Is there a method in Java that will replace the first occurrence of a String with a given String?

Question

I am trying to write a madlibs program in Java. There is a method that takes a template String, an ArrayList of all the placeholders in that String, and an ArrayList of all the user inputs that will replace those templates, as parameters.

The method looks like this:

private String replacePlaceHolder(String template, ArrayList<String> placeholders, ArrayList<String> replacements){
        for (int i = 0; i < placeholders.size(); i++){
            template = template.replace(placeholders.get(i), replacements.get(i));
        }
        return template;
    }

The problem is, the method is replacing all occurrences of a given template, such as "[Adjective]" with the replacement, instead of just the first one. I tried using template = template.replaceFirst(placeholders.get(i), replacements.get(i)) instead, but it replaced the first placeholder with all of the user inputs, and ignored the rest.

Here is the template I used:

Computer programming, also known as [-ing Verb], is a
process that leads from a [Adjective] problem 
to an executable [Noun]. 
Programming often involves [-ing Verb], 
[-ing Verb], and [-ing Verb], and can be learned
by anyone!
Source code is written in a programming language, 
such as [Animal]code, or Java.
The first ever programmer was [Name of Celebrity], 
who invented [Plural Noun] in the year [Year]. 
Since then, programming has become a 
[Adjective] practice all across the world.

I know that the ArrayList of placeholders matches the placeholders in the template, and that that ArrayList is the same length as the ArrayList of user inputs.

What should I be doing differently?

Answer 1

replaceFirst is the correct answer, but the parameters are regex expressions, so you need to quote the search text, especially since it uses [], which is special regex for a character class.

To quote the values, use Pattern.quote(String s) for the first parameter, and Matcher.quoteReplacement(String s) for the second parameter.

private static String replacePlaceHolder(String template, List<String> placeholders, List<String> replacements) {
    for (int i = 0; i < placeholders.size(); i++){
        template = template.replaceFirst(Pattern.quote(placeholders.get(i)),
                                         Matcher.quoteReplacement(replacements.get(i)));
    }
    return template;
}

Here is a Minimal, Reproducible Example, something you should have provided in the question:

String template = "Computer programming, also known as [-ing Verb], is a\n" +
                  "process that leads from a [Adjective] problem\n" +
                  "to an executable [Noun].\n" +
                  "Programming often involves [-ing Verb],\n" +
                  "[-ing Verb], and [-ing Verb], and can be learned\n" +
                  "by anyone!\n" +
                  "Source code is written in a programming language,\n" +
                  "such as [Animal]code, or Java.\n" +
                  "The first ever programmer was [Name of Celebrity],\n" +
                  "who invented [Plural Noun] in the year [Year].\n" +
                  "Since then, programming has become a\n" +
                  "[Adjective] practice all across the world.";
List<String> placeholders = Arrays.asList(
        "[-ing Verb]", "[Adjective]", "[Noun]",
        "[-ing Verb]", "[-ing Verb]", "[-ing Verb]",
        "[Animal]", "[Name of Celebrity]", "[Plural Noun]",
        "[Year]", "[Adjective]" );
List<String> replacements = Arrays.asList(
        "AA", "BB", "CC",
        "DD", "EE", "FF",
        "GG", "HH", "II",
        "JJ", "KK" );
String result = replacePlaceHolder(template, placeholders, replacements);
System.out.println(result);

Output

Computer programming, also known as AA, is a
process that leads from a BB problem
to an executable CC.
Programming often involves DD,
EE, and FF, and can be learned
by anyone!
Source code is written in a programming language,
such as GGcode, or Java.
The first ever programmer was HH,
who invented II in the year JJ.
Since then, programming has become a
KK practice all across the world.