1);
        integerList.add(2);
        integerList.add(3);
        // List 转为 List
        List stringList = integerList.stream().map(String::valueOf).collect(Collectors.toList());
        System.out.println("List 转为 List=====>" + stringList);
 
        //List 转为 String 以逗号分隔
        String str = String.join(",", stringList);
        System.out.println("List 转为 String 以逗号分隔====>" + str);
 
        //List 转为 List
        List integerList1 = stringList.stream().map(Integer::valueOf).collect(Collectors.toList());
        System.out.println("List 转为 List====>" + integerList1);

        //List转List
        List longList = stringList.stream().map(s -> Long.parseLong(s.trim())).collect(Collectors.toList());
        System.out.println("List 转为 List====>" + longList);
    }
}