java8 按条件过滤集合详解编程语言

//黄色部分为过滤条件
list.stream().filter(user-> user.getId() > 5 && "1组".equals(user.group)).collect(Collectors.toList());

public class HelloWorld { 
 
    public static void main(String[] args) { 
        Random random = new Random(); 
        List<User> list = new ArrayList<>(); 
        for(int i=1;i<=20;i++) { 
            String group = (random.nextInt(3) + 1) + "组";//1-3组随机 
            User u = new User(i, "用户-" + i, group); 
            list.add(u); 
        } 
        System.out.println("过滤前：" + list); 
        //按条件过滤 
        List<User> filterList = list.stream().filter(user -> user.getId() > 5 && "1组".equals(user.group)).collect(Collectors.toList()); 
 
        System.out.println("过滤 后：" + filterList); 
    } 
    private static class User{ 
        Integer id; 
        String name; 
        String group; 
 
        public User(Integer id, String name, String group) { 
            this.id = id; 
            this.name = name; 
            this.group = group; 
        } 
 
        public Integer getId() { 
            return id; 
        } 
 
        public void setId(Integer id) { 
            this.id = id; 
        } 
 
        public String getName() { 
            return name; 
        } 
 
        public void setName(String name) { 
            this.name = name; 
        } 
 
        public String getGroup() { 
            return group; 
        } 
 
        public void setGroup(String group) { 
            this.group = group; 
        } 
 
        @Override 
        public String toString() { 
            return "User{" + 
                    "id=" + id + 
                    ", name='" + name + '/'' + 
                    ", group='" + group + '/'' + 
                    '}'; 
        } 
    } 
 
}

过滤前：[User{id=1, name='用户-1', group='2组'}, User{id=2, name='用户-2', group='1组'}, User{id=3, name='用户-3', group='2组'}, User{id=4, name='用户-4', group='2组'}, User{id=5, name='用户-5', group='3组'}, User{id=6, name='用户-6', group='1组'}, User{id=7, name='用户-7', group='3组'}, User{id=8, name='用户-8', group='2组'}, User{id=9, name='用户-9', group='1组'}, User{id=10, name='用户-10', group='1组'}, User{id=11, name='用户-11', group='2组'}, User{id=12, name='用户-12', group='2组'}, User{id=13, name='用户-13', group='2组'}, User{id=14, name='用户-14', group='2组'}, User{id=15, name='用户-15', group='2组'}, User{id=16, name='用户-16', group='3组'}, User{id=17, name='用户-17', group='1组'}, User{id=18, name='用户-18', group='1组'}, User{id=19, name='用户-19', group='1组'}, User{id=20, name='用户-20', group='3组'}] 
过滤 后：[User{id=6, name='用户-6', group='1组'}, User{id=9, name='用户-9', group='1组'}, User{id=10, name='用户-10', group='1组'}, User{id=17, name='用户-17', group='1组'}, User{id=18, name='用户-18', group='1组'}, User{id=19, name='用户-19', group='1组'}]