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Message:

Re: Unexpected double value

Posted by Brian Sanders on November 28, 2001 at 1:44 PM

Sun's Java Developer Connection had a goog Tech Tip on this issue. The essence of the problem is this: a double is stored in binary floating-point representation. There is no exact floating-point representation for some numbers (like 0.1), so the real double value is the closest floating-point value to 0.1. In binary, this value is 1001100110011001100110011001100110011001100110011010.

The class java.math.BigDecimal uses a non-floating-point representation for numbers. So, this value:

java.math.BigDecimal oneTenth = new java.math.BigDecimal("0.1");

is exactly equal to 0.1 Use BigDecimal in your program, and you'll get the expected behavior.