What is the best standard style for a toString implementation?

Question

We have a lot of objects for which we like to implement a simple toString to output attributes of the object. Some of these attributes may be complex objects themselves.

Is there any standard, or simply just a best practice for a style? I'm thinking something like:

[SimpleClassName] { prop1:value, prop2:value }

In which case a nested value would look like:

[SimpleClassName] { prop1:value, prop2:[NestedObject] { prop3:value}}

We are using Java but I find myself asking the same question in most languages!

Answer 1

I think the format produced by Guava's MoreObjects.toStringHelper() is pretty nice, but it's mainly just good to have some consistent format that you use:

public String toString() {
  return Objects.toStringHelper(this)
      .add("prop1", prop1)
      .add("prop2", prop2)
      .toString();
}

// Produces "SimpleClassName{prop1=foo, prop2=bar}"