Re: Improving String.equals() implementation

Lew wrote:
Eric Sosman wrote:
/** A trivial class with a "safe" equals() method */
private static class Safe {
private final int value;
private Safe(int value) {
this.value = value;
}

public boolean equals(Object obj) {
return (obj instanceof Safe) && (value == ((Safe)obj).value);
}
}

/** A trivial class with a "fast" equals() method. */
private static class Fast {
private final int value;
private Fast(int value) {
this.value = value;
}

public boolean equals(Object obj) {
return (value == ((Fast)obj).value);
}
}

}

I think I caught the obvious gotchas.

The behaviors of the two 'equals()' implementations are not
equivalent.

A fair benchmark would compare methods with the same behaviors.

I don't understand your objection. The methods are different
because the point of the exercise was to measure the performance
impact of their difference, as a follow-up to Lothar Kimmeringer's
point about the cost of a "redundant" instanceof test. If both
methods had (or both lacked) the test, what would be measured?

--
Eric.Sosman@xxxxxxx
.

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