Using Google Guava's Objects.ToStringHelper

问题

I used ToStringBuilder.reflectionToString(class) in commons-lang, to implement toString() for simple DTOs. Now I'm trying to use Google Guava instead of Apache commons library. And I found Objects.ToStringHelper in Guava. But it's too verbose if there're lots of members in the class. For example:

@Override
public String toString() {
    return MoreObjects.toStringHelper(this.getClass()).add("name", name)
            .add("emailAddress", emailAddress)
            .add("department", department).add("yearJoined", yearJoined)
            .toString();
}

is much simpler if I use commons-lang:

@Override
public String toString() {
    return ToStringBuilder.reflectionToString(this);
}

Is there any better ways to implement toString() with Guava, not with commons-lang?

Guava docs

回答1:

I have a little trick for Guava's com.google.common.base.MoreObjects.toStringHelper(). I configured IntelliJ IDEA to use it when auto-generating toString() methods. I assume you can do the same in Eclipse. Here's how to do it in Intellij:

go inside a class
hit Alt + Insert to popup the "Generate" menu
choose toString()
click the "Settings" button
go to the "Templates" tab
create a new template named "Guava's MoreObjects.toStringHelper()" (I did it by copying the "ToStringBuilder" template)

change the template to:

public String toString() {
#set ($autoImportPackages = "com.google.common.base.MoreObjects")
    return MoreObjects.toStringHelper(this)
#foreach ($member in $members)
    .add("$member.name", $member.accessor)
#end
    .toString();
}

save the template, close the "Settings" and "Generate toString()" windows
you can now choose the Guava's MoreObjects.toStringHelper() template when generating toString() methods

When you add a new field to the class, simply re-generate the toString() method (IDEA will ask you to confirm that you want to replace the existing toString() method).

回答2:

MoreObjects.toStringHelper is intended to help you write toString() methods with a consistent format easily, but it gives you control over what fields you include in toString() and should have performance comparable to writing it out manually. reflectionToString is shorter to type, but it doesn't give you explicit control over the included fields and, well, it uses reflection. I don't see it as a better alternative.

As a side note, I think using toStringHelper looks a lot cleaner if you put one add call per line.

Guava docs

回答3:

There is a plugin http://sourceforge.net/projects/guavaeclipse/ (really small one) which can generate toString methods (and equals hashcode as well) using Guava classes. This is a nice solution because generated methods are really small and do not clutter the class.

回答4:

It is worth noting that Objects.toStringHelper has been deprecated (to be removed completely in June 2016) in favor of MoreObjects.toStringHelper. I have copied the default Guava template in my Intellij IDE into a new one that uses the MoreObjects instead. Cheers.

Guava docs

回答5:

Of the available Eclipse plugins, guavaeclipse is still using MoreObjects.toStringHelper, but Jenerate uses MoreObjects.toStringHelper and works like a charm.

Guava docs

回答6:

In eclipse you can create a template (not as powerfull as IntelliJ https://stackoverflow.com/a/9445402/1301197 ). It will not loop across all member fields for you but you get at least the surrounding code

windows > preferences > Java > Editor > Templates

${:import(com.google.common.base.MoreObjects)}
@Override
public String toString() {
    return MoreObjects.toStringHelper(this)
    .add("${field}",${field})
    .toString();
}

This will add the import and you will get something like this if you enter id as the field. Then up to you to add the remaining fields.

public String toString()
{
    return MoreObjects.toStringHelper(this).add("id", id).toString();
}

Note that there is probably a better solution by using eclipse toString() generator and creating a custom toString() builder. But this is too much work for a lazy man like me.

Right click then source > generate toString() and select Custom toString() Builder inside code style.

来源：https://stackoverflow.com/questions/9444573/using-google-guavas-objects-tostringhelper

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tostring