Java generating Strings with placeholders

Question

I\'m looking for something to achieve the following:

String s = \"hello {}!\";
s = generate(s, new Object[]{ \"world\" });
assertEquals(s, \"hello world!\");         


        

Answer 1

Justas answer is outdated so I'm posting up to date answer with apache text commons.

StringSubstitutor from Apache Commons Text may be used for string formatting with named placeholders: https://commons.apache.org/proper/commons-text/javadocs/api-release/org/apache/commons/text/StringSubstitutor.html

<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-text</artifactId>
    <version>1.9</version>
</dependency>

This class takes a piece of text and substitutes all the variables within it. The default definition of a variable is ${variableName}. The prefix and suffix can be changed via constructors and set methods. Variable values are typically resolved from a map, but could also be resolved from system properties, or by supplying a custom variable resolver.

Example:

 // Build map
 Map<String, String> valuesMap = new HashMap<>();
 valuesMap.put("animal", "quick brown fox");
 valuesMap.put("target", "lazy dog");
 String templateString = "The ${animal} jumped over the ${target}.";

 // Build StringSubstitutor
 StringSubstitutor sub = new StringSubstitutor(valuesMap);

 // Replace
 String resolvedString = sub.replace(templateString);

Answer 2

This can be done in a single line without the use of library. Please check java.text.MessageFormat class.

Example

String stringWithPlaceHolder = "test String with placeholders {0} {1} {2} {3}";
String formattedStrin = java.text.MessageFormat.format(stringWithPlaceHolder, "place-holder-1", "place-holder-2", "place-holder-3", "place-holder-4");

Output will be

test String with placeholders place-holder-1 place-holder-2 place-holder-3 place-holder-4