What's the right way to parseFloat in Java

Question

I notice some issues with the Java float precision

       Float.parseFloat(\"0.0065\") - 0.001  // 0.0055000000134110451
       new Float(\"0.027\") - 0.001          


        

Answer 1

From the Java Tutorials page on Primitive Data Types:

A floating-point literal is of type float if it ends with the letter F or f; otherwise its type is double and it can optionally end with the letter D or d.

So I think your literals (0.001) are doubles and you're subtracting doubles from floats.

Try this instead:

System.out.println((0.0065F - 0.001D)); // 0.005500000134110451
System.out.println((0.0065F - 0.001F)); // 0.0055

... and you'll get:

0.005500000134110451
0.0055

So add F suffixes to your literals and you should get better results:

Float.parseFloat("0.0065") - 0.001F
new Float("0.027") - 0.001F
Float.valueOf("0.074") - 0.001F