Here is an example of how to use the DoubleBitsFromCharArray class from the Apache Commons IO library to convert a char array to a double:

import org.apache.commons.io.EndianUtils;

char[] charArray = {'3', '.', '1', '4', '1', '5', '9', '2', '6', '5', '3', '8', '9', '7', '9', '3'};
double convertedDouble = EndianUtils.readSwappedDouble(charArray, 0);
System.out.println(convertedDouble);

This code imports the EndianUtils class from the Apache Commons IO library, which contains the DoubleBitsFromCharArray class. It then creates a char array with the characters representing a double value (3.141592653897), and uses the readSwappedDouble method to convert it to a double. The result is printed as 3.141592653897.

This class is used when you want to convert the char array to double with considering the endianness of the system.