Le tri des élèves par leur nom et le score à l'aide d'un tableau

Je pense que vous devriez changer votre dernière ligne compareTo comme ci-dessous:

    return (new Integer(examScore)).compareTo((new Integer(s.examScore));

ou

    return Integer.valueOf(examScore).compareTo(Integer.valueOf(s.examScore));

Cela permettra de comparer les deux valeurs et retourner en conséquence.

EDIT:

Quelques corrections dans votre programme:

1. Ajouter un toString() méthode dans votre Student classe:

   @Override
   public String toString(){
   retour prenom + " "+ nom +" : "+examScore;
   }

2. Mise à jour de la main() méthode d'application comme ci-dessous:

   public static void main(String[] args) throws Exception {
   Scanner aScanner = new Scanner(
   new FileReader("src//chapt11//ch11AS8data.txt"));
   System.out.println("Welcome to the Student Scores Application.\n");
   int nStudent = 100;
   Student[] studentArray = new Student[nStudent];
   Scanner lineScanner = null;
   int counter = 0;
   while (aScanner.hasNext()) {
   lineScanner = new Scanner(aScanner.nextLine());
   String lastName = lineScanner.next();
   String firstName = lineScanner.next();
   int examScore = lineScanner.nextInt();
   System.out.println("Student " + counter + " " + firstName + " "
   + lastName + " " + +examScore);
   studentArray[counter++]=new Student(lastName, firstName, examScore);
   lineScanner.close();
   }
   for(int j = 0; j < counter; j++){  
   System.out.println(studentArray[j]);
   }
   //sort based on first name
   Arrays.sort(studentArray,0,counter, new Comparator<Student>(){
   @Override
   public int compare(Student s1, Student s2) {
   return s1.getFirstName().compareTo(s2.getFirstName());
   }
   });
   System.out.println("Students sorted by first name in ascending order");
   for(int j = 0; j < counter; j++){  
   System.out.println(studentArray[j]);
   }
   //sort based on score
   Arrays.sort(studentArray,0,counter, new Comparator<Student>(){
   @Override
   public int compare(Student s1, Student s2) {
   return Integer.valueOf(s1.getExamScore()).
   compareTo(Integer.valueOf(s2.getExamScore()));
   }
   });
   System.out.println("Students sorted by score in ascending order");
   for(int j = 0; j < counter; j++){  
   System.out.println(studentArray[j]);
   }
   //To compute the average:
   double sum = 0.0;
   for(int j = 0; j < counter; j++){  
   sum+=studentArray[j].getExamScore();
   }
   double average = (sum*1.0)/counter;
   System.out.println("Average Score = "+average );
   aScanner.close();
   }

Puisque c'est les devoirs, je ne suis pas vous donner la réponse ... Mais voici l'idée générale de ce que vous devriez être en train de ...

import java.io.FileReader;
import java.util.Scanner;
public class App {
public static void main( String[] args ) throws Exception {
//TODO Auto-generated method stub
Scanner aScanner = new Scanner( new FileReader( "src/scores.txt" ) );
System.out.println( "Welcome to the Student Scores Application." );
System.out.println();
Student[] studentArray;
String lastName;
String firstName;
int examScore = 0;
double average = 0;
int nStudent = 100;
studentArray = new Student[nStudent];
int counter = 0;
while( aScanner.hasNext() ) {
lastName = aScanner.next();
firstName = aScanner.next();
examScore = aScanner.nextInt();
studentArray[counter] = new Student( lastName, firstName, examScore );
System.out.println( "Student " + studentArray[counter].getFirstName() + " " +  studentArray[counter].getLastName() + "'s " + "Test Score is :" + studentArray[counter].getExamScore() );
++counter;
if( counter >= nStudent ) {
break;
}
}
}
static class Student implements Comparable<Student> {
private String firstName;
private String lastName;
private int examScore;
public Student( String firstName, String lastName, int examScore ) {
this.firstName = firstName;
this.examScore = examScore;
this.lastName = lastName;
}
//Get & Set Methods
public int getExamScore() {
return examScore;
}
public String getFirstName() {
return firstName;
}
public String getLastName() {
return lastName;
}
@Override
public int compareTo( Student s ) {
if( !lastName.equalsIgnoreCase( s.lastName ) ) {
return lastName.compareToIgnoreCase( s.lastName );
}
if( !firstName.equalsIgnoreCase( s.firstName ) ) {
return firstName.compareToIgnoreCase( s.firstName );
}
return examScore - s.examScore;
}
}
}