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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.
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.
