Java—stream以及集合框架使用

1) 编写Student类，主要属性包括学号、姓名、性别、班级
2) 编写Score类，主要属性包括：学号、课程名、分数
3) 模拟期末考试的成绩统计应用场景，要求
(1) 所有学生名单及对应科目成绩已经初始化在数组中
(2) 要求输出每门课程的所有学生的平均成绩。
(3) 输出某门课程的最高成绩，最低成绩
(4) 可以查询某个学生的所有成绩。

源代码

二、源程序
Score类
public class Score {private String studentID;private String course;private int grades;public Score(String studentID, String course, int grades) {this.studentID = studentID;this.course = course;this.grades = grades;}public String getStudentID() {return studentID;}public void setStudentID(String studentID) {this.studentID = studentID;}public String getCourse() {return course;}public void setCourse(String course) {this.course = course;}public int getGrades() {return grades;}public void setGrades(int grades) {this.grades = grades;}
}Student类
public class Student {private String studentID;private String studentName;private String sex;private String classID;public Student(String studentID, String studentName, String sex, String classID) {this.studentID = studentID;this.studentName = studentName;this.sex = sex;this.classID = classID;}public String getStudentID() {return studentID;}public void setStudentID(String studentID) {this.studentID = studentID;}public String getStudentName() {return studentName;}public void setStudentName(String studentName) {this.studentName = studentName;}public String getSex() {return sex;}public void setSex(String sex) {this.sex = sex;}public String getClassID() {return classID;}public void setClassID(String classID) {this.classID = classID;}
}Util类
public class Util {public static void getAverage(Score[] scores) {Set<String> set = new HashSet<>();for (Score score : scores)set.add(score.getCourse());for (String course : set)System.out.println(course + "平均成绩：" + Arrays.stream(scores).filter(x -> x.getCourse().equals(course)).mapToInt(Score::getGrades).summaryStatistics().getAverage());}public static void getMax(Score[] scores, String course) {IntSummaryStatistics statistics = Arrays.stream(scores).filter(x -> x.getCourse().equals(course)).mapToInt(Score::getGrades).summaryStatistics();System.out.println(course + "最高成绩：" + statistics.getMax());System.out.println(course + "最低成绩：" + statistics.getMin());}public static void getAllGrade(Score[] scores, Student[] students, String studentName) {String studentID = null;for (Student student : students)if (student.getStudentName().equals(studentName))studentID = student.getStudentID();for (Score score : scores)if (studentID.equals(score.getStudentID()))System.out.println(studentName + "  " + score.getCourse() + "成绩为：" + score.getGrades());}public static void main(String[] args) {Score[] scores = new Score[]{new Score("1", "math", 89), new Score("1", "english", 90), new Score("2", "math", 92), new Score("2", "english", 95)};Student[] student = new Student[]{new Student("1", "mary", "women", "1"), new Student("2", "john", "men", "1")};getAverage(scores);getMax(scores, "math");getAllGrade(scores, student, "john");}
}