java-unit-formatter

A NumberFormat that selects an appropriate scale and SI unit when formatting.

• Supports both SI prefixes and binary ones.
• Automatically handles the French use of "o" as a symbol for byte.

Sample code

UnitFormat format = UnitFormat.getBytesInstance(Locale.ENGLISH);

assertEquals("25.5 KiB", format.format(25L * 1024L + 512L));
assertEquals("100 MiB", format.format(100L * 1024L * 1024L));
assertEquals("1 KiB", format.format(1024L));

assertEquals("768 B", format.format(768L));
assertEquals("0.8 KiB", format.format(769L));
assertEquals("0.8 MiB", format.format(815L * 1024L));

assertEquals(0L, format.parse("0 B"));

assertEquals(25L * 1024L + 512L, format.parse("25.5 KiB"));
assertEquals(100L * 1024L * 1024L, format.parse("100 MiB"));
assertEquals(1024L, format.parse("1 KiB"));

assertEquals(768L, format.parse("768 B"));
assertEquals(1024.0 * 0.8, format.parse("0.8 KiB"));
assertEquals(1024.0 * 1024.0 * 0.8, format.parse("0.8 MiB"));

format.setNextUnitAt(1536.0);
assertEquals("768 B", format.format(768L));
assertEquals("1,024 B", format.format(1024L));
assertEquals("1,536 B", format.format(1536L));
assertEquals("1.5 KiB", format.format(1537L));

format = UnitFormat.getBytesInstance(Locale.FRENCH);
assertEquals("25,5 Kio", format.format(25L * 1024L + 512L));
assertEquals("1 Kio", format.format(1024L));

assertEquals(25L * 1024L + 512L, format.parse("25,5 Kio"));
assertEquals(1024L, format.parse("1 Kio"));

format = UnitFormat.getSIInstance(Locale.ENGLISH, "m");
format.setMinimumIntegerDigits(1);
format.setMinimumFractionDigits(0);
format.setMaximumFractionDigits(3);

assertEquals("750 m", format.format(750L));
assertEquals("0.751 km", format.format(751L));

assertEquals("100 mm", format.format(0.1));
assertEquals("1 mm", format.format(0.001));
assertEquals("100 µm", format.format(0.0001));
assertEquals("1 µm", format.format(0.000001));

Caveats

• Formatting of the number of units is delegated to a NumberFormat which may use parentheses to format a negative number; there is no way to get the unit inside the parentheses in this case.
• FieldPosition is not supported.
• setParseIntegerOnly is unlikely to work as expected.

Maven

Add a repository to your pom.xml:

<repositories>
  ...
  <repository>
    <id>amjjd-releases</id>
    <url>https://github.com/amjjd/amjjd-mvn-repo/raw/master/releases/</url>
  </repository>
  ...
</repositories>

... and a dependency:

<dependencies>
  ...
  <dependency>
    <groupId>com.amjjd</groupId>
    <artifactId>java-unit-formatter</artifactId>
    <version>0.2</version>
    <scope>compile</scope>
  </dependency>
  ...
</dependencies>

License

Apache 2.0