String.format
2010-01-13
Already since Java 5.0 (released in Sept. 2004) the String class has been extended by the “format“ class method. This method offers the possibility to use placeholders in a string that will be replaced by argument values. Similar methods are known as “sprinf“ or simply “printf” in various programming languages.
With String.format the following expression
String s = "Hello " + name;
can be re-written as
String s = String.format("Hello %s", name);
It‘s getting more interesting if you want to output formatted values. Here is another example which outputs a number and a formatted date:
String s = "Found " count " requests since " + DateFormat.getDateInstance().format(date);
Now the same expression with the String.format method.
String s = String.format("Found %d requests since %tD", count, date);
Check out the javadocs for more information:
Javadoc: http://java.sun.com/javase/6/docs/api/java/util/Formatter.html#syntax
Javadoc: http://java.sun.com/javase/6/docs/api/java/lang/String.html

Marco Rico Gomez is a passionate software developer located in Germany who likes to share his thoughts and experiences about software development and technologies with others.
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