Get the index of the start of a newline in a Stringbuffer

Question

I need to get the starting position of new line when looping through a StringBuffer. Say I have the following document in a stringbuffer

"This is a test
Test
Testing Testing"

New lines exist after "test", "Test" and "Testing".

I need something like:

for(int i =0;i < StringBuffer.capacity(); i++){
if(StringBuffer.chatAt(i) == '\n')
    System.out.println("New line at " + i);

}

I know that won't work because '\n' isn't a character. Any ideas? :)

Thanks

It doesn't work because capacity() is not the same as length(). Please read documentation! — kan, Oct 04 '11 at 14:30

score 8 · Accepted Answer · answered Oct 04 '11 at 14:35

8

You can simplify your loop as such:

StringBuffer str = new StringBuffer("This is a\ntest, this\n\nis a test\n");

for (int pos = str.indexOf("\n"); pos != -1; pos = str.indexOf("\n", pos + 1)) {
  System.out.println("\\n at " + pos);
}

answered Oct 04 '11 at 14:35

beny23

34,390
5
82
85

score 2 · Answer 2 · answered Oct 04 '11 at 14:28

2

System.out.println("New line at " + stringBuffer.indexOf("\n"));

(no loop necessary anymore)

answered Oct 04 '11 at 14:28

Guillaume

22,694
14
56
70

That will just print the index of the first `'\n'`. What about the others? – Bala R Oct 04 '11 at 14:29
1

Thats what I need. For the others I could have a while loop and it will end when the indexOf is -1 :) – Decrypter Oct 04 '11 at 14:33
@Decrypter, you should have the for loop from beny23, as thats a nice idea. – rapadura Oct 04 '11 at 14:38
Done something similar with a while loop. – Decrypter Oct 04 '11 at 14:45

score 1 · Answer 3 · answered Oct 04 '11 at 14:32

Your code works fine with a couple of syntactical modifications:

public static void main(String[] args) {
    final StringBuffer sb = new StringBuffer("This is a test\nTest\nTesting Testing");

    for (int i = 0; i < sb.length(); i++) {
        if (sb.charAt(i) == '\n')
            System.out.println("New line at " + i);
    }
}

Console output:

New line at 14
New line at 19

Get the index of the start of a newline in a Stringbuffer

3 Answers3