How to best parameterize a string

Question

For example I have:

String templateString = "Hi {{customerName}}, you have successfully ordered a {{itemName}}."
Map<String, String> parameters = new HashMap<>();
parameters.put("customerName", "Bob");
parameters.put("itemName", "sofa");

Desired output: "Hi Bob, you have successfully ordered a sofa."

What would be the best (foolproof, maintainable, time efficient, etc.) way to get the desired output?

I thought of doing something simple:

String output = templateString;
for (Map.Entry<String, String> entry : parameters.entrySet()) {
    output = output.replace("{{" + entry.getKey() + "}}", entry.getValue());
}

Is there a better way?

*What would be the best (foolproof, maintainable, time efficient, etc.) way to get the desired output?* - [To not reinvent the wheel.](https://stackoverflow.com/questions/2286648/named-placeholders-in-string-formatting) — BackSlash, Sep 17 '18 at 06:56
Nothing wrong at all with your current attempt. What are you looking for here? Note that there are already Java template libraries which can do this. — Tim Biegeleisen, Sep 17 '18 at 06:56
And there is also the built-in solution using [`printf(...)`](https://docs.oracle.com/javase/10/docs/api/java/io/PrintStream.html#printf(java.lang.String,java.lang.Object...)) — Turing85, Sep 17 '18 at 06:58
@Turing85 It doesn't support named parameters, which is what the OP is asking for I guess — BackSlash, Sep 17 '18 at 06:59
to all: First, study the task. Before decrementing of the question. — Valentyn Hruzytskyi, Sep 17 '18 at 07:02
Tim is correct: [Freemarker](https://freemarker.apache.org/) for example does exactly this. Lots of very large companies have used it successfully. — Bohemian, Sep 17 '18 at 07:04

score 1 · Answer 1 · answered Sep 17 '18 at 07:04

1

Depends how sophisticated a templating system you need. There are many out there already.

Two examples are:

answered Sep 17 '18 at 07:04

Stewart

17,616
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score 0 · Answer 2 · answered Sep 17 '18 at 07:26

Another way is to use Mustache.java, docs

String templateString = "Hi {{customerName}}, you have successfully ordered a {{itemName}}.";
Map<String, String> parameters = new HashMap<>();
parameters.put("customerName", "Bob");
parameters.put("itemName", "sofa");

Writer writer = new StringWriter();
MustacheFactory mf = new DefaultMustacheFactory();
Mustache mustache = mf.compile(new StringReader(templateString), "example");
mustache.execute(writer, parameters);
writer.flush();
System.out.println(writer.toString());

score 0 · Answer 3 · answered Sep 17 '18 at 07:27

0

Would be better to fetch values using keys in Map

            String output = templateString;
            output = output.replace("{{customerName}}",parameters.get("customerName"));
            output = output.replace("{{itemName}}",parameters.get("itemName"));

answered Sep 17 '18 at 07:27

chandani jain

9
6

OP is already doing this. The only difference is that he is avoiding hard-coding parameters names instead. – BackSlash Sep 17 '18 at 07:29

Kartik · Answer 4 · 2018-09-17T23:56:00.833

Apart from the solutions already provided in other answers, you can also use StringSubstitutor from Apache Commons Text.

An example from https://commons.apache.org/proper/commons-text/javadocs/api-release/org/apache/commons/text/StringSubstitutor.html :-

 Map valuesMap = HashMap();
 valuesMap.put("animal", "quick brown fox");
 valuesMap.put("target", "lazy dog");
 String templateString = "The ${animal} jumps over the ${target}.";
 StringSubstitutor sub = new StringSubstitutor(valuesMap);
 String resolvedString = sub.replace(templateString);

How to best parameterize a string

4 Answers4