Format Exception in input string (Java)

Question

I am writing an appointment program in Java and am coming across an error which is "Exception in thread "main" java.lang.NumberFormatException: For input string : "quit" " For the following lines :

Exception in thread "main" java.lang.NumberFormatException: For input string: "quit"
at java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)
at java.lang.Integer.parseInt(Integer.java:449)
at java.lang.Integer.parseInt(Integer.java:499)
at AppointmentNew.main(AppointmentNew.java:24)

Also, when I make the selection in my code of printing a range of dates that the user inputs in the program it is printing out nothing, it is just going to the next line of "Make Choice ( 1: New, 2: Print Range, 3: Print All, quit):" It should print out the range of dates that the user inputs...

Here is the code I have :

import java.util.*;
import java.text.SimpleDateFormat;
import java.util.Date;

public class AppointmentNew 
{
public static void main (String[] args)
{
  ArrayList<String> list = new ArrayList<String>();
  Scanner stdin = new Scanner(System.in);
  String choice = "";
  int choiceNum = 0;
  String date = "";
  String descrip = "";
  int type = 0;
  String typeChose = "";

  System.out.println("Welcome to Appointment App!\n");
  System.out.println("\t============================");

  do
  {
     System.out.print("\n\tMake Choice (1: New, 2: Print Range, 3: Print All, 4: Quit) ");
     choice = stdin.nextLine();
     choiceNum = Integer.parseInt(choice);

     if (choiceNum == 1)
     {
        System.out.print("\n\n\tEnter New Appointment Date in mm/dd/yyyy format: ");
        date = stdin.nextLine();

        System.out.print("\n\n\tEnter New Appointment Description: ");
        descrip = stdin.nextLine();

        System.out.print("\n\n\tEnter Type (1 = Once, 2 = Daily, 3 = Monthly): ");
        type = stdin.nextInt();
        stdin.nextLine();

        if (type == 1)
        {
           Once once = new Once(date, descrip);
           typeChose = "One-Time";
        }
        else if (type == 2)
        {
           Daily daily = new Daily(date, descrip);
           typeChose = "Daily";
        }
        else
        {
           Monthly monthly = new Monthly(date, descrip);
           typeChose = "Monthly";
        }
        String stringToAdd = "";
        stringToAdd = (date + " : \"" + descrip + "\", " + typeChose);
        list.add(stringToAdd);

        System.out.println("\n\n\tNew " + typeChose + " Appointment Added for " + date + "\n");
        System.out.println("\t============================\n");


     }

     if (choiceNum == 2)
     {
        System.out.print("\n\n\tEnter START Date in mm/dd/yyyy format: ");
        SimpleDateFormat sdf = new SimpleDateFormat("mm/dd/yyyy");
        Date lowDate = sdf.parse(stdin.nextLine());
        System.out.print("\n\n\tEnter END Date in mm/dd/yyyy format: ");
        Date highDate = sdf.parse(stdin.nextLine());  

        for(int i = 0; i < list.size(); i++)
        {
           int dateSpot = list.get(i).indexOf(" ");
           String currentDate = list.get(i);
           currentDate.substring(0, dateSpot);  

           if (currentDate.compareTo(lowDate) >= 0 && currentDate.compareTo(highDate) <= 0)
           {
              System.out.println("\n\t" + list.get(i));   
           }
        }
     }

     if (choiceNum == 3)
     {
        for(int i = 0; i < list.size(); i++)
        {
           System.out.println("\n\t" + list.get(i));     
        }
     }

  }while (choiceNum != 4);      
 }
}

Thank you in advance for any advice or help that is given!

Answer 1

What you need to do is change the way you get input. I'm not going to change the logic in your code so just use this method instead.

  public static Integer getNextInteger(Scanner stdin) {
    String line = null;
    int parsed = 0;
    while ((line = stdin.nextLine()) != null) {
      try {
        parsed = Integer.parseInt(line);
        break;
      } catch (NumberFormatException e) {
        // Throw error message to user.
      }
    }
    return parsed;
  }

You could also externalize your whole menu into a function and use the return value for the rest of your code.

public int generateMenuAndGetChoice(Scanner stdin) {
  System.out.println("Make Choice ( 1: New, 2: Print Range, 3: Print All, quit): ");
  while (true) { //Keep trying until we get correct input.
    String input = stdin.nextLine().trim(); // To deal with extra spaces.
    if (input.equals("1") || input.equalsIgnoreCase("new")) {
      return 1;
    } else if (input.equals("2") || input.equalsIgnoreCase("print range")) {
      return 2;
    } else if (input.equals("3") || input.equalsIgnoreCase("quit")) {
      return 3;
    } else {
      //Throw error to user possibly reshow menu options as well after error.
    }
  }
}

You are adding a giant string to list and then trying to get a date out of it. Moreover you are doing a String comparison with the 'dates' instead of a date comparison. This is probably why you are getting no output.

Replace everywhere you get a date such as below:

System.out.print("\n\n\tEnter START Date in mm/dd/yyyy format: ");
String lowDate = stdin.nextLine();

with this:

System.out.print("\n\n\tEnter START Date in mm/dd/yyyy format: ");
SimpleDateFormat sdf = new SimpleDateFormat("mm/dd/yyyy");
Date lowDate = sdf.parse(stdin.nextLine());

and then compare dates using Dates.compareTo().

Note: that your entire program relies on CORRECT input by the user. This will most definitely not be the case. Use try-catch and the Scanners hasNextInt() and such methods to ensure that you always get correct input from the user.

Answer 2

Here's what i think, you should modify the code as mentioned here :

System.out.print("\n\tMake Choice ( 1: New, 2: Print Range, 3: Print All, **4: quit**): ");
choice = stdin.nextLine();
choiceNum = Integer.parseInt(choice);

Now check the while loop condition as :

while (choiceNum != 4);

This is one of the way to solve your problem. java.lang.NumberFormatException occurs when you are attempting convert a string to numeric type, but string in not in appropriate format.

Java API

Update : The above mentioned solution will work fine if the user provide input in appropriate format. It will throw NumberFormatException if user provides any other string which not in format.To make the code error free , you can do something like this :

try{
    choiceNum = Integer.parseInt(choice);
   }catch(NumberFormatException e){
        System.out.println("Please provide correct input");
   }

Then you will be able to avoid NumberFormatException.

Answer 3

choiceNum = Integer.parseInt(choice);

Here you are passing quit as an input string. So it is throwing number format on this line.

Answer 4

For input string : "quit"

choiceNum = Integer.parseInt(choice);

would give

java.lang.NumberFormatException

since choice(="quit") is not an integer