Java library for fast fixed-point arithmetic based on longs with support for up to 18 decimal places.

http://decimal4j.org/javadoc

• Fixed-point arithmetic with 0 to 18 decimal places
  • Implementation based on unscaled long value
  • Option to throw an exception when an arithmetic overflow occurs
• Scale
  • Type of a variable defines the scale (except for wildcard types)
  • Result has usually the same scale as the primary operand (also for multiplication and division)
• Type Conversion
  • Efficient conversion from and to various other number types
  • Convenience methods to directly inter-operate with other data types (long, double, ...)
  • All rounding modes supported (default: HALF_UP)
• Efficiency
  • Fast and efficient implementation (see performance benchmarks)
  • MutableDecimal implementation for chained operations
  • DecimalArithmetic API for zero-garbage computations (with unscaled long values)

public class Interest {
	public static void main(String[] args) {
		Decimal2f principal = Decimal2f.valueOf(9500);
		Decimal3f rate = Decimal3f.valueOf(0.067);
		Decimal2f time = Decimal2f.valueOf(1).divide(4);
		Decimal2f interest = principal.multiplyBy(rate.multiplyExact(time));
		System.out.println("First quarter interest:  $" + interest);
	}
}

will output

First quarter interest: $159.13

public class Circle {
	public static void main(String[] args) {
		Decimal18f PI = Decimal18f.valueOf(Math.PI);
		Decimal2f radius = Decimal2f.valueOf(5);
		Decimal2f circ = radius.multiplyBy(PI.multiply(2));
		System.out.println("Circumference with 5m radius is ~" + circ + "m");
		System.out.println("Circumference with 5m radius is ~" + (2*Math.PI * 5) + "m");

		Decimal2f down = radius.multiplyBy(PI.multiply(2), RoundingMode.DOWN);
		System.out.println("Circumference with 5m radius is larger than " + down + "m");
	}
}

will output

Circumference with 5m radius is ~31.42m
Circumference with 5m radius is ~31.41592653589793m
Circumference with 5m radius is larger than 31.41m

Can be found in the wiki.

<dependency>
	<groupId>org.decimal4j</groupId>
	<artifactId>decimal4j</artifactId>
	<version>1.0.1</version>
	<scope>compile</scope>
</dependency>

compile 'org.decimal4j:decimal4j:1.0.1'

You can download binaries, sources and javadoc from maven central:

• decimal4j download

• Javadoc API
• Wiki
• [DoubleRounder Utility](https://github.com/tools4j/decimal4j/wiki/DoubleRounder Utility): rounding double values to an arbitrary decimal precision from 0 to 18
• More Examples
• Zero-garbage Computations (with unscaled long values)
• [Test Coverage](https://github.com/tools4j/decimal4j/wiki/Test Coverage)
• Performance Benchmarks