[jira] [Created] (LANG-1493) Performance of Reflection for equals and hash code can be improved over EqualsBuilder

["Miguel Munoz (Jira)" <ji...@apache.org>]

Miguel Munoz created LANG-1493:
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             Summary: Performance of Reflection for equals and hash code can be improved over EqualsBuilder
                 Key: LANG-1493
                 URL: https://issues.apache.org/jira/browse/LANG-1493
             Project: Commons Lang
          Issue Type: New Feature
          Components: lang.*
            Reporter: Miguel Munoz


The EqualsBuilder class is very inefficient. It reflects through all the fields of a class every time it needs to do a comparison. A faster approach would be to do the reflection once when the class loads, and re-use it for each instance. This change, however, needs a different API and couldn't be a drop-in replacement for EqualsBuilder. Instead it would need to be a new class.
 I have written a class that can do this. Performance tests show that it runs up to 20 times faster, depending on how many fields it needs to compare before finding a difference.

You can try the class out by going to [https://github.com/SwingGuy1024/DogTags].

The API currently works like this:
 
{code:java}
public class MyClass {
  // fields and methods
  
  private static final DogTag<MyClass> dogTag = DogTag.from(MyClass.class);
  
  @Override
  public boolean equals(Object that) {
    return dogTag.doEqualsTest(this, that);
  }
  
  @Override
  public int hashCode() {
    return dogTag.doHashCode(this);
  }
}{code}

I'm looking into changing the API, so it would work like this:


{code:java}
public class MyClass {
  // fields and methods here ...
  
  private final DogTag<MyClass> dogTag = DogTag.from(MyClass.class, this);
  
  @Override
  public boolean equals(Object other) {
    return dogTag.doEqualsTest(other);
  }
  
  @Override
  public int hashCode() {
    return dogTag.doHashCode();
  }
}
{code}

(I'm a new contributor, so I'm not sure if this is the best way to suggest a whole new class. But I'd like to contribute to give people a faster way of doing Reflection Equals.)



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