I have to write a program that takes a student ID and a number as input and then lowers all student notes by that that number except for one student based on the inputed ID. Here's what i mean: String = "Simon, 12345, 75\n Nick, 23456, 85\n Frank, 34567, 97\n

there's the students' names then their id and then their grade. i have to grab one ID as input and keep that student's grade intact but lower all the other grades by the inputed number.

System.out.print("Quel est le matricule de la note à conserver ? ");
                    String matricule = Keyboard.readString();
                    System.out.print("Combien voulez-vous enlever ? ");
                    int baisse = Keyboard.readInt();
                    
                    String temporaireD = "";
                    int débutÉlève = 0;
                    int finÉlève = 0;
                    
                    for (débutÉlève = 0; débutÉlève < notesDéchiffrées.length(); débutÉlève = finÉlève   1){
                        finÉlève = notesDéchiffrées.indexOf('\n', débutÉlève);
                        String noteÉlève = notesDéchiffrées.substring(notesDéchiffrées.lastIndexOf(", "), finÉlève);
                        
                        if (notesDéchiffrées.indexOf(matricule) == -1){
                            int note = Integer.parseInt(noteÉlève);
                            note = note - baisse;
                            String noteString = String.valueOf(note);
                            String nouvelÉlève =  notesDéchiffrées.substring(débutÉlève, finÉlève);
                        }
                        else{
                            String bonÉlève = notesDéchiffrées.substring(débutÉlève, finÉlève);
                            continue;
                        }
                        
                    }

CodePudding user response：

public static void decreaseGrade(String studentId, int reduction) {
   String studentRecord = "Simon, 12345, 75\n Nick, 23456, 85\n Frank, 34567, 97\n";
   String[] csvArray = studentRecord.split("\n");
   for(String student : csvArray) {
         String[] studentAttributes = student.split(", ");
         String name = studentAttributes[0].trim();
         String id = studentAttributes[1].trim();
         Integer grade = Integer.valueOf(studentAttributes[2].trim());
         if (!studentId.equals(id)) {
             grade -= reduction;
         }
         System.out.println("Name: "   name   ", ID: "   id   ", Grade: "   grade);
   }
}

CodePudding user response：

The code seen in Answer by kladderradatsch looks correct. Here is an alternative using objects, streams, and lambdas, for fun.

Set the inputs.

String targetId = "23456";
int reduction = 10;

String input =
        """
        Simon, 12345, 75
        Nick, 23456, 85
        Frank, 34567, 97
        """;

Define a record to hold each student's info.

record Student( String name , String id , int grade ) { }

Process the input data to get a list of student objects.

List < Student > students =
        Arrays
                .stream(
                        input.split( "\n" )
                )
                .map(
                        row -> {
                            String[] fields = row.split( ", " );
                            return new Student(
                                    fields[ 0 ] ,                     // name
                                    fields[ 1 ] ,                     // id
                                    Integer.parseInt( fields[ 2 ] )   // grade
                            );
                        }
                )
                .toList();

Process that list of student objects, this time replacing each student object with a new student object having a grade reduced except for our one target student ID where the grade remains unmodified. A ?: ternary statement is used here in lieu of an if statement.

List < Student > studentsRevised =
        students
                .stream()
                .map(
                        student ->
                                student.id.equals( targetId )
                                        ? student
                                        : new Student( student.name , student.id , student.grade - reduction )
                )
                .toList();

Dump to console.

System.out.println( "input = "   input );
System.out.println( "students = "   students );
System.out.println( "studentsRevised = "   studentsRevised );

When run. Notice that Nick keeps his grade while the other two are reduced.

input = Simon, 12345, 75
Nick, 23456, 85
Frank, 34567, 97

students = [Student[name=Simon, id=12345, grade=75], Student[name=Nick, id=23456, grade=85], Student[name=Frank, id=34567, grade=97]]
studentsRevised = [Student[name=Simon, id=12345, grade=65], Student[name=Nick, id=23456, grade=85], Student[name=Frank, id=34567, grade=87]]