Java BigInteger doubleValue() method example

java.math.BigInteger doubleValue()

Description

On this document we will be showing a java example on how to use the doubleValue() method of BigInteger Class. Basically this method converts this BigInteger to a double. This conversion is similar to the narrowing primitive conversion from double to float as defined in section 5.1.3 of The Java™ Language Specification: if this BigInteger has too great a magnitude to represent as a double, it will be converted to Double.NEGATIVE_INFINITY or Double.POSITIVE_INFINITY as appropriate. Since the BigInteger can hold higher precision, when we do conversion to double value at some point we will lose some precision.

For reference the byte range is from 4.9E-324 to 1.7976931348623157E308 and these information is readily available through the Double constants Double.MIN_VALUE and Double.MAX_VALUE.

Method Syntax

public double doubleValue()

Method Argument

Data Type	Parameter	Description
N/A	N/A	N/A

Method Returns

The doubleValue() method returns this BigInteger converted to a double.

Compatibility

Requires Java 1.1 and up

Java BigInteger doubleValue() Example

Below is a java code demonstrates the use of doubleValue() method of BigInteger class. The example presented might be simple however it shows the behavior of the doubleValue() method.

package com.javatutorialhq.java.examples;

import java.math.BigInteger;
import java.util.Scanner;

/*
 * A java example source code to demonstrate
 * the use of doubleValue() method of BigInteger class
 */

public class BigIntegerDoubleValueExample {

	public static void main(String[] args) {	
		
		// Declare and initialize our BigInteger values
		BigInteger val1 = new BigInteger("12");
		BigInteger val2 = new BigInteger("56554564564564578");

		
		// get the double value of each BigInteger
		double doubleVal1 = val1.doubleValue();
		double doubleVal2 = val2.doubleValue();
		
		// print the operation
		System.out.println("val1 in double is "+doubleVal1);
		System.out.println("val2 in double is "+doubleVal2);		
		
	}

}

This example is a lot simpler than it looks. We only initialize two BigInteger values, one that we know is in range of double and the other is outside the range. The result of the doubleValue is printed out.

Sample Output

Below is the sample output when you run the above example.

References

Oracle Java Documentation