strange outcome!

[consurgens]

public class Test {
public static void main(String[] args) {
double n = 20.5 - 20.37;

System.out.println("n = " + n);
}
}

With this code the outcome should be n = 0.13 but instead, it displays 0.129999999999999

I don't know what wrong with this code.
Could anyone explain me what happen?

Thank you ^^

[PhHein]

What Every Computer Scientist Should Know About Floating-Point Arithmetic
Floating Point : Java Glossary

[consurgens]

Thank you for reply

I've just studied programming language and I have chosen Java as primary language. So I don't know much about programming. Could you show me coding that make this outcome as 0.13?

Thank you.

[PhHein]

Have a look at the DecimalFormat API.

[consurgens]

import java.text.*;

public class Test {
public static void main(String[] args) {

DecimalFormat df = new DecimalFormat("0.00");
double n = 20.5 - 20.37;

System.out.println(df.format(n));
}
}

[consurgens]

Thank for your recommendation

^^

[PhHein]

You're welcome.