Anyone smart enough?

Question

My program does not have any errors until compiling where it states:
java.lang.NullPointerException
     at project2.Collection.getNum(OrderProcessing.java:171)
     at project2.OrderProcessing.main(OrderProcessing.java:240)
so basically it doesn't like my print statement:
System.out.println("Student Num: "+ access2.getNum(counter));
It also points to my collection class (access2 is collection class) to the getNum method. Does anyone know what I'm doing wrong? Here's the full code:
abstract class Student {
protected double Id;
protected String Name;
protected int grade1, grade2, grade3;
public Student(double i, String n, int g1, int g2, int g3) {
Id = i;
Name = new String(n);
grade1 = g1;
grade2 = g2;
grade3 = g3;
public abstract String calcGrade(double avg);
public abstract double getNum();
public abstract String getName();
public abstract int getG1();
public abstract int getG2();
public abstract int getG3();
class UnderGrad extends Student {
public UnderGrad(double i, String n, int g1, int g2, int g3) {
super(i, n, g1, g2, g3);
public String calcGrade(double avg) {
if (avg >= 90.00)
return "A";
else if (avg >= 80.00)
return "B";
else if (avg >= 70.00)
return "C";
else
return "F";
public double getNum()
{ return Id; }
public String getName()
{ return Name; }
public int getG1()
{ return grade1; }
public int getG2()
{ return grade2; }
public int getG3()
{ return grade3; }
class Grad extends Student {
public Grad(double i, String n, int g1, int g2, int g3) {
super(i, n, g1, g2, g3);
public String calcGrade(double avg) {
if (avg >= 90.00)
return "A";
else if (avg >= 80.00)
return "B";
else
return "F";
public double getNum()
{ return Id; }
public String getName()
{ return Name; }
public int getG1()
{ return grade1; }
public int getG2()
{ return grade2; }
public int getG3()
{ return grade3; }
class Audit extends Student {
public Audit(double i, String n, int g1, int g2, int g3) {
super(i, n, g1, g2, g3);
public String calcGrade(double avg) {
if (avg >= 50.00)
return "U";
else
return "F";
public double getNum()
{ return Id; }
public String getName()
{ return Name; }
public int getG1()
{ return grade1; }
public int getG2()
{ return grade2; }
public int getG3()
{ return grade3; }
class Collection {
protected Student myArray[];
private int num = 0;
private int g1, g2, g3;
protected String studentType;
private double avg;
public Collection()
myArray = new Student[40];
void addCase(int studentType, double i, String n, int g1, int g2, int g3) {
switch (studentType)
case 0:
myArray[num] = new UnderGrad(i, n, g1, g2, g3);
num++;
break;
case 1:
myArray[num] = new Grad(i, n, g1, g2, g3);
num++;
break;
case 2:
myArray[num] = new Audit(i, n, g1, g2, g3);
num++;
break;
case 3:
// end of file
break;
default:
System.err.println("Letters from file have to be U, G, A, E");
double getNum(int num)
return myArray[num].getNum();
String getName(int num)
return myArray[num].getName();
double getAvg(int num)
avg = 0;
g1= myArray[num].getG1();
g2= myArray[num].getG2();
g3= myArray[num].getG3();
avg = (g1 + g2 + g3)/3;
return avg;
public class OrderProcessing
public static BufferedReader inFile;
public static StringTokenizer sTokenizer;
public static void main(String[] args) throws IOException
int record = 1;
Student access1[] = new Student[3];
Collection access2;
access2 = new Collection();
DecimalFormat percent = new DecimalFormat ("%");
String inputString, n, sT;
int value, g1, g2, g3, counter, studentType;
double avg, i;
inFile = new BufferedReader(new FileReader("C:/grades.txt"));
inputString = inFile.readLine();
while(inputString != "E") {
for(counter = 0; counter <=4; counter++) {
sTokenizer = new StringTokenizer (inputString,",");
sT = sTokenizer.nextToken();
i = Double.parseDouble(sTokenizer.nextToken());
n = sTokenizer.nextToken();
g1 = Integer.parseInt(sTokenizer.nextToken());
g2 = Integer.parseInt(sTokenizer.nextToken());
g3 = Integer.parseInt(sTokenizer.nextToken());
if (sT == "U")
studentType = 0;
access1[0] = new UnderGrad(i, n, g1, g2, g3);
else if (sT == "G")
studentType = 1;
access1[1] = new Grad(i, n, g1, g2, g3);
else if (sT == "A")
studentType = 2;
access1[2] = new Audit(i, n, g1, g2, g3);
else
studentType = 3;
access2.addCase(studentType, i, n, g1, g2, g3);
System.out.println("Category:");
System.out.println("Student Num: "+ access2.getNum(counter));
System.out.println("Student Name: "+ access2.getName(counter));
System.out.println("Course Average: "+ percent.format(access2.getAvg(counter)));
System.out.println("Passed Course: ");//+ access1.getNetAmt());
System.out.println("--------------------------------");
avg = access2.getAvg(counter);
record++;
inputString = inFile.readLine();
inFile.close();
}

Answer 1

>
My program does not have any errors untilcompiling
Nobody's program has any errors prior tocompiling.
I disagree. It can have design problems.And it can have all sorts of other problems too,
including errors. (Let's skip any semantic arguments
about whether a design problem is strictly speaking an
"error".) You just don't know about the errors yet.
I was making a joke, ...I understood that. But since others do read these threads I wanted to make it clear that syntactic errors are not the only source of problems with code.