ToStringBuilder Style

Friday, 01 April 2011 12:37

Apache Commons ToStringBuilder styles

I have found the humble Java toString() to be one of the most useful and powerful techniques in debugging and troubleshooting Java applications. That is only true, unfortunately, when and if the developers on the team override the Object.toString() method to provide useful details. One of the disciplines i try to have while developing Java code is always overriding the default toString, equals, and hashCode methods.

An effective way to implement the toString method is using the Apache Commons library toStringBuilder class. According to your needs the library propose five styles. I propose you in this article to take a look at the different styles.

Assists in implementing Object.toString() methods. This java class enables a good and consistent toString() to be built for any class or object.

ToStringBuilder class aims to simplify the process by:

• allowing field names
• handling all types consistently
• handling nulls consistently
• outputting arrays and multi-dimensional arrays
• enabling the detail level to be controlled for Objects and Collections
• handling class hierarchies

Let's take the following class and apply different to string style using ToStringBuilder :

public class Person implements Comparable {
    private long id;
    private String firstName;
    private String lastName;
        ....
    public String toString(){
         return new ToStringBuilder(this,ToStringStyle.SIMPLE_STYLE)
             .appendSuper (super.toString())
             .append      ("first name", firstName)
             .append      ("last name", lastName)
             .toString();
    }
}

Styles availables

Styles Output samples

ch.javatutorial.Person@4310b053[first name=John,last name=Smith]

ch.javatutorial.Person@7b11a3ac[
  first name=John
  last name=Smith
]

ch.javatutorial.Person@7b11a3ac[John,Smith]

Person[first name=John,last name=Smith]

ch.javatutorial.Person@4310b053,John,Smith

Conclusion

The ToStringBuilder class is just one of many useful utility classes provided by the commons-lang library and the commons-lang library is just one of the useful libraries provided by the Apache Commons project.

Other related Java tutorial articles

• Hashcode and Equals Java Tutorial