List集合的stream（）各种方法的使用

List<Student1> list = new ArrayList<>();
 list.add(new Student1("测试", "男", 18));
 list.add(new Student1("开发", "男", 20));
 list.add(new Student1("运维", "女", 19));
 list.add(new Student1("DBA", "女", 22));
 list.add(new Student1("运营", "男", 24));
 list.add(new Student1("产品", "女", 21));
 list.add(new Student1("经理", "女", 25));
 list.add(new Student1("产品", "女", 21));
 
 //求性别为男的学生集合
 List<Student1> l1 = list.stream().filter(student1 -> student1.getSex().equals("男"))
 .collect(Collectors.toList());
 
 //map的key值true为男，false为女的集合
 Map<Boolean, List<Student1>> map = list.stream()
 .collect(partitioningBy(student1 -> student1.getSex().equals("男")));
 
 //求性别为男的学生总岁数
 Integer sum = list.stream().filter(student1 -> student1.getSex().equals("男")).mapToInt(Student1::getAge).sum();
 
 //按性别进行分组统计人数
 Map<String, Integer> map1 = list.stream()
 .collect(Collectors.groupingBy(Student1::getSex, Collectors.summingInt(p -> 1)));
 
 //判断是否有年龄大于25岁的学生
 boolean check = list.stream().anyMatch(student -> student.getAge() > 25);
 
 //获取所有学生的姓名集合
 List<String> l2 = list.stream()
 .map(Student1::getName).collect(Collectors.toList());
 
 //求所有人的平均年龄
 double avg = list.stream().collect(averagingInt(Student1::getAge));
 
 //求年龄最大的学生 两种方式
 Student1 s = list.stream().reduce((student1, student2) -> student1.getAge() > student2.getAge() ? student1:student2).get();
 Student1 stu = list.stream().collect(Collectors.maxBy(Comparator.comparing(Student1::getAge))).get();
 
 //按照年龄从小到大排序
 List<Student1> l3 = list.stream()
 .sorted(Comparator.comparing(Student1::getAge))
 .collect(Collectors.toList());
//年龄从大道=到小排序
 List<Student1> l = list.stream().sorted(Comparator.comparing(Student1::getAge).reversed())
 .collect(Collectors.toList());
 
 //求年龄最小的两个学生
 List<Student1> l4 = l3.stream().limit(2)
 .collect(Collectors.toList());
 
 //获取所有的名字，组成一条语句
 String str = list.stream().map(Student1::getName)
 .collect(Collectors.joining(",", "[", "]"));
 
 //获取年龄的最大值、最小值、平均值、求和等等
 IntSummaryStatistics intSummaryStatistics = list.stream()
 .mapToInt(Student1::getAge).summaryStatistics();