文件读取数据后，进行合并和计算

 

map对象转java对象

list分类

optional处理

public static class Student{
    public String getName() {
        return name;
    }

    public String getSubject() {
        return subject;
    }

    public Double getGrade() {
        return grade;
    }

     String name;
     String subject;
     Double grade;
     public Student(String name, String subject, Double grade){
         this.name= name;
         this.subject = subject;
         this.grade = grade;
     }


 }
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下面是函数的具体实现：

FileInputStream fi = new FileInputStream("/Users/xx/workPlace/Test/a.txt");
InputStreamReader isr = new InputStreamReader(fi);
BufferedReader br = new BufferedReader(isr);
String line="";
List<Student> studentList = new ArrayList<>();

while((line = br.readLine()) != null){
           String[] data = line.split(" ");
           Student student = new Student(data[0], data[1], Double.valueOf(data[2]));
           studentList.add(student);
        }
        Map<String, List<Student>> stringListMap = studentList.stream().collect(Collectors.groupingBy(Student::getName));
        stringListMap.forEach((k,v)->{
                    TestSu.Student st = v.stream().max((Comparator.comparing(Student::getGrade))).get();
                    Double avg = v.stream().mapToDouble(Student::getGrade).average().getAsDouble();
                    System.out.println(st.getName()+"最高分科目为:" + st.getSubject() + st.getGrade() + "，平均分=" + avg );
                });