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copied!<p>What are you doing in your method? If you're merely populating an existing array, then you don't need pass-by-reference semantics - either in .NET or in Java. In both cases, the reference will be passed by value - so changes to the <em>object</em> will be visible by the caller. That's like telling someone the address of your house and asking them to deliver something to it - no problem.</p> <p>If you <em>really</em> want pass-by-reference semantics, i.e. the caller will see any changes made to the parameter itself, e.g. setting it to null or a reference to a different byte array, then either method needs to return the new value, or you need to pass a reference to some sort of "holder" which contains a reference to the byte array, and which can have the (possibly changed) reference grabbed from it later.</p> <p>In other words, if your method looks likes this:</p> <pre><code>public void doSomething(byte[] data) { for (int i=0; i < data.length; i++) { data[i] = (byte) i; } } </code></pre> <p>then you're fine. If your method looks like this:</p> <pre><code>public void createArray(byte[] data, int length) { // Eek! Change to parameter won't get seen by caller data = new byte[length]; for (int i=0; i < data.length; i++) { data[i] = (byte) i; } } </code></pre> <p>then you need to change it to either:</p> <pre><code>public byte[] createArray(int length) { byte[] data = new byte[length]; for (int i=0; i < data.length; i++) { data[i] = (byte) i; } return data; } </code></pre> <p>or:</p> <pre><code>public class Holder<T> { public T value; // Use a property in real code! } public void createArray(Holder<byte[]> holder, int length) { holder.value = new byte[length]; for (int i=0; i < length; i++) { holder.value[i] = (byte) i; } } </code></pre> <p>For more details, read <a href="http://pobox.com/~skeet/csharp/parameters.html" rel="noreferrer">Parameter passing in C#</a> and <a href="http://pobox.com/~skeet/java/parameters.html" rel="noreferrer">Parameter passing in Java</a>. (The former is better written than the latter, I'm afraid. One day I'll get round to doing an update.)</p>

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