Removing spaces at the end of a string in java

Question

Possible Duplicate:
Strip Leading and Trailing Spaces From Java String

When I import data to an application I need to get rid of the spaces at the end of certain strings but not those at the beginning, so I can't use trim()... I've set up a method:

public static String quitarEspaciosFinal(String cadena) {
    String[] trozos = cadena.split(" ");
    String ultimoTrozo = trozos[trozos.length-1];
    return cadena.substring(0,cadena.lastIndexOf(ultimoTrozo.charAt(ultimoTrozo.length()-1))+1);
    }

where cadena is the string I have to transform...

So, if cadena = " 1234 " this method would return " 1234"...

I'd like to know if there's a more efficient way to do this...

Solution 1

You can use replaceAll() method on the String, with the regex \s+$ :

return cadena.replaceAll("\\s+$", "");

If you only want to remove real spaces (not tabulations nor new lines), replace \\s by a space in the regex.

Solution 2

Apache Commons library has the appropriate method stripEnd.

Solution 3

    String s = "   this has spaces at the beginning and at the end      ";
    String result = s.replaceAll("\\s+$", "");

Solution 4

 public static String replaceAtTheEnd(String input){
    input = input.replaceAll("\\s+$", "");
    return input;
}

Solution 5

I'd do it like this:

public static String trimEnd(String s)
{
    if ( s == null || s.length() == 0 )
        return s;
    int i = s.length();
    while ( i > 0 &&  Character.isWhitespace(s.charAt(i - 1)) )
        i--;
    if ( i == s.length() )
        return s;
    else
        return s.substring(0, i);
}

It's way more verbose than using a regular expression, but it's likely to be more efficient.

View more solutions

Comments

[oopsi]

Is the string just one word, or can it be a sentence?

[m0skit0]

@oopsi: doesn't matter actually ^^

[m0skit0]

I wouldn't use * but +. Useless to replace 0 spaces ;)

[Eugene]

@m0skit0 :) It was first +, then I edit to *, have no idea why :). thx though

[Marko Topolnik]

replaceFirst would serve the purpose here as well.

[m0skit0]

@MarkoTopolnik: replaceFirst()? It's replaceLast() what the OP wants.

[Marko Topolnik]

@m0skit0 That regex can obviously have only a single match. replaceLast is not even a method of String.

[Nicola Musatti]

May I know the reason for the downvote?

[m0skit0]

I wouldn't be so sure about the efficiency thing (regexes might be coded in native code). And it's useless to reinvent the wheel, actually. Why code something manually that you can already do by libraries? You can reinvent the wheel only if what is available doesn't suit you (or is too slow). Optimize later ;) And I actually removed the downvote :P

[m0skit0]

I know it does not exist, it was a joke. Anyway the point is that replaceFirst() is no use here.

[Nicola Musatti]

Obviously the only way to be sure about efficiency is to test against a meaningful data set. That said a regexp is likely to pay for its generality: for instance regexp engines usually translate input expressions for efficiency, which is a step my version doesn't have to perform. As for external libraries I tend to agree with you, but it's still a trade off between maintaining a small piece of code and keep track of yet another dependency. Why, sometimes it just takes less to code and debug something yourself than to look for a ready made solution!

[m0skit0]

But you lose time writing this and testing it. My point is that you don't have to reinvent the wheel if not needed.

[Nactus]

the 2nd link doesn't work anymore