printf : Java Glossary

printf

Java version 1.5 or later, java.io.PrintWriter. printf, java.io.PrintStream. printf and the java.util. Formatter class give you abilities similar to C’s printf. You can also use String. format to build a String using the formatting scheme. It was added in response to C++ programmers coming to Java who wanted their familiar formatting tools. Don’t confuse printf and print/ println.

It is particularly useful for making listings line up by assigning fixed widths to your fields or for displaying in hex.

G format gives you an ability like the G format in FØRTRAN, which will display in F format or E format as appropriate.

The java.text.DecimalFormat and java.text. NumberFormat classes in Java version 1.1 or later give you similar ability a bit more verbosely. Java 1.0.2 has no equivalent to the C printf or sprintf function for formatting numbers for display. You have to roll your own. One such class is available from San Diego State University called sdsu.FormatString. Acme also has one. Eliote Rusty Harold did one. Gary Cornell and Cay Horstmann’s book Core Java 2 includes one.

Most people don’t bother with printf. They use the + concatenation operator instead of printf.

// in idiomatic Java you would say:
System.out.println( "x:" + x + " y:" + y );

// instead of C-style
System.out.printf( "x: %d y: %d", x, y );

Books

recommend book⇒Core Java Volume I — Fundamentals, ninth edition

by:

Cay S. Horstmann, Gary Cornell

978-0-13-708189-9

paperback

publisher:

Prentice Hall

B004Y521GI

kindle

published:

2012-09-10

Covers Java 1.4 such as regular expressions, New I/O, assertions, Preferences, Swing enhancements and logging. Aimed at someone who already knows C++. This is not a fluffy introductory book.

Greyed out stores probably do not have the item in stock

Learning More

Oracle’s Javadoc on PrintWriter.printf : available:

on the web at Oracle.com
in the current JDK 1.7.0_04 or in the old JDK 1.6.0_32 on your local Windows J: drive.

Oracle’s Javadoc on PrintStream.printf : available:

on the web at Oracle.com
in the current JDK 1.7.0_04 or in the old JDK 1.6.0_32 on your local Windows J: drive.

Oracle’s Javadoc on Formatter class : available:

on the web at Oracle.com
in the current JDK 1.7.0_04 or in the old JDK 1.6.0_32 on your local Windows J: drive.

Oracle’s Javadoc on String.format : available:

on the web at Oracle.com
in the current JDK 1.7.0_04 or in the old JDK 1.6.0_32 on your local Windows J: drive.

DecimalFormat
format
NumberFormat
println format
Sun’s old unofficial sprintf

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