Programming Forums > Application Development > Java

thenewkid · Sep 7th, 2005, 11:05 PM

hey....i was studying the topic of exceptions in java and how to use them..i have written this little program just to touch the problem from the practical side...however there is some issue with the label I've used...at compile time it gives me: undefined label: read_in...can u check the code out and tell me whats wrong with it...thanks in advance

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import java.io.*;

public class etest
{
	public static void main(String[] args)
		throws java.io.IOException, NotALetter	
	{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

	read_in:

		System.out.print("Enter word: ");
		String str = br.readLine();	
		try	
		{
			for(int i = 0; i < str.length(); i++)
				if(Character.isLetter(str.charAt(i)) == false)
					throw new NotALetter("no nums");
		}
		catch (NotALetter e)
		{
			break read_in;
		}

	}
}

class NotALetter extends IOException
{
	public NotALetter() {}
	public NotALetter(String str)
	{
		super(str);
	}
}

Polyphemus_ · Sep 8th, 2005, 1:52 AM

Java doesn't support labels, IIRC. But why use them? You can just give an error message or just ignore the whole error, like:

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catch (NotALetter e) {

}

When an error is thrown, it will automatically skip everything what is left in the try block.

Sep 7th, 2005, 11:05 PM	#1
thenewkid Programmer Join Date: Sep 2004 Location: New Jersey Posts: 36 Rep Power: 0	quick question about java labels hey....i was studying the topic of exceptions in java and how to use them..i have written this little program just to touch the problem from the practical side...however there is some issue with the label I've used...at compile time it gives me: undefined label: read_in...can u check the code out and tell me whats wrong with it...thanks in advance (Toggle Plain Text) import java.io.; public class etest { public static void main(String[] args) throws java.io.IOException, NotALetter { BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); read_in: System.out.print("Enter word: "); String str = br.readLine(); try { for(int i = 0; i < str.length(); i++) if(Character.isLetter(str.charAt(i)) == false) throw new NotALetter("no nums"); } catch (NotALetter e) { break read_in; } } } class NotALetter extends IOException { public NotALetter() {} public NotALetter(String str) { super(str); } } import java.io.; public class etest { public static void main(String[] args) throws java.io.IOException, NotALetter { BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); read_in: System.out.print("Enter word: "); String str = br.readLine(); try { for(int i = 0; i < str.length(); i++) if(Character.isLetter(str.charAt(i)) == false) throw new NotALetter("no nums"); } catch (NotALetter e) { break read_in; } } } class NotALetter extends IOException { public NotALetter() {} public NotALetter(String str) { super(str); } }

Sep 8th, 2005, 1:52 AM	#2
Polyphemus_ Expert Programmer Join Date: Aug 2005 Location: Rotterdam, the Netherlands Posts: 942 Rep Power: 4	Java doesn't support labels, IIRC. But why use them? You can just give an error message or just ignore the whole error, like: (Toggle Plain Text) catch (NotALetter e) { } catch (NotALetter e) { } When an error is thrown, it will automatically skip everything what is left in the try block.

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Programming Forums > Application Development > Java

quick question about java labels