Stream实例使用

List list1 = Arrays.asList("Jack", "Mike", "Nicolas", "Nico", "Jimy","Tom");
List list2 = Arrays.asList(22, 3, 12, 56, 43);

String为字符串格式，Integer是

(1) 查询字母T开头的人名；

list1.stream().filter(s -> s.startsWith("T")).collect(Collectors.toList()).forEach(System.out::println);

(2)查询姓名长度小于等于4的人名；

list1.stream().filter(s -> s.length()<=4).collect(Collectors.toList()).forEach(System.out::println);

(3)将字母J开头的人名全部改为大写字母;

list1.stream().map(s -> s.replaceAll("j","J")).forEach(System.out::println);

(4)查询姓名最长的人名;

Optional g= list1.stream().max(Comparator.comparing(String::length));

(5)获得list2的最大值和最小值;

System.out.println(list2.stream().max(Integer::compareTo).get());
System.out.println(list2.stream().min(Integer::compareTo).get());

其基本格式如下

public class tec {
    public static void main(String[] args){
        List list1 = Arrays.asList("Jack", "Mike", "Nicolas", "Nico", "Jimy","Tom");
        List list2 = Arrays.asList(22, 3, 12, 56, 43);
        System.out.println(list2.stream().max(Integer::compareTo).get());
        System.out.println(list2.stream().min(Integer::compareTo).get());
    }
}