how to get rid of outer-class reference in xstream output?

Question

I use xstream to marshal an object with nested class to xml string, I write this:

public static String java2xml(Object obj, Class<?> T) {

    XStream xstream = new XStream(new StaxDriver());
    xstream.processAnnotations(T);
    String xml = xstream.toXML(obj);

    return xml;
}   

Yet I got a <outer-class reference="../.."/> inside the output string.

the object class is:

public class Foo {
    private String foocontent;
    private Bar bar;

    // getter and setter


    public class Bar {
        private String blabla;
        // getter and setter
    }

}

and I make a Foo with this code:

    Foo foo = new Foo();
    Bar bar = foo.new Bar();
    bar.setBlabla("hello");
    foo.setBar(bar);
    String fooxml = Xutil.java2xml(foo, Foo.class);
    System.out.println(fooxml);

and the whole xml is:

<?xml version="1.0" ?>
<me.mypackage.Foo>
    <bar>
        <blabla>hello</blabla>
        <outer-class reference="../.."/>
    </bar>
</me.mypackage.Foo>

Question1: How can I get rid of outer-class part?

Question2: how to make a pretty-formatted xml string with xstream?

In the previous post I have much emotional comments and make my question unclear, I edit my post and list the help I'm asking, thank you.

Answer 1

Use the PrettyPrintWriter to get the pretty format along with a StringWriter as follows:

public static String java2xml(Object obj, Class<?> T) {
    XStream xstream = new XStream(new StaxDriver());
    xstream.processAnnotations(T);
    StringWriter stringWriter = new StringWriter();
    xstream.marshal(obj, new PrettyPrintWriter(stringWriter));
    return stringWriter.toString();
}

As for the <outer-class reference="../.."/> issue, if you are not referencing any of Foo class members from Bar you can get rid of the <outer-class> tag by defining the Bar class as static