Bugzilla – Full Text Bug Listing
| Summary: | [hashcode/equals] Suggestion for shorter Equals | ||
|---|---|---|---|
| Product: | [Eclipse Project] JDT | Reporter: | William Voorsluys <williamvoor> |
| Component: | UI | Assignee: | JDT-UI-Inbox <jdt-ui-inbox> |
| Status: | NEW --- | QA Contact: | |
| Severity: | enhancement | ||
| Priority: | P3 | ||
| Version: | 3.2.1 | ||
| Target Milestone: | --- | ||
| Hardware: | PC | ||
| OS: | Linux | ||
| Whiteboard: | |||
Moving to JDT/UI You can make it even shorter than that using a collection of 'and' combinators:
AnyClass other = (obj instanceof AnyClass ? (AnyClass)obj : null );
return
this == obj ||
(
obj != null &&
getClass() == obj.getClass() &&
!(this.field1 == null ? other.field1 == null : this.field1(equals(other.field1)) &&
!(this.field2 == null ? other.field2 == null : this.field2(equals(other.field2)) &&
);
i'm not sure how either the formatter would handle this, or the average programmer reading it, either. It would also be interesting to see (from a compiled approach) which one is better, or whether it makes any significant difference..
Alex.
|
I've been using the "Generate equals and hashCode" feature of Eclipse. I consider it very usefull except for the fact that it generates a too long equals method. On some of my code, I've changed some comparisons to get shorter equals methods with same functionality. On a class with 3 Object fields, it is possible to generate a 20 lines shorter equals, using comparison expressions. Like this: public class AnyClass { private Object field1; private Object field2; private Object field3; public boolean equals( Object obj ) { if ( this == obj ) return true; if ( obj == null ) return false; if ( getClass() != obj.getClass() ) return false; final AnyClass other = (AnyClass) obj; if ( !(this.field1 == null ? other.field1 == null : this.field1.equals( other.field1 )) ) return false; if ( !(this.field2 == null ? other.field2 == null : this.field2.equals( other.field2 )) ) return false; if ( !(this.field3 == null ? other.field3 == null : this.field3.equals( other.field3 )) ) return false; return true; } } In constrast to the equals generated by Eclipse: public boolean equals( Object obj ) { if ( this == obj ) return true; if ( obj == null ) return false; if ( getClass() != obj.getClass() ) return false; final AnyClass other = (AnyClass) obj; if ( this.field1 == null ) { if ( other.field1 != null ) return false; } else if ( !this.field1.equals( other.field1 ) ) return false; if ( this.field2 == null ) { if ( other.field2 != null ) return false; } else if ( !this.field2.equals( other.field2 ) ) return false; if ( this.field3 == null ) { if ( other.field3 != null ) return false; } else if ( !this.field3.equals( other.field3 ) ) return false; return true; } Certainly, some programmers do not like those expressions, as it may make the code harder to read. So, even this enhancement could be a "Clean Up" or an option when generating Equals, not necessarily the default implementation.