Simple while loop exercise but problem with stopping when empty line is typed.

**JavaN00b** · May 14th, 2011, 12:36 PM

Hi again, I'm sitting and learning about while loops and stuck at the first exercise it which says:

1.Write a sentinel lopp that repeatedly prompts the user for names. Once an empty line is typed, all names typed are displayed. For example:

Type a person's name (or an empty line to stop): Marty
Type a person's name (or an empty line to stop): Andrea
Type a person's name (or an empty line to stop): Stuart
Type a person's name (or an empty line to stop):
Welcome to all: Marty Andrea Stuart

The words written with bold is the user input. I've somehow gotten my code to work with adjustments.

import java.util.Scanner;
 
public class UserNames {
	public static void main(String[] args0){
		Scanner console = new Scanner(System.in);
 
		String users = "";
		String temp = "";
		System.out.println("Type a person's name (or an empty line to stop): ");
		temp = console.next();
 
		while(!temp.equals("V")){
 
			users += temp+" ";
			System.out.println("Type a person's name (or an empty line to stop):");
			temp = console.next();
 
		}		
		System.out.println("Welcome to all:"+users);
	}	
}

As you notice fast it's when you press V that the program stops. I'm wondering how I can make it so that it fits the description in the exercise with empty line.
In Eclipse I can't press space and then enter or just enter when the program is running. The cursor just moves to the next line and awaits input from the user who seem to be forced to type something except space or just enter.

Anyone got suggestions or know what I'm doing wrong? Thanks

**OutputStream** · May 14th, 2011, 02:57 PM

What you want to do is to check if the string is empty (i.e. it's length is equal to zero).
Check the following link, if you check the "Method Summary" table you will most likely find a method or two that you can use

String (Java Platform SE 6)

**Norm** · May 14th, 2011, 04:58 PM

Scanner methods are tricky. Some require something be entered and will skip over white space and the Enter key waiting for input.

Try different Scanner methods for reading the input. Perhaps nextLine() will work better.

**vanDarg** · May 14th, 2011, 05:12 PM

I would alter the condition of the while loop for this:

while (the string is not empty)

in combination with a different scanner method...

**JavaN00b** · May 15th, 2011, 06:03 AM

Originally Posted by Norm

Scanner methods are tricky. Some require something be entered and will skip over white space and the Enter key waiting for input.

Try different Scanner methods for reading the input. Perhaps nextLine() will work better.

I won't swear on it but I'm quite sure I went through all of the scanner and string commands yesterday to find something that would work and accept space or enter as input. After hours of trying it didn't work out, I gave up and put it up here for help.....

Anyway,

import java.util.Scanner;
 
public class UserNames {
	public static void main(String[] args0){
		Scanner console = new Scanner(System.in);
 
		String users = "";
		String temp = "";
		System.out.println("Type a person's name (or an empty line to stop): ");
		temp = console.nextLine();
 
		while(!temp.equals("")){
 
			users += temp+" ";
			System.out.println("Type a person's name (or an empty line to stop):");
			temp = console.nextLine();
 
		}
 
		System.out.println("Welcome to all:"+users);
 
	}
 
}

Thanks a lot, using nextLine() did the trick. I don't know what I did wrong yesterday for it not to work. It works perfect now.^^
I'm just surprised that it accepts as "Enter" as imput now when it wouldn't yesterday.

Thanks again for your help people, I shall jump into the depths of coding once again^^

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