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POJava generic varargs method parameters
 

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    <p>I am wondering if there is an easy, <strong>elegant</strong> and reusable way to pass a string and a string array to a method that expect varargs.</p> <pre><code>/** * The entry point with a clearly separated list of parameters. */ public void separated(String p1, String ... p2) { merged(p1, p2, "another string", new String[]{"and", "those", "one"}); } /** * For instance, this method outputs all the parameters. */ public void merged(String ... p) { // magic trick } </code></pre> <p>Even if all the types are consistent (<code>String</code>) I cannot find a way to tell to the JVM to <em>flatten</em> p2 and inject it to the merged parameter list?</p> <p>At this point the only way is to create a new array, copy everything into it and pass it to the function.</p> <p>Any idea?</p> <hr> <h2>EDIT</h2> <p>Base on your proposal here is the generic method I'll use: </p> <pre><code>/** * Merge the T and T[] parameters into a new array. * * @param type the destination array type * @param parameters the parameters to merge * @param &lt;T&gt; Any type * @return the new holder */ @SuppressWarnings("unchecked") public static &lt;T&gt; T[] normalize(Class&lt;T&gt; type, Object... parameters) { List&lt;T&gt; flatten = new ArrayList&lt;&gt;(); for (Object p : parameters) { if (p == null) { // hum... assume it is a single element flatten.add(null); continue; } if (type.isInstance(p)) { flatten.add((T) p); continue; } if (p.getClass().isArray() &amp;&amp; p.getClass().getComponentType().equals(type)) { Collections.addAll(flatten, (T[]) p); } else { throw new RuntimeException("should be " + type.getName() + " or " + type.getName() + "[] but was " + p.getClass()); } } return flatten.toArray((T[]) Array.newInstance(type, flatten.size())); } normalize(String.class, "1", "2", new String[]{"3", "4", null}, null, "7", "8"); </code></pre>
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    1. CO[JLS 15.12.2.4](http://docs.oracle.com/javase/specs/jls/se7/html/jls-15.html#jls-15.12.2.4) is quite specific on what we can pass as vararg . It won't accept/flatten arrays, varargs or collections as a part of variable arity parameter
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    2. COSee my answer below, creating a list backed by a single value and an array may be better than copying. Flattening on the flight might be another better approach (Sebastian answer).
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