Commons Lang、ToStringBuilder#appendToString

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

class C2009062801 {
    int x;

    public String toString() {
        return new ToStringBuilder(this).
            append("x", x).toString();
    }
}

public class C2009062800 extends C2009062801 {
    String str = "foo";

    public String toString() {
        return new ToStringBuilder(this).
            appendToString(super.toString()).
            append("str", str).toString();
    }

    public static void main(String[] args) {
        System.out.println(new C2009062800());
    }
}

で、

C2009062800@1fb8ee3[x=0,str=foo]