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replaceAll does not replace string [duplicate]

I want the text "REPLACEME" to be replaced with my StringBuffer symbols. When I print symbols, it is a valid string. When I print my query, it still has the text REPLACEME instead of symbols. Why?

private String buildQuery(){
    String query = "http://query.yahooapis.com/v1/public/yql?q=select%20*%20from%20yahoo.finance.quotes%20where%20symbol%20in%20(REPLACEME)&format=json&env=store%3A%2F%2Fdatatables.org%2Falltableswithkeys&callback=";

    deserializeQuotes();

    StringBuffer symbols = new StringBuffer();
    for(int i = 0; i < quotes.size();i++){
        if(i == (quotes.size()-1))
            symbols.append("%22" + quotes.get(i).getSymbol() + "%22%"); //end with a quote
        else
            symbols.append("%22" + quotes.get(i).getSymbol() + "%22%2C");
    }

    System.out.println("***SYMBOLS***" + symbols.toString());
    query.replaceAll("REPLACEME", symbols.toString());

    return query;
}
like image 289
Sheehan Alam Avatar asked Aug 31 '10 17:08

Sheehan Alam


3 Answers

Change

query.replaceAll("REPLACEME", symbols.toString());

to:

query = query.replaceAll("REPLACEME", symbols.toString());

Strings in Java are designed to be immutable.
That is why replaceAll() can't replace the characters in the current string, so it must return a new string with the characters replaced.


Also if you want to simply replace literals and don't need regex syntax support use replace instead of replaceAll (regex syntax support is only difference between these two methods). It is safer in case you would want to replace literals which can contain regex metacharacters like *, +, [, ] and others.

like image 64
Thierry-Dimitri Roy Avatar answered Nov 17 '22 06:11

Thierry-Dimitri Roy


Read the documentation :) replaceAll() returns a new String, it does replace inside the existing String. The reason for that is that Strings are immutable objects.

like image 27
Romain Guy Avatar answered Nov 17 '22 06:11

Romain Guy


The String object in Java is immutable. The replaceAll will not replace the data in the string, it will generate a new string. Try this:

query = query.replaceAll("REPLACEME", symbols.toString());
like image 5
MikeTheReader Avatar answered Nov 17 '22 06:11

MikeTheReader