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Belief Driven Design
belief-driven-design.com › looking-at-java-21-string-templates-c7cbc
Looking at Java 21: String Templates | belief driven design
June 20, 2023 - As you can imagine, using format specifiers requires creating a Formatter for the template String. Even though you save on the number of String allocations, now the JVM has to parse/validate the template String. The java.text.MessageFormat type is like the older sibling of String::format, as it uses the same approach of using format String container specifiers.
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Medium
medium.com › @ucgorai › string-templates-in-java-21-simplifying-string-construction-9ba9866ff510
String Templates in Java 21: Simplifying String Construction | by Uma Charan Gorai | Medium
June 19, 2025 - String Templates in Java 21 represent a major step toward more expressive and maintainable Java code. With its preview implementation of FormatProcessor.STR, developers can now write dynamic strings in a safer, cleaner, and more efficient manner.
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Baeldung
baeldung.com › home › java › java string › string templates in java
String Templates in Java | Baeldung
July 7, 2025 - Currently, this is only available if you’re using Java 21 or 22 with preview features enabled. We use Strings to represent sequences of numbers, letters, and symbols as text in code. Strings are ubiquitous in programming, and we often need to compose strings to use in code.
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Nataliia Dziubenko
nataliiadziubenko.com › 2023 › 08 › 18 › so-how-should-we-construct-strings.html
Java 21: So How Should We Construct Strings Now? | Nataliia Dziubenko
August 18, 2023 - I had a preconception that String::format is a better alternative to the + operator. This method can indeed offer improved readability in some cases and supports localization. Some basic benchmarking shows slightly better performance compared to concatenation.
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Oracle
docs.oracle.com › en › java › javase › 21 › docs › api › java.base › java › lang › String.html
String (Java SE 21 & JDK 21)
January 20, 2026 - Unless otherwise noted, passing a null argument to a constructor or method in this class will cause a NullPointerException to be thrown. A String represents a string in the UTF-16 format in which supplementary characters are represented by surrogate pairs (see the section Unicode Character ...
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How to do in Java
howtodoinjava.com › home › java 21 string templates
Java 21 String Templates (with Examples)
July 30, 2024 - String time = STR."The current time is \{ //sample comment - current time in HH:mm:ss DateTimeFormatter .ofPattern("HH:mm:ss") .format(LocalTime.now()) }."; This Java tutorial discusses string templates in Java which is a new addition to the language in Java 21 as a preview feature.
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Oracle
docs.oracle.com › en › java › javase › 21 › docs › › api › java.base › java › util › Formatter.html
Formatter (Java SE 21 & JDK 21)
January 20, 2026 - An interpreter for printf-style format strings. This class provides support for layout justification and alignment, common formats for numeric, string, and date/time data, and locale-specific output. Common Java types such as byte, BigDecimal, and Calendar are supported.
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Medium
medium.com › @kaustubh.saha › string-templates-in-java-21-and-22-46413472c2b3
String Templates in Java 21 and 22 | by Kaustubh Saha | Medium
December 4, 2025 - String.format: Clean separation of text and data, but the arity mismatch (wrong number of arguments) is a runtime error, not a compile-time one. While languages like Python (f-strings) and Kotlin (String interpolation) solved this years ago, Java took its time.
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Medium
medium.com › @ushaushraghunath › more-about-java-21-string-templates-a01e03010835
More about Java 21 String Templates | by Usha SR | Medium
June 11, 2024 - IllegalFormatException if the data type specified in the format(Format Specifier) is not the same as the argument's type or if there are insufficient arguments. With Java 21 there is no need to use String.format method, instead String Templates ...
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Oracle
docs.oracle.com › en › java › javase › 21 › docs › api › › › java.base › java › text › Format.html
Format (Java SE 21 & JDK 21)
January 20, 2026 - Generally, a format's parseObject method must be able to parse any string formatted by its format method. However, there may be exceptional cases where this is not possible. For example, a format method might create two adjacent integer numbers with no separator in between, and in this case the parseObject could not tell which digits belong to which number. The Java Platform provides three specialized subclasses of Format-- DateFormat, MessageFormat, and NumberFormat--for formatting dates, messages, and numbers, respectively.
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Java Knowledge Base
javaknowledgebase.com › home › java tutorial › string template in java 21 – a complete guide
String Template in Java 21 – Modern String Handling
September 10, 2025 - String name = "Ashish"; int age = 30; // Using concatenation String result1 = "My name is " + name + " and I am " + age + " years old."; // Using String.format String result2 = String.format("My name is %s and I am %d years old.", name, age); System.out.println(result1); System.out.println(result2);
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Medium
bohutskyi.com › java-21-string-templates-303ad23106b5
Java 21: String Templates. Java 21 introduces an exciting feature… | by Serhii Bohutskyi | Medium
January 9, 2024 - String name = "Java"; String greeting = STR."Welcome to \{name} 21"; System.out.println(greeting); // Output: Welcome to Java 21 · The embedded expressions within curly braces {} are interpolated at runtime. Additionally, Java's String Templates can process format specifiers, enhancing the way strings are formatted:
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Medium
medium.com › @viraj_63415 › java-21-string-templates-79fd908f30ff
Java String Templates — A Better Interpolation | by Viraj Shetty | Medium
June 19, 2024 - This article talks about a proposed Java 21 JSR 430 — which attempts to rectify this inconvenience. ... Also check out my YouTube Channel at https://www.youtube.com/@viraj_shetty and subscribe for quality software content. Here are some of the ways that Java provides for String construction. All of these methods are relatively difficult to read and are verbose. // String concatenation var l = "My name is " + name + ". My age is " + age + "." // String format method var l = String.format("My name is %s.
Top answer
1 of 12
323

