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    <p>There are a couple of awkward things with your example class:</p> <ul> <li>it's called People while it has a <code>price</code> and <code>info</code> (more something for objects, not people);</li> <li>when naming a class as a plural of something, it suggests it is an abstraction of more than one thing. </li> </ul> <p>Anyway, here's a demo of how to use a <code>Comparator&lt;T&gt;</code>:</p> <pre><code>public class ComparatorDemo { public static void main(String[] args) { List&lt;Person&gt; people = Arrays.asList( new Person("Joe", 24), new Person("Pete", 18), new Person("Chris", 21) ); Collections.sort(people, new LexicographicComparator()); System.out.println(people); Collections.sort(people, new AgeComparator()); System.out.println(people); } } class LexicographicComparator implements Comparator&lt;Person&gt; { @Override public int compare(Person a, Person b) { return a.name.compareToIgnoreCase(b.name); } } class AgeComparator implements Comparator&lt;Person&gt; { @Override public int compare(Person a, Person b) { return a.age &lt; b.age ? -1 : a.age == b.age ? 0 : 1; } } class Person { String name; int age; Person(String n, int a) { name = n; age = a; } @Override public String toString() { return String.format("{name=%s, age=%d}", name, age); } } </code></pre> <h2>EDIT</h2> <p>And an equivalent Java 8 demo would look like this:</p> <pre><code>public class ComparatorDemo { public static void main(String[] args) { List&lt;Person&gt; people = Arrays.asList( new Person("Joe", 24), new Person("Pete", 18), new Person("Chris", 21) ); Collections.sort(people, (a, b) -&gt; a.name.compareToIgnoreCase(b.name)); System.out.println(people); Collections.sort(people, (a, b) -&gt; a.age &lt; b.age ? -1 : a.age == b.age ? 0 : 1); System.out.println(people); } } </code></pre>
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    1. POHow to use Comparator in Java to sort
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    1. COThe AgeComparator and similar comparisons of integers can be simplified to return `a.age - b.age`
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    2. CO@Esko: comparison-by-subtraction "trick" is broken for general `int` http://stackoverflow.com/questions/2728793/java-integer-what-is-faster-comparison-or-subtraction/
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    3. CO@Esko: because of what polygenelubricants mentioned, I simply always do it like that, even though for an age (which will not become very large) the subtraction like you mention would do.
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