Numbers - Java - page 205

}

}

Handling Very Large Numbers

Problem

You need to handle integer numbers larger than Long.MAX_VALUE or floating-point values
larger than Double.MAX_VALUE .

Solution

Use the BigInteger or BigDecimal values in package java.math , as shown in
Example 5-7 .

Example 5-7. BigNums.java
System . out . println ( "Here's Long.MAX_VALUE: " + Long . MAX_VALUE );
BigInteger bInt = new

new BigInteger ( "3419229223372036854775807" );
System . out . println ( "Here's a bigger number: " + bInt );
System . out . println ( "Here it is as a double: " + bInt . doubleValue ());

Note that the constructor takes the number as a string. Obviously you couldn't just type the
numeric digits because, by definition, these classes are designed to represent numbers larger
than will fit in a Java long .

Discussion

Both BigInteger and BigDecimal objects are immutable; that is, once constructed, they al-
ways represent a given number. That said, a number of methods return new objects that are
mutations of the original, such as negate() , which returns the negative of the given BigIn-
teger or BigDecimal . There are also methods corresponding to most of the Java language
built-in operators defined on the base types int / long and float / double . The division meth-
od makes you specify the rounding method; consult a book on numerical analysis for details.
Example 5-8 is a simple stack-based calculator using BigDecimal as its numeric data type.

Example 5-8. BigNumCalc
public public class class BigNumCalc BigNumCalc {