Remove the last chars of the Java String variable

A java String variable whose value is

String path = "http://cdn.gs.com/new/downloads/Q22010MVR_PressRelease.pdf.null"

I want to remove the last four characters i.e., .null. Which method I can use in order to split.

I think you want to remove the last five characters ('.', 'n', 'u', 'l', 'l'):

path = path.substring(0, path.length() - 5);

Note how you need to use the return value - strings are immutable, so substring (and other methods) don't change the existing string - they return a reference to a new string with the appropriate data.

Or to be a bit safer:

if (path.endsWith(".null")) {
  path = path.substring(0, path.length() - 5);
}

However, I would try to tackle the problem higher up. My guess is that you've only got the ".null" because some other code is doing something like this:

path = name + "." + extension;

where extension is null. I would conditionalise that instead, so you never get the bad data in the first place.

(As noted in a question comment, you really should look through the String API. It's one of the most commonly-used classes in Java, so there's no excuse for not being familiar with it.)

import org.apache.commons.lang3.StringUtils;

// path = "http://cdn.gs.com/new/downloads/Q22010MVR_PressRelease.pdf.null"
StringUtils.removeEnd(path, ".null");
// path = "http://cdn.gs.com/new/downloads/Q22010MVR_PressRelease.pdf"

path = path.substring(0, path.length() - 5);

I am surprised to see that all the other answers (as of Sep 8, 2013) either involve counting the number of characters in the substring ".null" or throw a StringIndexOutOfBoundsException if the substring is not found. Or both :(

I suggest the following:

public class Main {

    public static void main(String[] args) {

        String path = "file.txt";
        String extension = ".doc";

        int position = path.lastIndexOf(extension);

        if (position!=-1)
            path = path.substring(0, position);
        else
            System.out.println("Extension: "+extension+" not found");

        System.out.println("Result: "+path);
    }

}

If the substring is not found, nothing happens, as there is nothing to cut off. You won't get the StringIndexOutOfBoundsException. Also, you don't have to count the characters yourself in the substring.

If you like to remove last 5 characters, you can use:

path.substring(0,path.length() - 5)

( could contain off by one error ;) )

If you like to remove some variable string:

path.substring(0,path.lastIndexOf('yoursubstringtoremove));

(could also contain off by one error ;) )

Another way:

if (s.size > 5) s.reverse.substring(5).reverse

BTW, this is Scala code. May need brackets to work in Java.