Dumping a java object's properties

Is there a library that will recursively dump/print an objects properties? I'm looking for something similar to the console.dir() function in Firebug.

I'm aware of the commons-lang ReflectionToStringBuilder but it does not recurse into an object. I.e., if I run the following:

public class ToString {

    public static void main(String [] args) {
        System.out.println(ReflectionToStringBuilder.toString(new Outer(), ToStringStyle.MULTI_LINE_STYLE));
    }

    private static class Outer {
        private int intValue = 5;
        private Inner innerValue = new Inner();
    }

    private static class Inner {
        private String stringValue = "foo";
    }
}

I receive:

ToString$Outer@1b67f74[ intValue=5
innerValue=ToString$Inner@530daa ]

I realize that in my example, I could have overriden the toString() method for Inner but in the real world, I'm dealing with external objects that I can't modify.

From stackoverflow

• You could try XStream.

  XStream xstream = new XStream(new Sun14ReflectionProvider(
        FieldDictionary(new ImmutableFieldKeySorter())),
        new DomDriver("utf-8"));
  System.out.println(xstream.toXML(new Outer()));

  prints out:

  <foo.ToString_-Outer>
    <intValue>5</intValue>
    <innerValue>
      <stringValue>foo</stringValue>
    </innerValue>
  </foo.ToString_-Outer>

  You could also output in JSON

  And be careful of circular references ;)

  Kevin : Nice. I feel silly now because I use XStream a lot and I didn't even think of it.

  extraneon : Does that work with enum values? I believe (default) XML serialization using XMLEncoder.writeObject and hibernate have some problems with serializing enum values/types.

  cherouvim : @extraneon: sorry, I don't have much experience with Java 1.5 (enums etc)

• Maybe you could use an XML binding framework like XStream, Digester or JAXB for that.

• Scroll down for an example of dumping an object using reflection. http://stackoverflow.com/questions/37628/what-is-reflection-and-why-is-it-useful

  ---

  Or go directly to the answer.

• You can use ReflectionToStringBuilder with a custom ToStringStyle, for example:

  class MyStyle extends ToStringStyle {
  private final static ToStringStyle instance = new MyStyle();
  
  public MyStyle() {
   setArrayContentDetail(true);
   setUseShortClassName(true);
   setUseClassName(false);
   setUseIdentityHashCode(false);
   setFieldSeparator(", " + SystemUtils.LINE_SEPARATOR + "  ");
  }
  
  public ToStringStyle getInstance() {
   return instance;
  };
  
  @Override
  public void appendDetail(StringBuffer buffer, String fieldName, Object value) {
   if (!value.getClass().getName().startsWith("java")) {
    buffer.append(ReflectionToStringBuilder.toString(value, instance));
   } else {
    super.appendDetail(buffer, fieldName, value);
   }
  }
  
  @Override
  public void appendDetail(StringBuffer buffer, String fieldName, Collection value) {
   appendDetail(buffer, fieldName, value.toArray());
  }
  

  }

  And then you invoke it like:

  ReflectionToStringBuilder.toString(value, MyStyle.getInstance());
  

  Beware of circular references though!

  ---

  You can also use json-lib (http://json-lib.sourceforge.net) and just do:

  JSONObject.fromObject(value);
  

• JSONObject.fromObject(value)
  

  Does not work for Map objects with other keys than String. Maybe JsonConfig can handle this.