Take a look at String.format. Note, however, that it takes format specifiers similar to those of C's printf family of functions -- for example:

String.format("Hello %s, %d", "world", 42);

…would return "Hello world, 42". The "format string" link points to the complete official spec, but for simple cases, this much shorter documentation may be helpful for an introduction to format specifiers even though it's outdated and about Lava. The most commonly used ones are:

  • %s - insert a string
  • %d - insert a signed integer (decimal)
  • %f - insert a real number, standard notation

This is radically different from C#, which uses positional references with an optional format specifier. That means that you can't do things like:

String.format("The {0} is repeated again: {0}", "word");

... without actually repeating the parameter passed to printf/format. (see The Scrum Meister's comment below)


If you just want to print the result directly, you may find System.out.printf (PrintStream.printf) to your liking.

2 of 12
182

In addition to String.format, also take a look java.text.MessageFormat. The format less terse and a bit closer to the C# example you've provided and you can use it for parsing as well.

For example:

int someNumber = 42;
String someString = "foobar";
Object[] args = {new Long(someNumber), someString};
MessageFormat fmt = new MessageFormat("String is \"{1}\", number is {0}.");
System.out.println(fmt.format(args));

A nicer example takes advantage of the varargs and autoboxing improvements in Java 1.5 and turns the above into a one-liner:

MessageFormat.format("String is \"{1}\", number is {0}.", 42, "foobar");

MessageFormat is a little bit nicer for doing i18nized plurals with the choice modifier. To specify a message that correctly uses the singular form when a variable is 1 and plural otherwise, you can do something like this:

String formatString = "there were {0} {0,choice,0#objects|1#object|1<objects}";
MessageFormat fmt = new MessageFormat(formatString);
fmt.format(new Object[] { new Long(numberOfObjects) });
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Java Code Geeks
examples.javacodegeeks.com › home › java development › core java
Guide to String Templates in Java 21 - Java Code Geeks
March 6, 2024 - Fig 1.0 Output of using STR Template processor with multiline expressions – java 21 string templates · FMT Template processor is similar to STR, but allows using format specifiers like printf for finer control over formatting.
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Medium
medium.com › @mandeepdhakal11 › string-manipulation-in-java-21-9ae6575c92a1
String Manipulation in Java 21. The latest Java version introduced… | by Mandeep Dhakal | Medium
October 9, 2023 - FormatProcessor THAI = FormatProcessor.create(Locale.forLanguageTag("th-TH-u-nu-thai")); for (int i = 1; i <= 5; i++) { String thai = THAI."This answer is ]\{i}"; System.out.println(thai); } // This answer is ๑ // This answer is ๒ // This answer is ๓ // This answer is ๔ // This answer is ๕ ... In this blog, we have seen String Template examples and usage which is a preview feature in Java 21.
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OpenJDK
cr.openjdk.org › ~jlaskey › templates › docs › api › java.base › java › util › Formatter.html
Formatter (Java SE 21 & JDK 21 [ad-hoc build])
An interpreter for printf-style format strings. This class provides support for layout justification and alignment, common formats for numeric, string, and date/time data, and locale-specific output. Common Java types such as byte, BigDecimal, and Calendar are supported.
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nipafx
nipafx.dev › inside-java-newscast-71
What Happened to Java's String Templates? Inside Java Newscast #71 // nipafx
Then let's dive right in! JDK 21 and 22 previewed string templates, a language feature that makes it easier to safely embed variables in structured languages like SQL, HTML, JSON, etc.
Published: June 20, 2024
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At15
at15.dev › string templates
Java 21 String Templates | at15 blog
import static java.lang.StringTemplate.STR; class Main { public static void main(String[] args) { var name = "World"; System.out.println(STR."Hello, \{name}!"); System.out.println(STR.""" Hello! This is a new \{name}! """); } } https://docs.oracle.com/en/java/javase/21/language/string-templates.html#GUID-78F545D3-CDD0-415C-9B4B-6EF361D184F5
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javaspring
javaspring.net › blog › java-21-string-templates
Java 21 String Templates: A Comprehensive Guide — javaspring.net
String Templates offer a more powerful and expressive way to create strings compared to traditional string concatenation and `String.format()` methods. This blog post will delve into the fundamental concepts, usage methods, common practices, and best practices of Java 21 String Templates.