Thread: Help with error on second run through array

I'm having some issues with entering data into my array. The first run through the loop has no issues...that I can see, but once I have entered the first batch of information I start getting Null Pointer Exception errors. Here is the exact error:
"Exception in thread "main" java.lang.NullPointerException at Employee.main(Employee.java:108)"
On the second run through the loop, if I try to add a second set of data, the NPE is on line 108. If I try to view the data it's on line 112. I can't figure out what variable is being considered null. Can anyone help?

public static void main(String[] args) {
 
		Scanner input = new Scanner(System.in);
		final int size = 100; //max array size
		int numEmployee=0; //number of array entries
		int i;
		int choice=0;
		Employee [] employeeData = new Employee[size]; //an array of objects
		employeeData[numEmployee] = new Employee();
 
		System.out.println("1. Enter new employee data");
		System.out.println("2. Display employee data");
		System.out.print("3. Quit \n=> ");
		choice = input.nextInt();
 
		while(choice!=3){
			if(choice == 1){
				employeeData[numEmployee].setFirstName(); //******line 108 NPE is here******
				numEmployee++;
			}else if(choice == 2){
				for(i = 0; i<numEmployee; i++);
				System.out.println(employeeData[i].getFirstName()); //******line 112 NPE is here******
			}else{
				System.out.println("Invalid entry. Please try again.");
			} //close if
			System.out.println("1. Enter new employee data");
			System.out.println("2. Display employee data");
			System.out.print("3. Quit \n=> ");
			choice = input.nextInt();
		} //close while
 
		System.out.println("You have quit.");
	} //close main

That's my problem. I don't know what is null at line 108. Nothing is null the first time I run through, so I don't understand why something is null the second time. Is there a way to find out what is being considered null?

If I'm not mistaken, I'm putting objects into my array with line 108...am I not? But if that's the case, I am getting the NPE because the entry is not being put into the array properly. Is that what you meant?

And according to my println, employeeData[numEmployee] is still null even after I've entered data. Though, numEmployee has been given a value of 1 like it was supposed to.

Sorry, not sure I understand what you mean. How do I add a call to the println?

Ah sorry, misunderstood what you wrote. That I know how to do.
so, to call the elements in the array I should write:
System.out.println(employeeData[numEmployee]); ?

But all I get is null as a result.

Sorry, this is my first time working with arrays, so it's all still pretty confusing to me.

Wow, I'm having a hard time accessing the forums right now. Anyway...

Okay, tried that and I got 'Employee@3c939d40' for the first entry and then I got null values. I'm assuming 99 null values since my array is 100 units in size. Though 'Employee@3c939d40' isn't the content I entered into the array.

So, I need to do something about all the extra null values in order to solve my problem?

Okay this is slowly starting to make sense, but how do I fix my NPE problem without putting data into all 100 slots? 100 is just the max number of slots the user has to work with, but they don't have to use them all.

So, if I move my employeeData[numEmployee] = new Employee(); object down into the loop, that should create a new object each time the user chooses 1.

Something like this:

employeeData[numEmployee] = new Employee();
employeeData[numEmployee].setFirstName();
numEmployee++;

It's almost there. The NPE error at line 108 is gone. I can enter as much info as I want. Now I've just got to deal with the NPE error at line 112 where the user chooses to view the data that has been entered.

Thank you so much for all this help. I really appreciate it.

Alright, thanks again. I should be able to figure it out at this point.

--- Update ---

I solved it! Who knew a ; could cause so much chaos, haha. I'll definitely remember all these troubleshooting tips you gave me