CODEWITHSUNDEEP
javareplace
user42155
user42155

Reputation: 49665

How do I replace a character in a string in Java?

Using Java, I want to go through the lines of a text and replace all ampersand symbols (&) with the XML entity reference &.

I scan the lines of the text and then each word in the text with the Scanner class. Then I use the CharacterIterator to iterate over each characters of the word. However, how can I replace the character? First, Strings are immutable objects. Second, I want to replace a character (&) with several characters(amp&;). How should I approach this?

CharacterIterator it = new StringCharacterIterator(token);
for(char ch = it.first(); ch != CharacterIterator.DONE; ch = it.next()) {
       if(ch == '&') {

       }
}

Upvotes: 82

Views: 531185

Answers (11)

dehasi
dehasi

Reputation: 2773

You can use stream and flatMap to map & to &

    String str = "begin&end";
    String newString = str.chars()
        .flatMap(ch -> (ch == '&') ? "&".chars() : IntStream.of(ch))
        .collect(StringBuilder::new, StringBuilder::appendCodePoint, StringBuilder::append)
        .toString();

Upvotes: 3

Atul Anand
Atul Anand

Reputation: 1

String taskLatLng = task.getTask_latlng().replaceAll( "\\(","").replaceAll("\\)","").replaceAll("lat/lng:", "").trim();

Upvotes: -2

Robert Durgin
Robert Durgin

Reputation: 1840

You may also want to check to make sure your not replacing an occurrence that has already been replaced. You can use a regular expression with negative lookahead to do this.

For example: 

String str = "sdasdasa&adas&dasdasa";  
str = str.replaceAll("&(?!amp;)", "&");

This would result in the string "sdasdasa&adas&dasdasa".

The regex pattern "&(?!amp;)" basically says: Match any occurrence of '&' that is not followed by 'amp;'.

Upvotes: 10

Amber
Amber

Reputation: 526593

Try using String.replace() or String.replaceAll() instead.

String my_new_str = my_str.replace("&", "&");

(Both replace all occurrences; replaceAll allows use of regex.)

Upvotes: 141

chamzz.dot
chamzz.dot

Reputation: 775

Try this code.You can replace any character with another given character. Here I tried to replace the letter 'a' with "-" character for the give string "abcdeaa"

OutPut -->_bcdef__

    public class Replace {

    public static void replaceChar(String str,String target){
        String result = str.replaceAll(target, "_");
        System.out.println(result);
    }

    public static void main(String[] args) {
        replaceChar("abcdefaa","a");
    }

}

Upvotes: 1

user2125311
user2125311

Reputation: 67

//I think this will work, you don't have to replace on the even, it's just an example. 

 public void emphasize(String phrase, char ch)
    {
        char phraseArray[] = phrase.toCharArray(); 
        for(int i=0; i< phrase.length(); i++)
        {
            if(i%2==0)// even number
            {
                String value = Character.toString(phraseArray[i]); 
                value = value.replace(value,"*"); 
                phraseArray[i] = value.charAt(0);
            }
        }
    }

Upvotes: 0

Sean Bright
Sean Bright

Reputation: 120644

StringBuilder s = new StringBuilder(token.length());

CharacterIterator it = new StringCharacterIterator(token);
for (char ch = it.first(); ch != CharacterIterator.DONE; ch = it.next()) {
    switch (ch) {
        case '&':
            s.append("&amp;");
            break;
        case '<':
            s.append("&lt;");
            break;
        case '>':
            s.append("&gt;");
            break;
        default:
            s.append(ch);
            break;
    }
}

token = s.toString();

Upvotes: 16

Yishai
Yishai

Reputation: 91881

The simple answer is:

token = token.replace("&", "&amp;");

Despite the name as compared to replaceAll, replace does do a replaceAll, it just doesn't use a regular expression, which seems to be in order here (both from a performance and a good practice perspective - don't use regular expressions by accident as they have special character requirements which you won't be paying attention to).

Sean Bright's answer is probably as good as is worth thinking about from a performance perspective absent some further target requirement on performance and performance testing, if you already know this code is a hot spot for performance, if that is where your question is coming from. It certainly doesn't deserve the downvotes. Just use StringBuilder instead of StringBuffer unless you need the synchronization.

That being said, there is a somewhat deeper potential problem here. Escaping characters is a known problem which lots of libraries out there address. You may want to consider wrapping the data in a CDATA section in the XML, or you may prefer to use an XML library (including the one that comes with the JDK now) to actually generate the XML properly (so that it will handle the encoding).

Apache also has an escaping library as part of Commons Lang.

Upvotes: 93

Chris Vest
Chris Vest

Reputation: 8672

Escaping strings can be tricky - especially if you want to take unicode into account. I suppose XML is one of the simpler formats/languages to escape but still. I would recommend taking a look at the StringEscapeUtils class in Apache Commons Lang, and its handy escapeXml method.

Upvotes: 1

Adamski
Adamski

Reputation: 54705

If you're using Spring you can simply call HtmlUtils.htmlEscape(String input) which will handle the '&' to '&' translation.

Upvotes: 0

Taylor Leese
Taylor Leese

Reputation: 52310

Just create a string that contains all of the data in question and then use String.replaceAll() like below.

String result = yourString.replaceAll("&", "&amp;");

Upvotes: 6

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