Help needed with Scanner

[jishnu dasgupta]

I am trying to run this following code using scanner to obtain the tokens:

import java.util.*;
class TestScanner2
{
	public static void main(String args[])
	{
		System.out.println("Enter search String: ");
		Scanner sc=new Scanner(System.in);
		String token="";
		while(sc.hasNext())
		{
			token=sc.next();
			System.out.println(token);
		}
	}
	
}

However when i am taking the input from the console using the Scanner, the while loop correctly parses the tokens, but then it keeps on looping in endless loop, and the program execution does not stop.

If i change the Scanner object to take the input from command line i.e

Scanner sc=new Scanner(args[0]);

The while loop correctly terminates after parsing out the tokens.

can you please explain why the while loop does not terminate when i am taking input from the user, and is there a way to make the while loop correctly terminate while doing the same

[Luigi Plinge]

System.in is a stream, so Scanner has to wait to see what comes in. If it finished as soon as there was a break in the stream, it wouldn't wait for you to type anything in. So while the stream exists, it assumes there is something else coming. If you just want to wait for 1 token, just remove the while loop and the code should work.

[jishnu dasgupta]

Is there any way that i can place some condition in my while loop, so that after parsing the tokens in my stream the program exists.
say for example, if i enter the input string as: "Hello i am jishnu";

it parses the String and then the program exists.

[Luigi Plinge]

Try Scanner's nextLine() method, which will return the whole line, and use String.split on that.

[Campbell Ritchie]

Luigi Plinge wrote:Try Scanner's nextLine() method, which will return the whole line . . .

Not quite. It returns whatever remains until the next line end. There is lots of potential for confusion about that.

[jishnu dasgupta]

Hi Luigi,

It didnt work with the nextLine()....is there any alternative??

[Luigi Plinge]

Works fine for me -

import java.util.*;
class TestScanner2
{
	public static void main(String args[])
	{
		System.out.println("Enter search String: ");
		Scanner sc=new Scanner(System.in);
//		String token="";
                String line = sc.nextLine();
                String words[] = line.split(" ");
                for(String w : words){
                    System.out.println(w);
                };
	}
	
}

[jishnu dasgupta]

Oh!!...I had that String.split() condition wrong...Thanks anyways!!!...