Commons Lang、StandardToStringStyle#setArraySeparator

import org.apache.commons.lang.builder.StandardToStringStyle;

public class C2009072800 {
    public static void main(String[] args) {
        StandardToStringStyle x = new StandardToStringStyle();
        System.out.println(x.getArraySeparator());

        x.setArraySeparator(".");
        System.out.println(x.getArraySeparator());
    }
}

で、

,
.