Question

Given below the test code and its output. When I get float value from number value, precision is lost.. Can anyone tell me why this behaviour and also how to handle this?

public static void main(String[] args)
    {
        try
        {
            java.lang.Number numberVal = 676543.21;
            float floatVal = numberVal.floatValue();
            System.out.println("Number value    : " + numberVal);
            System.out.println("float value     : " + floatVal);
            System.out.println("Float.MAX_VALUE : " + Float.MAX_VALUE);
            System.out.println("Is floatVal > Float.MAX_VALUE ? " + ( floatVal > Float.MAX_VALUE));
        }catch(Exception e)
        {
            e.printStackTrace();
        }
    }

output:

    Number value    : 676543.21
    float value     : 676543.2
    Float.MAX_VALUE : 3.4028235E38
    Is floatVal > Float.MAX_VALUE ? false

also why the float value lesser than Float.MAX_VALUE?

Answer 1

I love these. But I’ll make it quick and painless.

Floats and decimals (aka floating points) aren’t kept in the memory precisely either. But I don’t want to get into float accuracy vs precision issues here, i’ll just point you to a link – http://www.cygnus-software.com/papers/comparingfloats/comparingfloats.htm

As far as your other question, lemme put it this way, since floats are stored in scientific notation.

floatVal = 6.765432E6 = 6.7 * 10^6
MAX_VALUE = 3.4E38 = 3.4 * 10^38

MAX_VALUE is 32 orders of magnitude bigger than your float number. Feel free to take a look at here as well http://steve.hollasch.net/cgindex/coding/ieeefloat.html

I’ve spent a great deal of time comparing and fixing some FP issues a few months ago…

Try to use a small delta when comparing floats.
Maybe this link will help you http://introcs.cs.princeton.edu/java/91float/