1.
//学生类
import lombok.Data;@Data
public class Student{private String stuId;private String name;private String age;private String sex;}2.
//测试类
public class Test {public static void main(String[] args) {// 创建学生ListList<Student> list = createStudentList();// 1.获取value为Student对象，key为学生ID的MapgetStudentObjectMap(list);// 2.获取value为学生姓名，key为学生ID的MapgetStudentNameMap(list);// 3.获取学生姓名ListgetStudentNameList(list);//4.List中删除学生id = 1的对象list.removeIf(student -> student.getStuId().equals(1));//5.如果StudentId为Long类型如何转？Map<String, String> mapStr = list.stream().collect(Collectors.toMap(student -> student.getStuId().toString(), student -> JSON.toJSONString(student)));//6.根据List中Student的学生姓名排序Collections.sort(list, (o1, o2) -> {if (o1.getName().compareTo(o2.getName()) > 0) {return 1;} else if (o1.getName().compareTo(o2.getName()) < 0) {return -1;} else {return 0;}});//7.List遍历List<String> listStr = new ArrayList<>();List<Student> listStu = new ArrayList<>();listStr.forEach(studentStr -> {listStu.add(JSON.parseObject(studentStr, Student.class));});//List根据某个字段过滤、排序listStu.stream().filter(student -> student.getSex().equals("女")).sorted(Comparator.comparing(Student::getName)).collect(Collectors.toList());//List根据某个字段分组Map<String,List<Student>> sexGroupMap = listStu.stream().collect(Collectors.groupingBy(Student::getSex));//如果Map中多个名称相同，则studentId用逗号间隔Map<String,String> studentNameIdMap = listStu.stream().collect(toMap(Student::getName,Student::getStuId,(s,a)->s+","+a));}public static List<Student> createStudentList() {List<Student> list = new ArrayList<Student>();Student lily = new Student();lily.setStuId("1");lily.setName("lily");lily.setAge("14");lily.setSex("女");Student xiaoming = new Student();xiaoming.setStuId("2");xiaoming.setName("xiaoming");xiaoming.setAge("15");xiaoming.setSex("男");list.add(lily);list.add(xiaoming);return list;}public static Map<Object, Object> getStudentObjectMap(List<Student> list) {Map<Object, Object> map = list.stream().collect(Collectors.toMap(Student::getStuId, student -> student));map.forEach((key, value) -> {System.out.println("key:" + key + ",value:" + value);});return map;}public static Map<String, String> getStudentNameMap(List<Student> list) {Map<String, String> map = list.stream().collect(Collectors.toMap(Student::getStuId, Student::getName));map.forEach((key, value) -> {System.out.println("key:" + key + ",value:" + value);});return map;}public static List<String> getStudentNameList(List<Student> list) {List<String> result = list.stream().map(student -> student.getName()).collect(Collectors.toList());for (String name : result) {System.out.println("name:" + name);}return result;} }