[LANG-1551] EqualsBuilder with Lambdas

• Type: Improvement
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 3.9
• Component/s: lang.builder.*
• Assignee: Unassigned
• Reporter: Bruce Brouwer
• Created: 03/Jun/20 21:03
• Updated: 03/Jun/20 21:03

Description

Has it been considered to use lambdas to make it easier to write equals methods? 

public boolean equals(final Object obj) {
  return new EqualsBuilder<MyClass>(this, obj)
    .append(it -> it.field)
    .appendSuper(super.equals(obj)
    .isEquals();
}

I know this is incompatible with the current EqualsBuilder so maybe a new class, or something like this would work instead:

public boolean equals(final Object obj) {
 return EqualsBuilder.with(this, obj) // with returns a generic type similar to EqualsBuilder
   .append(it -> it.field)
   .appendSuper(super.equals(obj)
   .isEquals();
}

It helps eliminate all the boilerplate code of checking object types and could even skip calling the lambdas if it already knew it was not equal.