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    <p>It might result in slightly smaller bytecode, since the static methods won't get access to <code>this</code>. I don't think it makes any difference in speed (and if it did, it would probably be too small to make a difference overall).</p> <p>I would make them static, since I generally do so if at all possible. But that's just me.</p> <hr> <p><strong>EDIT:</strong> This answer keeps getting downvoted, possibly because of the unsubstantiated assertion about bytecode size. So I will actually run a test.</p> <pre><code>class TestBytecodeSize { private void doSomething(int arg) { } private static void doSomethingStatic(int arg) { } public static void main(String[] args) { // do it twice both ways doSomethingStatic(0); doSomethingStatic(0); TestBytecodeSize t = new TestBytecodeSize(); t.doSomething(0); t.doSomething(0); } } </code></pre> <p>Bytecode (retrieved with <code>javap -c -private TestBytecodeSize</code>):</p> <pre><code>Compiled from "TestBytecodeSize.java" class TestBytecodeSize extends java.lang.Object{ TestBytecodeSize(); Code: 0: aload_0 1: invokespecial #1; //Method java/lang/Object."&lt;init&gt;":()V 4: return private void doSomething(int); Code: 0: return private static void doSomethingStatic(int); Code: 0: return public static void main(java.lang.String[]); Code: 0: iconst_0 1: invokestatic #2; //Method doSomethingStatic:(I)V 4: iconst_0 5: invokestatic #2; //Method doSomethingStatic:(I)V 8: new #3; //class TestBytecodeSize 11: dup 12: invokespecial #4; //Method "&lt;init&gt;":()V 15: astore_1 16: aload_1 17: iconst_0 18: invokespecial #5; //Method doSomething:(I)V 21: aload_1 22: iconst_0 23: invokespecial #5; //Method doSomething:(I)V 26: return } </code></pre> <p>Invoking the static method takes two bytecodes (byteops?): <code>iconst_0</code> (for the argument) and <code>invokestatic</code>.<br> Invoking the non-static method takes three: <code>aload_1</code> (for the <code>TestBytecodeSize</code> object, I suppose), <code>iconst_0</code> (for the argument), and <code>invokespecial</code>. (Note that if these hadn't been private methods, it would have been <code>invokevirtual</code> instead of <code>invokespecial</code>; see <a href="http://java.sun.com/docs/books/jvms/second_edition/html/Compiling.doc.html#14787" rel="noreferrer">JLS §7.7 Invoking Methods</a>.)</p> <p>Now, as I said, I don't expect there to be any great difference in performance between these two, other than the fact that <code>invokestatic</code> requires one fewer bytecode. <code>invokestatic</code> and <code>invokespecial</code> should both be slightly faster than <code>invokevirtual</code>, since they both use static binding instead of dynamic, but I have no idea if either is faster than the other. I can't find any good references either. The closest I can find is <a href="http://www.javaworld.com/javaworld/jw-06-1997/jw-06-hood.html" rel="noreferrer">this 1997 JavaWorld article</a>, which basically restates what I just said:</p> <blockquote> <p>The fastest instructions will most likely be <code>invokespecial</code> and <code>invokestatic</code>, because methods invoked by these instructions are statically bound. When the JVM resolves the symbolic reference for these instructions and replaces it with a direct reference, that direct reference probably will include a pointer to the actual bytecodes.</p> </blockquote> <p>But many things have changed since 1997.</p> <p>So in conclusion... I guess I'm still sticking with what I said before. Speed shouldn't be the reason to choose one over the other, since it would be a micro-optimization at best.</p>
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    1. POShould private helper methods be static if they can be static
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    1. USMichael Myers
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    1. COall these negative votes for what seems like a very straightforward answer. +1 in the interests of truth, justice, ....
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      1. USSteve B.
    2. COThanks. (Although I could have deleted it and gotten a badge while it was at -3. :D )
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    3. COmaybe your guess that it is smaller bytecode is wrong? i'm +1'ing to set the universe right, at least until someone can show a reason for -3.. :)
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