Overriding equals() & hashCode() in sub classes … considering super fields

Question

Is there a specific rule on how Overriding equals() & hashCode() in sub classes considering super fields ?? k

Answer 1

I prefer to use EqualsBuilder (and HashcodeBuilder) from the commons-lang package to make my equals() and hashcode() methods a lot easier to read.

Example:

public boolean equals(Object obj) {
 if (obj == null) { return false; }
 if (obj == this) { return true; }
 if (obj.getClass() != getClass()) {
   return false;
 }
 MyClass rhs = (MyClass) obj;
 return new EqualsBuilder()
             .appendSuper(super.equals(obj))
             .append(field1, rhs.field1)
             .append(field2, rhs.field2)
             .append(field3, rhs.field3)
             .isEquals();
}