Attach a D or d to double literals, but it is not necessary. : double « Java Source And Data Type « SCJP

1. SCJP
2. Java Source And Data Type
3. double

public class MainClass{
    public static void main(String[] argv){
        double d = 1.1D; // Optional, not required
        double g = 987.897;       // No 'D' suffix, but OK because the literal is a double by default

        System.out.println(d);
        System.out.println(g);
    }
}