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POUnwrapping a Guava Optional in a single expression
 

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    <p>As a Scala developer who also works in <code>GWT</code>, I welcome the addition of <code>Optional</code> to Guava.</p> <p>One of our most common use cases of <code>Optional</code> is when returning optional values from methods (as suggested by the answer to <a href="https://stackoverflow.com/questions/9561295/whats-the-point-of-guavas-optional-class">What&#39;s the point of Guava&#39;s Optional class</a>.</p> <p>In scala, I often write code like this:</p> <pre><code>def someExpensiveOperation(params: Type): Option[ResultType] = ... someExpensiveOperation(params).foreach({ val =&gt; doSomethingWithVal (val) }) </code></pre> <p>Guava's Option does not seem to allow anything more elegant than something like this:</p> <pre><code>Optional&lt;MyType&gt; optionalResponse = someExpensiveOperation(params); if (optionalResponse.isPresent()) { doSomethingWithVal(optionalResponse.get()) } </code></pre> <p>The local variable is redundant, and it requires repeating a pattern which could be abstracted (the <code>if (optional.isPresent()) { doSomethingWith(optional.get()) }</code> ).</p> <p>The other option would be to call the method which returns an <code>Optional</code> twice:</p> <pre><code>if (someExpensiveOperation(params).isPresent()) { doSomethingWithVal(someExpensiveOperation(params).get()) } </code></pre> <p>But that is clearly undesirable, since it invoked an expensive operation multiple times unnecessarily.</p> <p>I'm curious how other people have handled this very-common case (perhaps by writing a static utility method like <code>&lt;T&gt;useIfPresent(Optional&lt;T&gt; val, Closure&lt;? super T&gt; closure)</code>?) or if anyone has found more elegant solutions.</p> <p>Also, if anyone knows why a method like <code>Optional.foreach(Closure&lt;? super T&gt; closure)</code> (but hopefully better named) was omitted, I would be curious to hear the rationale.</p>
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