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    <p>Use the constructor overload which takes a <code>Comparator&lt;? super E&gt; comparator</code> and pass in a comparator which compares in the appropriate way for your sort order. If you give an example of how you want to sort, we can provide some sample code to implement the comparator if you're not sure. (It's pretty straightforward though.)</p> <p>As has been said elsewhere: <code>offer</code> and <code>add</code> are just different interface method implementations. In the JDK source I've got, <code>add</code> calls <code>offer</code>. Although <code>add</code> and <code>offer</code> have <em>potentially</em> different behaviour in general due to the ability for <code>offer</code> to indicate that the value can't be added due to size limitations, this difference is irrelevant in <code>PriorityQueue</code> which is unbounded.</p> <p>Here's an example of a priority queue sorting by string length:</p> <pre><code>// Test.java import java.util.Comparator; import java.util.PriorityQueue; public class Test { public static void main(String[] args) { Comparator&lt;String&gt; comparator = new StringLengthComparator(); PriorityQueue&lt;String&gt; queue = new PriorityQueue&lt;String&gt;(10, comparator); queue.add("short"); queue.add("very long indeed"); queue.add("medium"); while (queue.size() != 0) { System.out.println(queue.remove()); } } } // StringLengthComparator.java import java.util.Comparator; public class StringLengthComparator implements Comparator&lt;String&gt; { @Override public int compare(String x, String y) { // Assume neither string is null. Real code should // probably be more robust // You could also just return x.length() - y.length(), // which would be more efficient. if (x.length() &lt; y.length()) { return -1; } if (x.length() &gt; y.length()) { return 1; } return 0; } } </code></pre> <p>Here is the output: </p> <blockquote> <p>short</p> <p>medium</p> <p>very long indeed</p> </blockquote>
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    1. POHow do I use a PriorityQueue?
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    1. USJon Skeet
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    1. COHmm... just noticed... priorityQueue.comparator() "Returns the comparator used to order this collection, or null if this collection is sorted according to its elements natural ordering (using Comparable)." Does that mean I could just implement Comparable on my class as well?
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    2. COYes if you implement comparable in your class that would work as well
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    3. COYou could, yes. I wouldn't do so unless there's a single natural sort order for your class though. If there is, that's the right thing to do :)
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