How to format strings in Java

Question

Primitive question, but how do I format strings like this:

"Step {1} of {2}"

by substituting variables using Java? In C# it's easy.

Answer 1

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". You may find this helpful when learning about the format specifiers. Andy Thomas-Cramer was kind enough to leave this link in a comment below, which appears to point to the official spec. 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)

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