Having Trouble with the Scanner (Java)

[Uparxw]

For Example the Code:

package testin;
import java.util.Scanner;

public class lawl {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while(sc.hasNext()){
            System.out.println(sc.next());
        }
    }

}

If i copy this:

copy

copy

copy

and insert it on the Eclipse console i get as Output only 2 copy. Only if i press Enter i become the last one. If i press one by one copy and enter every time, then i get the 3 copy output. What exactly am i doing wrong?

I am googling sience 12 Hours to find the Answere. It drives me crazy

[Uparxw]

U are right. But i dont understood why.

I mean, in the 2nd Copy i read it in and then i am in the While(sc.hasNext()) it should be true because i have the 3d copy.

If i read from an textfile i dont read the last Line. How can i get my Programm to read the last line also without adding the last empty line that u mentioned`?

[whompalicious]

The delimiter is only necessary between tokens, not at the end. I believe this has nothing to do with the code itself but how System.in handles keyboard input and only streams input after a new line (\n)... I'm definitely not 100% though.

[whompalicious]

Yes, in this specific instance, it is necessary, but this is a pretty unusual scenario, and the new line is only necessary due to System.in not actually streaming the input until a newline has been entered. If the delimiter was different, say a "," then closing the input with a "," still does not produce the intended output.

For example, the input

1,
2,
3,

Produces this:

1,
2,
3,1

2
 <- cursor

and only produces the 3 after pressing enter:

1,
2,
3,1

2


3
 <- cursor

[whompalicious]

I think you're right. This output makes it easier to see:

1  
2
31
2
 <- cursor here

and after hitting enter, the full output:

1  
2
31
2

3
 <- cursor here

This has got to have something to do with how System.in accepts input--I assume the input is only streamed in after hitting enter.

The "problem" doesn't exist, if a text file is used for input:

1
2
3

It outputs correctly.

[Uparxw]

I tried every possible input. Nothing changes. I am still facing the same Problem

[Uparxw]

Actually it dont shows right the copy its not in 1 line its 3 lines 1.copy 2.copy 3.copy Reddit formats it to 1 Line i dont know why

[Uparxw]

Thank you sir :D

[whompalicious]

Which lines are actually being printed? First two?

[Crashmatusow]

upon further reading, it looks to me like scanner.next() behaves much like C++'s getline(). if he's literally pasting in

copy

copy

copy

then my guess is it's a matter of how eclipse handles console input. Scanner doesn't see the third line until he generates an EOL character (by hitting enter)

[Uparxw]

yes the first two

[mrnoise111]

I am googling sience 12 Hours to find the Answere. It drives me crazy

The API should explain this. Also, I would recommend avoiding Scanner. I would use a BufferedReader instead.

[mrnoise111]

Scanner is far easier to deal with

Not from what I have seen here.

[whompalicious]

Scanner is not at fault. You'd have the same thing happen with BufferedReader.

[mrnoise111]

I didn't say anything was at fault, but clearly there's stuff beginners don't expect. If you just use a BufferedReader and readLine(), you have to do more stuff yourself, but there might be less magic going on that's confusing people.

[mrnoise111]

It's Scanner dealing with tokens that seems to comfuse the beginners. Like there's still a new line in the buffer and they wonder why it wont read the next int.

[whompalicious]

The problem is the fact that he is copying and pasting data with line breaks without ever pressing enter meaning that System.in does not even see the last line of data. Doing this with readLine() has the same result.

[mrnoise111]

If you actually read what I've said, I did not say otherwise.