java8對集合的處理

public static void main(String[] args) {
List<Student> list = Lists.newArrayList();
list.add(new Student("測試", "男", 18));
list.add(new Student("開發", "男", 20));
list.add(new Student("運維", "女", 19));
list.add(new Student("DBA", "女", 22));
list.add(new Student("運營", "男", 24));
list.add(new Student("產品", "女", 21));
list.add(new Student("經理", "女", 25));
list.add(new Student("產品", "女", 21));

//求性別為男的學生集合
List<Student> l1 = list.stream().filter(student -> student.sex.equals("男")).collect(toList());

//map的key值true為男，false為女的集合
Map<Boolean, List<Student>> map = list.stream().collect(partitioningBy(student -> student.getSex().equals("男")));

//求性別為男的學生總歲數
Integer sum = list.stream().filter(student -> student.sex.equals("男")).mapToInt(Student::getAge).sum();

//按性別進行分組統計人數
Map<String, Integer> map = list.stream().collect(Collectors.groupingBy(Student::getSex, Collectors.summingInt(p -> 1)));

//判斷是否有年齡大於25歲的學生
boolean check = list.stream().anyMatch(student -> student.getAge() > 25);

//獲取所有學生的姓名集合
List<String> l2 = list.stream().map(Student::getName).collect(toList());

//求所有人的平均年齡
double avg = list.stream().collect(averagingInt(Student::getAge));

//求年齡最大的學生
Student s = list.stream().reduce((student, student2) -> student.getAge() > student2.getAge() ? student:student2).get();

Student stu = list.stream().collect(maxBy(Comparator.comparing(Student::getAge))).get();

//按照年齡從小到大排序
List<Student> l3 = list.stream().sorted((s1, s2) -> s1.getAge().compareTo(s2.getAge())).collect(toList());

//求年齡最小的兩個學生
List<Student> l4 = l3.stream().limit(2).collect(toList());

//獲取所有的名字，組成一條語句
String str = list.stream().map(Student::getName).collect(Collectors.joining(",", "[", "]"));

//獲取年齡的最大值、最小值、平均值、求和等等
IntSummaryStatistics intSummaryStatistics = list.stream().mapToInt(Student::getAge).summaryStatistics();
System.out.println(intSummaryStatistics.getMax());
System.out.println(intSummaryStatistics.getCount());
}

@Data
@AllArgsConstructor
static class Student{
String name;
String sex;
Integer age;

}