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POIs it better to use a for-each loop in a function, or a while loop and a “found” variable?
 

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  1. POIs it better to use a for-each loop in a function, or a while loop and a “found” variable?
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    <p> </p> <p>I'm taking an online intro-to-Java course. In the lesson on <code>ArrayList</code>s, there's an exercise in which we're given an <code>ArrayList</code> of <code>Picture</code> objects, and asked to call <code>draw()</code> on the first <code>Picture</code> that's in portrait orientation. We're given some code to start with:</p> <pre class="lang-java prettyprint-override"><code>// BlueJ project: lesson7/gallery8 // Find and draw the first portrait in the gallery. // Notice the pseudocode from the instructions has been started for you; your task is to complete it. import java.util.ArrayList; public class ListOfPictures { public static void main(String[] args) { ArrayList&lt;Picture&gt; gallery = new ArrayList&lt;Picture&gt;(); gallery.add(new Picture("degas1.jpg")); gallery.add(new Picture("gaugin1.jpg")); gallery.add(new Picture("monet1.jpg")); gallery.add(new Picture("monet2.jpg")); gallery.add(new Picture("renoir1.jpg")); int i = 0; boolean found = false; while () { } if (found) { ....draw(); } } } </code></pre> <p>It seemed pretty clear to me what they expected us to do. Still, I thought it would be better to make a function and <code>return</code> from a for-each loop, rather than using a <code>found</code> and a counter variable. This is what I came up with:</p> <pre class="lang-java prettyprint-override"><code> public static void main(String[] args) { // declare/initialize/populate gallery Picture firstPortrait = findFirstPortrait(gallery); if (firstPortrait != null) firstPortrait.draw(); } private Picture findFirstPortrait(ArrayList&lt;Picture&gt; gallery) { for (Picture pic : gallery) if (pic.getHeight() &gt; pic.getWidth()) // pic is in portrait return pic; return null; // there aren't any images in portrait } </code></pre> <p>They seemed to really dislike it, though. When I submitted my code, I got this back:</p> <pre class="lang-none prettyprint-override"><code>ListOfPictures.java: Keep looking for matches while found is false Score 0 </code></pre> <p>Which is the better way of doing this? In general, should I avoid using “flag” variables like that?</p> <p><strong>EDIT:</strong> Yes, it is automatically graded. I've actually gotten an error on other exercises saying that the grader didn't know how to deal with my code and that I should post it on the forum (which looks suspiciously like Stack Overflow, only that no one seems to know <a href="https://stackoverflow.com/about">how to use it</a>).</p> <p>I <em>will</em> be linking to this question on the forum. :)</p>
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    1. USCommunity
    1. USAntonio
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    1. COYour grader was misguided.
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      1. USroippi
    2. COLooks like your solution is valid, I'd go back and find out whether the tutor has a good reason to mark you down or is just stupid ;-)
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      1. USJohn3136
    3. COTime to quit those classes.
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      1. USRavi Thapliyal
 

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