My program wont catch an exception - try-catch

Question

Why wont this code catch the error if the user inputs a negative number?
public class Lab12 {
public static void main(String[] args) {
Course[] course1 = courses();
print(course1);
}//end main
public static Course[] courses() throws IllegalArgumentException{
Scanner input = new Scanner(System.in);
System.out.println("How many courses?");
int numCourses = input.nextInt();
Course[] array = new Course[numCourses];
int s = 0;
boolean b = true;
for(int i = 0; i<numCourses; i++){
System.out.println("Enter the course title.");
String t = input.nextLine();
t = input.nextLine();
System.out.println("Enter the corresponding major.");
String m = input.nextLine();
do{
try{
System.out.println("Enter the number of students taking this course.");
s = input.nextInt();
b = false;
}//end try block
catch(IllegalArgumentException ex){
System.out.println("Input error."+
"\nPlese enter a positive number for students.");}//end catch
}while(b);
//Right here I dont see why my try catch wont work
Course c = new Course(t,m,s);
array[i] = c;
}//end for loop
input.close();
return array;
}//end courses method
public static void print(Course[] c){
for(int i = 0; i<c.length; i++){
System.out.println("Course title: "+c[i].getTitle()+
"\nMajor: "+c[i].getMajor()+
"\nNumber of Students: "+c[i].getStudents());
}//end for loop
}//end
}//end lab12
Here is the class associated with the main:
public class Course {
private String title;
private String major;
private int students;
public Course(String t, String m, int s){
title = t;
major = m;
students = s;
if(students<0){
throw new IllegalArgumentException("Wrong Argument.");
}
//my instruction were to throw an exception in the constructor is this correct
}//end constructor method
public String getTitle(){
return title;
}//end get title
public String getMajor(){
return major;
}//end get major
public int getStudents(){
return students;
}//end get students
public void setTitle(String t){
title = t;
}//end set title
public void setMajor(String m){
major = m;
}//end set major
public void setStudents(int s){
students = s;
}//end set students
}//end Class Course

Answer 1

In order to catch an exception in Java, you need to surround the code that throws the exception in a try/catch block.
Change your main for loop to something like this:
for(int i = 0; i<numCourses; i++){
System.out.println("Enter the course title.");
String t = input.nextLine();
t = input.nextLine();
System.out.println("Enter the corresponding major.");
String m = input.nextLine();
// Need to declare the Course object outside of the do/while so that it stays
// in scope afterwards
Course c = null;
do{
try{
System.out.println("Enter the number of students taking this course.");
s = input.nextInt();
b = false;
// Create the Course here so that the try/catch will correctly catch
// the IllegalArgumentException
c = new Course(t,m,s);
}//end try block
catch(IllegalArgumentException ex){
System.out.println("Input error."+
"\nPlease enter a positive number for students.");
}//end catch
} while(b);
array[i] = c;
}//end for loop