Commons Lang、BooleanUtils.toStringOnOff()

import org.apache.commons.lang.BooleanUtils;

public class C2009032900 {
    public static void main(String[] args) {
        System.out.println(BooleanUtils.toStringOnOff(true));
        System.out.println(BooleanUtils.toStringOnOff(false));
        System.out.println(BooleanUtils.toStringOnOff(new Boolean(true)));
        System.out.println(BooleanUtils.toStringOnOff(new Boolean(false)));
    }
}

で、

on
off
on
off