Comments on: Easy toString/equals/hashcode

By: Free Credit Report

Free Credit Report — Wed, 25 Apr 2007 16:59:55 +0000

Free Credit Report

Nice blog! Great design and cool topics.

By: Cyrill

Cyrill — Tue, 12 Oct 2004 08:06:08 +0000

Mark your collections with the transient keyword and do not include them into the hash code.

public int hashCode() {
return HashCodeBuilder.reflectionHashCode(this, false);
}

Regards,

Cyrill

By: Leon van Tegelen

Leon van Tegelen — Mon, 30 Aug 2004 21:37:16 +0000

On the StringBuffer vs "+" issue. Check out these sites: old (2000) newer (2003) Or even this one . The compiler used also has an impact. I measured it and it checks out. Using the StringBuffer or the "+" method depends on what you are doing. If you are appending in a loop use StringBuffer, if not the difference is neglectable. So when in doubt use StringBuffer I would say...

By: Leon van Tegelen

Leon van Tegelen — Mon, 30 Aug 2004 18:29:36 +0000

Be sure to use commons-lang version 2.0. Oracle JDeveloper ships with an older version which does not have the builder package, I spend a few frustrating moments figuring out what Ant was trying to tell me…

By: AH

AH — Mon, 30 Aug 2004 12:43:40 +0000

Using StringBuffer.append instead of + for efficiency reasons worked well for JDK 1.1. But the compiler is much better now.
This sequence String s = “a” + “b” + variable + “x”; is the same efficiency as using a StringBuffer.

By: Zeger Hendrikse

Zeger Hendrikse — Mon, 30 Aug 2004 12:26:41 +0000

I also like Rod Johnson's approach, e.g.:


public String toString()
{
    StringBuffer sb = new StringBuffer(getClass().getName() + ": ");
    sb.append("Primary key=" + id + "; ");
    sb.append("Surname='" + getSurname() + "'; ");
    sb.append("Forename='" + getForename() + "'; ");
    sb.append(" systemHashcode=" + System.identityHashCode());
    return sb.toString();
}

Note the use of StringBuffer instead of using the "+" operator (efficiency!). I like the use of the apostrophes in particular, very useful in detecting leading or trailing white spaces! But of course, if you have the avail over the Jakarta common's lang package, the posted version is much less work!