BigDecimal in Java: everything you need to know about the class

With the Java BigDecimal class, it is possible to process complex floating point numbers precisely. These must first be created, and can then be used by various methods. In doing so, the syntax used is always structured in a similar way, so that beginners can use this class after a short learning period.

What is Java BigDecimal?

Java BigDecimal is a class that allows you to represent and manipulate complex floating point numbers of any size in theory with high precision. Using various methods that we present to you in this article, you can perform rounding, arithmetic, format conversion, hashing, and advanced comparison operations of the highest precision with this class.

Java BigDecimal consists of a 32-bit integer scale and a unscaled integer value (unscale in English) of any precision. In this case, « scale » refers to the number of digits after the decimal point, if it is greater than or equal to zero. If the value is less than zero, however, it is multiplied by « 10^(-scale) ». The possible size of the class is limited only by the computer's memory. This aspect remains rather theoretical because it is unlikely that a program will create a number that exceeds the available memory. While BigDecimal in Java is intended exclusively for floating point numbers, integers are handled with the BigInteger class.

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What is the class for?

Due to its precision, Java BigDecimal is not required for every application, but there are situations and application areas where the class is indispensable. Calculations where even the smallest decimal can have a significant effect occur, for example, in the field of e-commerce for transactions. The class is also used for precise static analyses. Many programs, which are used for example for the the control and navigation of aircraft or missilesrely on this class. Java BigDecimal is also used in the medical domain. In other sectors, this precise calculation offers the greatest possible certainty.

If you want to use Java BigDecimal, you must first import the class into the Java program. Once this is done, you can then declare an object of this classthen create the desired value as an argument and pass it to the appropriate Java constructor. Once this is done, you can use the BigDecimals created in Java. There are several methods available within the class, the usage of which we detail in the following sections. Here's how to import the class first and then declare two example objects:

/ / Votre programme Java pour la classe BigDecimal
import java.math.BigDecimal;
public class BigDecimalExemple
{
	public static void main(String[] args)
	{
		/ / Créer deux nouveaux BigDecimal
		BigDecimal ExempleUn =
			new BigDecimal ("1275936001.744297361");
		BigDecimal ExempleDeux =
			new BigDecimal ("4746691047.132719503");
	}
}

You can now use these objects with the corresponding methods of the class.

Examples for Java BigDecimal

After creating the objects, you use different methods to perform operations and use the objects in this way. We will show you with some simple examples how this works and what results you can get. The output is initiated by the Java command System.out.println().

Add two BigDecimals

If you want to add two BigDecimals in Java, you can use the method add(). To do this, you fill in the two values ​​whose sum you want to calculate. In our example, we want to add the value « ExampleOne » to the value « ExampleTwo ». The code looks like this:

ExempleUn =
ExempleUn.add(ExempleDeux);
System.out.println ("Le résultat recherché après l’addition est : " + ExempleUn);

Subtract numbers

To subtract two values ​​you need the method subtract(). The following example involves subtracting « ExampleTwo » from « ExampleOne ». The corresponding code looks like this:

ExempleUn =
ExempleUn.subtract(ExempleDeux);
System.out.println ("Le résultat recherché après la soustraction est : " + ExempleUn);

Multiply the values

The method by which you multiply two BigDecimals in Java works very similarly. It is multiply() and uses the « multiply » object as an argument. If you want to multiply « ExampleTwo » by « ExampleOne », the corresponding code looks like this:

ExempleUn =
ExempleUn.multiply(ExempleDeux);
System.out.println ("Le résultat recherché après la multiplication est : " + ExempleUn);

Dividing numbers

If you want to divide two BigDecimals in Java, go for the method divide(). In principle, it also adopts the known syntax and looks like this:

ExempleUn =
ExempleUn.divide(ExempleDeux);
System.out.println ("Le résultat recherché après la division est : " + ExempleUn);

This only works, however, if the result is exact or an integer. If this is not the case, the following error message is issued: java.lang.ArithmeticException: Non-terminating decimal expansion; no exact representable decimal result.. This describes a runtime error. To avoid this, there are different rounding options for the divide() method, which can be passed via java.math.RoundingMode. You can choose from the following constants:

Overview of the most important methods

Now that you have learned how to use Java BigDecimal and call methods for this purpose, we will conclude by presenting some of the most important methods in an overview.