Re: Why this overloading example works this way?

From:
"Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org>
Newsgroups:
comp.lang.java.programmer
Date:
Fri, 8 Dec 2006 20:39:37 -0000
Message-ID:
<4579cd69$0$623$bed64819@news.gradwell.net>
Oliver Wong wrote:

  @Override
  public boolean equals(Object other) {
    if (other instanceof SomeClass) {
      return equals((SomeClass)other);
    }
    return false;
  }

  public boolean equals(SomeClass other) {
    if (this.field1 != other.field1) {
      return false;
    }
    if (!this.field2.equals(other.field2)) {
      return false;
    }
    return true;
  }


Minor nitpick: the two methods treat null differently. Consider

    SomeClass sc1 = new SomeClass();
    SomeClass sc2 = null;
    Object o = sc2;

    scl.equals(o); // false
    sc1.equals(sc2); // boom
    sc2 == o; // true

Personally, I don't consider it unreasonable to <boom> when comparing against
null, /and/ not attempting to follow the contract of Object.eqauls(Object).
But where that's the case, I'd prefer to call the comparison method something
other than equals(<something>) even though it is formally an unrelated method.

    -- chris

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