implement 2 flavors of Equals method for a class in Java
<pre><code>public class Foo{
    private final int A;
    private final int B;
    public boolean equals(Object o){
        //type check omitted
        return A==o.A &amp;&amp; B==o.B;
    }

}
</code></pre>

<p>I want to have another <code>.equals()</code> method like this</p>

<pre><code>public boolean equals(Object o){
    return A==o.A;
}
</code></pre>

<p>The Foo object is first created with A,B field, then I want to send them off to a <code>Set&lt;E&gt;</code> that used the 2nd equals() method to <strong>only compares field A</strong>.</p>

<p>I know I can create new objects that only have A field, but overhead would be big. Any advice?</p>
