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    <p>First comment, this isn't really the correct use of an <code>Exception</code>. You should return a status code, maybe an <code>enum</code>.</p> <p>Second comment, <strong>never</strong> <code>throw new Exception()</code>. Create your own <code>Exception</code> class, otherwise you deal with <strong>all</strong> exceptions that could be thrown (<code>NullPointerException</code>, <code>ArrayIndexOutOfBoundsException</code> etc) in exactly the samne way. This is a bug waiting to happen.</p> <p>Now onto your problem. You <em>do</em> remove the item at index <code>i</code> from your <code>List</code>, but you <strong>always</strong> add it back in again with your call to <code>set</code>.</p> <p>Never remove items from a <code>Collection</code> while looping. In fact never loop over a collection by index unless you have to.</p> <p>Use an <code>Iterator</code> which has a <code>remove</code> method. This is the only (almost only) safe way to remove from a collection while looping.</p> <pre><code>final Iterator&lt;Bee&gt; myIter = cells.iterator(); while(myIter.hasNext()) { final Bee bee = myIter.next(); try{ bee.anotherDay(); }catch(Exception e){ myIter.remove(); } } </code></pre> <p>There is no need for you another day method to return <code>this</code> and there is no need to replace the reference in your <code>List</code> with exactly the same reference.</p> <p>Looking at your <code>eat</code> method, there is quite a bit of tidying that can happen; I would recommend this:</p> <pre><code>public boolean eat() throws Exception{ if(hive.honey &gt;= 2){ hive.takeHoney(2); if(health &lt; 3){ health++; } return true; } health -= 1; if(health == 0){ throw new BeeOutOfHealthException(); } return false; } </code></pre> <p>I.e. many of your assignments are rather confused. You don't need the <code>else</code> if you <code>return</code> in the <code>if</code>. Your nested <code>if</code> is a little odd - having an empty statement is certainly code smell.</p> <p>Further the logic of taking honey from the <code>hive</code> should really be <em>in the hive</em> for <code>takeHoney</code> should probably return a <code>boolean</code> if that amount of honey cannot be taken. That then reduces your method to:</p> <pre><code>public boolean eat() throws Exception{ if(hive.takeHoney(2)){ if(health &lt; 3){ health++; } return true; } health -= 1; if(health == 0){ throw new BeeOutOfHealthException(); } return false; } </code></pre>
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    1. CO+1 for the Iterator point. Removing an item whilst iterating it as in the question is a bug waiting to happen!
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