Question

What classes do you use to make string placeholders work?

 String template = "You have %1 tickets for %d",
 Brr object = new Brr(template, {new Integer(1), new Date()});
 object.print();

Answer 1

You have two options:

• java.util.Formatter
  • 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.
• java.text.MessageFormat.
  • MessageFormat provides a means to produce concatenated messages in a language-neutral way. Use this to construct messages displayed for end users.

Of the two, MessageFormat is by far the more powerful. Here’s an example of using ChoiceFormat to handle 0, 1, and >1 case differently:

import java.text.MessageFormat;
import java.util.Date;
//...

String p = "You have {0,choice,0#none|1#one ticket|1<{0,number,integer} tickets} for {1,date,full}.";
for (int i = 0; i < 4; i++) {
    System.out.println(MessageFormat.format(p, i, new Date()));
}

This prints:

You have none for Tuesday, June 1, 2010.
You have one ticket for Tuesday, June 1, 2010.
You have 2 tickets for Tuesday, June 1, 2010.
You have 3 tickets for Tuesday, June 1, 2010.

The documentation has many more examples.