What's wrong with using == to compare floats in Java?

Question

According to this java.sun page == is the equality comparison operator for floating point numbers in Java.

However, when I type this code:

Answer 1

Two different calculations which produce equal real numbers do not necessarily produce equal floating point numbers. People who use == to compare the results of calculations usually end up being surprised by this, so the warning helps flag what might otherwise be a subtle and difficult to reproduce bug.