StringBuffer Question

[Rob Levo]

I need to delete all characters in a StringBuffer from the beginning through the first occurance of a newline character. Essentially, I am deleting the first line.
I am aware of the delete method that takes the start and end, but I do not know how to determine the end index, or the first occurrance of the newline. There does not seem to be a method to find the index of a particular character, but I know this should to be an easy thing to accomplish.
Can someone show me the code that will do this delete.
Thanks in advance for the help,
Rob

[Vikas Varma]

Hi Rob,
This may not be the optimal code, but this code works!

 StringBuffer strbuf = new StringBuffer();
        strbuf.append("First Line\nSecond Line");
        System.out.println(strbuf);
        int strind = strbuf.toString().indexOf('\n');
        if (strind != -1) {
            strbuf.delete(0, strind);
        }
        System.out.println(strbuf);
 

[Rob Levo]

Originally posted by Vikas Varma:
Hi Rob,
This may not be the optimal code, but this code works!

 StringBuffer strbuf = new StringBuffer();
        strbuf.append("First Line\nSecond Line");
        System.out.println(strbuf);
        int strind = strbuf.toString().indexOf('\n');
        if (strind != -1) {
            strbuf.delete(0, strind);
        }
        System.out.println(strbuf);
 

Thanks!!
Does anyone know of a way to do it without converting toString, I think that is where it might slow, this StringBuffer could be quite large.

[Neil Laurance]

Another method to consider:

import java.io.*;
public class RemoveFirstLine {
  public static void main(String[] args) {
    BufferedReader br = new BufferedReader(
        new StringReader("Test\nThis"));
    String line = null;
    // discard first line
    try {
      br.readLine();
    } catch(IOException e) {}
    // now print remainder
    try {
      while((line = br.readLine()) != null) {
        System.out.println(line);
      }
    } catch(IOException e) {}
  }
}

Don't know if its any more efficient. Cheers, Neil
(And my example doesn't actually use a StringBuffer at all . Perhaps you need to consider if you need a StringBuffer at all)
[ October 03, 2002: Message edited by: Neil Laurance ]

[Neil Laurance]

Umm, and an example using StringBuffer:

public class RemoveFirstLineSB {
  public static void main(String[] args) {
    StringBuffer sb = new StringBuffer("Test\nThis");
    while(sb.charAt(0) != '\n') {
      sb.deleteCharAt(0);
    }
    // now remove '\n'
    sb.deleteCharAt(0);
    System.out.println(sb);
  }
}

Cheers, Neil

[Rob Levo]

Thanks.
It just seems like there should be something analogous to indexOf for StringBuffer, but I guess not for some reason.

[Rob Levo]

Originally posted by Neil Laurance:
Umm, and an example using StringBuffer:

public class RemoveFirstLineSB {
  public static void main(String[] args) {
    StringBuffer sb = new StringBuffer("Test\nThis");
    while(sb.charAt(0) != '\n') {
      sb.deleteCharAt(0);
    }
    // now remove '\n'
    sb.deleteCharAt(0);
    System.out.println(sb);
  }
}

Cheers, Neil

Neil,
Perfect!!!
Thanks,
Rob