In Java, when I supply a floating point variable to printf or String.format ,

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Asked: June 11, 20262026-06-11T23:48:12+00:00 2026-06-11T23:48:12+00:00

In Java, when I supply a floating point variable to printf or String.format ,

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In Java, when I supply a floating point variable to printf or String.format, it gives nothing. To illustrate, an example:

public class test {
    public static void main(String arg[]) {
        double d = 123.456; 
        System.out.println("println: " + d + " " + (int) d);
        System.out.printf("printf as int: %d%n", (int) d);
        System.out.printf("printf with %%f: %f%n", d);
        System.out.printf("printf with %%e: %e%n", d);
        System.out.printf("printf with %%g: %g%n", d);
        System.out.printf("printf with %%a: %a%n", d);
    }
}

gives

in println: 123.456 123
in printf as int: 123
in printf with %f: 
in printf with %e: 
in printf with %g: 
in printf with %a:

as You can see, it does work with println, but it fails on printf. Same goes with String.format. If I supply width and precision, it does the same – gives nothing.

What am I doing wrong?

EDIT:
I am using en_US.UTF-8 locale;
I am not sure what version of Java I am using. What I know is: I compile it with gcc (gcj), version 4.7.2; And Have gcj JRE version 4.7.2 and OpenJDK JRE version 7u7-2.3.2a installed.;
Edited the code. Now it is the whole code of the program. I wrote it as a small test program after I noticed these problems with floating point numbers in my other code.