My bubble sort doesn't work, and does anyone know

Question

how to count and print the scores of a certain grade.... all the 90's with a's, all the 80's with b's etc.... This is my first java program with two classes. I've been messing with it for about 24hours over the last week. :O. Any suggestions?
import java.util.Scanner;
public class GradeSort {
     public static void main(String [] args){
          //Scanner keyboard = new Scanner(System.in);
          System.out.println("How many students took the test?");
          Scanner kbd = new Scanner(System.in);
          int NUM_STUDENTS = kbd.nextInt();
          double [] grades = new double[NUM_STUDENTS];//Assn array
          readReadingsInto(grades);
          System.out.printf( "\nThe average is %.3f%n", average(grades));
          print(grades);}
          private static void readReadingsInto(double [] array){
               Scanner keyboard = new Scanner(System.in);
               for (int i =0; i < array.length; i++) {
               System.out.print("enter grade # " + (i+1)+ "/" );
          array[i] = keyboard.nextInt();
     public static double average(double [] anArray){
          double sum = 0.0;
          for (double item : anArray){
               sum += item;
          return sum/anArray.length;
public static void bubbleSort ( double [] anArray )
for (double i = anArray.length-1; i > 0; i-- )
for ( int j = 0; j < i; j++ )
if ( anArray[j] > anArray[j+1] )
double temp = anArray[j];
anArray[j] = anArray[j+1];
anArray[j+1] = temp;}
public static void print(double [] arr) {
     for (int i = 0; i < arr.length; i++){
          Grade gRade = new Grade(arr);
          System.out.println("Reading #" + (i+1)+" " + arr[i] + " " + gRade.letter() );
          //Grade gRade = new Grade(reading);
          //System.out.println( gRade.letter() );
          //System.out.print ( grades[1] );
public class Grade {
     public static final double MIN = 0.0;
     public static final double MAX = 100.0;
     public Grade(double gRade){
          if (gRade < MIN || gRade > MAX){
               System.err.println("Grade(): bad argument recievived: " + gRade);
          } else {
               myValue = gRade;
public String letter(){
     if (myValue < MIN || myValue > MAX){ return "error";}
else if (myValue >= 90){return "A";}
else if (myValue >= 80){return "B";}
else if (myValue >= 70){return "C";}
else return "Fail";     }
private double myValue;

Answer 1

Let me see if I can fix the formatting for you. The bubble sort, isn't sorting? The print after the sort is in the same order as I input the data.
import java.util.Scanner;
public class GradeSort {
     public static void main(String [] args){
          //Scanner keyboard = new Scanner(System.in);
          System.out.println("How many students took the test?");
          Scanner kbd = new Scanner(System.in);
          int NUM_STUDENTS = kbd.nextInt();
          double [] grades = new double[NUM_STUDENTS];//Assn array
          readReadingsInto(grades);
          System.out.printf( "\nThe average is %.3f%n", average(grades));
          print(grades);}
          private static void readReadingsInto(double [] array){
               Scanner keyboard = new Scanner(System.in);
               for (int i =0; i < array.length; i++) {
               System.out.print("enter grade # " + (i+1)+ "/" );
          array[i] = keyboard.nextInt();
     public static double average(double [] anArray){
          double sum = 0.0;
          for (double item : anArray){
               sum += item;
          return sum/anArray.length;
public static void bubbleSort ( double [] anArray )
        for (double i = anArray.length-1; i > 0; i-- )
          for ( int j = 0; j < i; j++ )
              if ( anArray[j] > anArray[j+1] )
                    double temp = anArray[j];
                    anArray[j] = anArray[j+1];
                    anArray[j+1] = temp;}
public static void print(double [] arr) {
     for (int i = 0; i < arr.length; i++){
          Grade gRade = new Grade(arr);
          System.out.println("Reading #" + (i+1)+" " + arr[i] + " " + gRade.letter() );
          //Grade gRade = new Grade(reading);
          //System.out.println( gRade.letter() );
          //System.out.print ( grades[1] );
The other class is:
public class Grade {
     public static final double MIN = 0.0;
     public static final double MAX = 100.0;
     public Grade(double gRade){
          if (gRade < MIN || gRade > MAX){
               System.err.println("Grade(): bad argument recievived: " + gRade);
          } else {
               myValue = gRade;
public String letter(){
     if (myValue < MIN || myValue > MAX){ return "error";}
else if (myValue >= 90){return "A";}
else if (myValue >= 80){return "B";}
else if (myValue >= 70){return "C";}
else return "Fail";     }
private double myValue;