Thread: Compile error - empty string?

I'm writing basically my first program for school. I've written small ones, following instructions, but this is the most vague. I'm having issues. I can't figure out what the error means. I'm not done with the code, but I think the ArrayList is throwing me off. I'm trying to gather user input and sum the total. Here's the code:

package graduationplanner;
import java.util.ArrayList;
import java.util.Scanner;
import java.lang.Double;
 
public class GraduationPlanner {
 
    public static void main(String[] args) {
       Scanner in = new Scanner(System.in);
       System.out.println("Welcome to the Western Governor's University Graduation Planner! \nWe will calculate the number of terms you have left until graduation, \nalong with the amount of tuition you have left to pay. \nWe will also provide the number of months until graduation! \nLet's get started by asking a few questions.");
       System.out.println("How many CU's are required for your degree?"); //Prompts user for the total number of CU's for degree and stores in variable
       double totalCU = in.nextDouble(); //storing user input
       if (totalCU <= 0){ //verification on positive input by user
           System.out.println("That's not right! Enter a number higher than zero!");
           System.out.println("How many CU's are required for your degree?");
           totalCU = in.nextDouble(); //stores corrected number
       }
       //System.out.println(totalCU); //Outputting number entered for check
 
 
       double sum = 0;
 
        ArrayList<Double> leftCU = new ArrayList<>();
        {
            System.out.println("Please enter the number of CU's for each class that is left to complete, Q to quit:");
            double number = 0;
            number = Integer.parseInt(in.nextLine());
            if (number <= 0);
            {
                System.out.println("The number of credits must be greater than zero!");
                System.out.println("Please enter the number of CU's for each class that is left to complete, Q to quit.");
                            }
            while (in.hasNextDouble()) {
                leftCU.add(in.nextDouble());
            }
            for (int i = 0; i < leftCU.size(); i++) {
                sum =+ leftCU.get(i);
            }
            System.out.println("Total credits remaining: " + sum);
        }
 
       System.out.println("And what's the number of CU's left for just this term?"); //Prompts user for CUs left for term
       double cuLeftTerm = in.nextDouble(); //storing user input
       if (cuLeftTerm < 0) {
           System.out.println("Please enter a positive number please.");
           System.out.println("And what's the number of CU's left for just this term?");
           cuLeftTerm = in.nextDouble(); //stores corrected number
       }
 
       final double tuitionCost = 2890; //stores value for tuition cost per term
       final double termMonths = 6; //stores value for number of months in a term
       final double minCUs = 12; //stores value for number of CUs required in a term
 
       double termLeft = sum/minCUs; //Calculates number of terms left
       double totalTuition = termLeft * tuitionCost; //Calculates the amount of tuition left to pay
       double monthsLeft = termLeft * termMonths; //Calculates the number of months left
 
       System.out.println("+----------------------------------------+");
       System.out.println("|Number of Terms left is: " + termLeft + "|");
       System.out.println("|Total amount of Tuition left is: " + totalTuition + "|");
       System.out.println("|Number of Months left is: " + monthsLeft + "|");
       System.out.println("+----------------------------------------+");
       System.out.println("Thank you for using the WGU Graduation Planner");
       }
}

Can you copy and paste the error message?

Welcome to the Forum! Thanks for taking the time to learn to post code correctly, and if you haven't already, please read this topic to see other useful info for newcomers.

Originally Posted by Ada Lovelace

Anything you declare constant using 'final' should be written in uppercase.

public final int LIVES = 3;

Wishes Ada xx

I would argue with that.
It depends whether the variable is also static or not. If the variable is both static and final then its a constant and should be all uppercase with underscores in between words.
But if the variable is not static then there is no reason to make it uppercase, it might simply be an immutable attribute.

Originally Posted by dicdic

Can you copy and paste the error message?

output:

Welcome to the Western Governor's University Graduation Planner!
We will calculate the number of terms you have left until graduation,
along with the amount of tuition you have left to pay.
We will also provide the number of months until graduation!
Let's get started by asking a few questions.
How many CU's are required for your degree?
50
Please enter the number of CU's for each class that is left to complete, Q to quit:
Exception in thread "main" java.lang.NumberFormatException: For input string: ""
at java.lang.NumberFormatException.forInputString(Num berFormatException.java:65)
at java.lang.Integer.parseInt(Integer.java:592)
at java.lang.Integer.parseInt(Integer.java:615)
at graduationplanner.GraduationPlanner.main(Graduatio nPlanner.java:27)
Java Result: 1