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copied!<p>There are a few ways:</p> <p><strong>Double brace initialization</strong></p> <p>This is a technique which creates an anonymous inner class which has an instance initializer which adds <code>String</code>s to itself when an instance is created:</p> <pre><code>Set<String> s = new HashSet<String>() {{ add("a"); add("b"); }} </code></pre> <p>Keep in mind that this will actually create an new subclass of <a href="http://java.sun.com/javase/6/docs/api/java/util/HashSet.html" rel="noreferrer"><code>HashSet</code></a> each time it is used, even though one does not have to explicitly write a new subclass.</p> <p><strong>A utility method</strong></p> <p>Writing a method that returns a <a href="http://java.sun.com/javase/6/docs/api/java/util/Set.html" rel="noreferrer"><code>Set</code></a> which is initialized with the desired elements isn't too hard to write:</p> <pre><code>public static Set<String> newHashSet(String... strings) { HashSet<String> set = new HashSet<String>(); for (String s : strings) { set.add(s); } return set; } </code></pre> <p>The above code only allows for a use of a <code>String</code>, but it shouldn't be too difficult to allow the use of any type using generics.</p> <p><strong>Use a library</strong></p> <p>Many libraries have a convenience method to initialize collections objects.</p> <p>For example, <a href="http://code.google.com/p/google-collections/" rel="noreferrer">Google Collections</a> has a <a href="http://google-collections.googlecode.com/svn/trunk/javadoc/com/google/common/collect/Sets.html#newHashSet(E...)" rel="noreferrer"><code>Sets.newHashSet(T...)</code></a> method which will populate a <code>HashSet</code> with elements of a specific type.</p>

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