Stdin reading multiple lines

Question

I have the following code:

        BufferedReader stdin = new BufferedReader(new InputStreamReader(System.in));
        String submittedString = "";
        System.out.flush();
        submittedString = stdin.readLine();

        int numberofLines = Integer.parseInt(submittedString.split(" ")[0]);

        for(int i = 0; i < numberofLines; i++)
            submittedString += stdin.readLine();

        zipfpuzzle mySolver = new zipfpuzzle();
        mySolver.getTopSongs(submittedString);

However, despite the input being over multiple lines, this only reads the first.

Where is my mistake?

If it makes any difference, I am compiling on eclipse.

Cheers! Dario

It reads all user inputs separately, but you concatenate them and see them as one string!!! — Juvanis, Apr 01 '13 at 16:16
See http://stackoverflow.com/questions/207947/java-how-do-i-get-a-platform-independent-new-line-character on how to have platform-independent end-of-line codes. — PM 77-1, Apr 01 '13 at 16:21
Can you provide a sample of the data you're passing to this? — ahjmorton, Apr 01 '13 at 16:22
ok multiline comments are not allowd, but it should be 4 2 (newline) 30 one (newline) etc — MrD, Apr 01 '13 at 16:23

Juvanis · Answer 1 · 2013-04-01T16:24:20.553

4

Just use an array and populate it within your for-loop:

String[] inputs = new String[numberofLines];

for (int i = 0; i < numberofLines; i++)
    inputs[i] = stdin.readLine();

Extra Note:

If you want multiple lines with single String:

String submittedString = "";

for (int i = 0; i < numberofLines; i++)
    submittedString += stdin.readLine() + System.getProperty("line.separator");

edited Apr 01 '13 at 16:24

answered Apr 01 '13 at 16:19

Juvanis

25,802
5
69
87

But is it possible to have multi-line strings in Java? – MrD Apr 01 '13 at 16:22
@DarioPanada yes. see my extra note. denote the newline! – Juvanis Apr 01 '13 at 16:24
`"\n"` can look weird in various Windows text editors. Consider using the `System.getProperty("line.separator");` as suggested by @PM77-1 in the question comments. – jedwards Apr 01 '13 at 16:27
@jedwards yes, definitely. that way is better. – Juvanis Apr 01 '13 at 16:29

score 3 · Answer 2 · answered Apr 01 '13 at 16:18

3

BufferedReader stdin = new BufferedReader(new InputStreamReader(System.in));
String line = "";

while ((line = stdin.readLine()) != null){
// Do something.
submittedString += line + '\n';

}

answered Apr 01 '13 at 16:18

Achintya Jha

12,735
2
27
39

Tried this, but it will keep reading lines even one one is null – MrD Apr 01 '13 at 16:20

score -1 · Answer 3 · answered Apr 01 '13 at 16:19

-1

submittedString = stdin.readLine();

BufferedReaders readLine method will read System.in until it hits a new line, therefore if you're using the first line of the file to determine the number of lines to read then your data must be incorrect.

answered Apr 01 '13 at 16:19

ahjmorton

965
1
5
18

Stdin reading multiple lines

3 Answers3