Question

System.out.println(300 + ((160 - 300) / (240 - 20)) * (27 - 20));
//Should print 295.5 but prints 300

System.out.println(300 + ((160 - 300) / (240 - 20)) * (26 - 20));
//Should print 296.1 but prints 300

I can’t seem to figure out what’s going wrong with this simple equation. I’ve tried storing the variable in ints, doubles, and floats then printing it out, and I still get 300.

I have put the equation into different calculators like Google and http://web2.0calc.com/, and they produce the correct answers.

Please help me.

Answer 1

Cast one of the divide operands to double, and the double type will propagate up through the calculation:

System.out.println(300 + ((160 - 300) / (double)(240 - 20)) * (27 - 20));

Further reading

• Primitive Data Types
• Primitive Types and Values – this is from the Java Language Specification. Dry but perfectly accurate information (very useful). The heart of the matter:

If at least one of the operands to a binary operator is of floating-point type, then the operation is a floating-point operation, even if the other is integral.