What is the best standard style for a toString implementation? [closed]

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}" 

Answer 2

Personally, I find the mix of [] and {} not so easy to get an immediate view of the hierarchy.

I like this format (and I've seen it being used in a number of places):

SimpleClassName[prop1=value, prop2=value] SimpleClassName[prop1=value, prop2=NestedObject[prop3=value]] 

There's also the possibility to add an identifier with @, for example the default style for the commons-lang ToStringBuilder does that (using its own example):

Person@182f0db[name=John Doe,age=33,smoker=false]