How do I delete specific characters from a particular String in Java?

Question

For example I'm extracting a text String from a text file and I need those words to form an array. However, when I do all that some words end with comma (,) or a full stop (.) or even have brackets attached to them (which is all perfectly normal).

What I want to do is to get rid of those characters. I've been trying to do that using those predefined String methods in Java but I just can't get around it.

score 181 · Answer 1 · answered Dec 25 '09 at 23:15

181

Reassign the variable to a substring:

s = s.substring(0, s.length() - 1)

Also an alternative way of solving your problem: you might also want to consider using a StringTokenizer to read the file and set the delimiters to be the characters you don't want to be part of words.

answered Dec 25 '09 at 23:15

Mark Byers

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that's exactly what I did and it worked :) BTW I forgot to mention that the use of StringTokenizer class was strictly forbidden by my mentor. – Slavisa Perisic Dec 25 '09 at 23:27
This micro-benchmark suggests that substring() may be faster than regex in this context: http://groups.google.com/group/comp.lang.java.programmer/msg/cf4e57a09eb8ff7c – trashgod Dec 25 '09 at 23:45
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@trashgod - you don't need a microbenchmark to tell you that. Just a tiny amount of common sense ... and looking at the source code of `String.substring()`. – Stephen C Dec 26 '09 at 01:12

score 17 · Accepted Answer · edited Oct 22 '16 at 14:12

17

Use:

String str = "whatever";
str = str.replaceAll("[,.]", "");

replaceAll takes a regular expression. This:

[,.]

...looks for each comma and/or period.

edited Oct 22 '16 at 14:12

Pshemo

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answered Dec 25 '09 at 23:17

OMG Ponies

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thank you :) I knew it wasn't something difficult, just couldn't get around it. – Slavisa Perisic Dec 25 '09 at 23:23
Too many characters in charter literal. How do I actually type this? – Oliver Dixon Apr 29 '15 at 20:42

score 7 · Answer 3 · edited May 23 '17 at 11:48

7

To remove the last character do as Mark Byers said

s = s.substring(0, s.length() - 1);

Additionally, another way to remove the characters you don't want would be to use the .replace(oldCharacter, newCharacter) method.

as in:

s = s.replace(",","");

and

s = s.replace(".","");

edited May 23 '17 at 11:48

Community

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answered Dec 25 '09 at 23:22

Tom Neyland

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score 4 · Answer 4 · answered Dec 25 '09 at 23:10

4

You can't modify a String in Java. They are immutable. All you can do is create a new string that is substring of the old string, minus the last character.

In some cases a StringBuffer might help you instead.

answered Dec 25 '09 at 23:10

bmargulies

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Thank you. I managed to do something like this: [code] for (int i = 0; i < textArray.length; i++) { if ((textArray[i].endsWith(",")) || textArray[i].endsWith(".")) textArray[i].substring(textArray[i].indexOf(textArray[i].length()-1)); System.out.println(textArray[i].toLowerCase()); } [/code] – Slavisa Perisic Dec 25 '09 at 23:25

AlexGach · Answer 5 · 2013-09-20T19:19:39.550

3

The best method is what Mark Byers explains:

s = s.substring(0, s.length() - 1)

For example, if we want to replace \ to space " " with ReplaceAll, it doesn't work fine

String.replaceAll("\\", "");

or

String.replaceAll("\\$", "");   //if it is a path

edited Sep 20 '13 at 19:19

answered Jun 26 '12 at 16:37

AlexGach

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I don't think it's a bad answer, but one thing it's not is INFALLLIBLE. Try it on "" – Bill K May 28 '13 at 20:43

score 0 · Answer 6 · answered Dec 25 '09 at 23:21

Note that the word boundaries also depend on the Locale. I think the best way to do it using standard java.text.BreakIterator. Here is an example from the java.sun.com tutorial.

import java.text.BreakIterator;
import java.util.Locale;

public static void main(String[] args) {
    String text = "\n" +
            "\n" +
            "For example I'm extracting a text String from a text file and I need those words to form an array. However, when I do all that some words end with comma (,) or a full stop (.) or even have brackets attached to them (which is all perfectly normal).\n" +
            "\n" +
            "What I want to do is to get rid of those characters. I've been trying to do that using those predefined String methods in Java but I just can't get around it.\n" +
            "\n" +
            "Every help appreciated. Thanx";
    BreakIterator wordIterator = BreakIterator.getWordInstance(Locale.getDefault());
    extractWords(text, wordIterator);
}

static void extractWords(String target, BreakIterator wordIterator) {
    wordIterator.setText(target);
    int start = wordIterator.first();
    int end = wordIterator.next();

    while (end != BreakIterator.DONE) {
        String word = target.substring(start, end);
        if (Character.isLetterOrDigit(word.charAt(0))) {
            System.out.println(word);
        }
        start = end;
        end = wordIterator.next();
    }
}

Source: http://java.sun.com/docs/books/tutorial/i18n/text/word.html

score 0 · Answer 7 · answered Dec 25 '09 at 23:22

0

You can use replaceAll() method :

String.replaceAll(",", "");
String.replaceAll("\\.", "");
String.replaceAll("\\(", "");

etc..

answered Dec 25 '09 at 23:22

fastcodejava

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replaceAll will replace all the character not the last character only. – chinna_82 Apr 24 '14 at 04:37

How do I delete specific characters from a particular String in Java?

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