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copied!<p>Sure there is. You need a java.lang.Class instance initially, for the target class you wish to create. Depending on your structure, this might either be passed in by a caller (if they're supplying the concrete class they want created), or you can statically access the class variable (e.g. <code>MyFooImpl.class</code>).</p> <p>The simplest way is to call <a href="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Class.html#newInstance()" rel="nofollow noreferrer">Class.newInstance()</a>. This invokes the default, no-arg constructor (assuming there is one for the class; if not it throws an exception).</p> <p>If you need to invoke a particular constructor with some argument, you need to call <a href="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Class.html#getConstructor(java.lang.Class...)" rel="nofollow noreferrer">Class.getConstructor()</a> to get a Constructor instance, which you can then call <a href="http://java.sun.com/j2se/1.5.0/docs/api/java/lang/reflect/Constructor.html#newInstance(java.lang.Object...)" rel="nofollow noreferrer">newInstance</a> on.</p> <p>In all cases you'll need to deal with reflection exceptions that you wouldn't get if invoking the constructor directly.</p> <p><strong>Big edit</strong>: I assume your question was about creating instances of a class via reflection. However I'm beginning to think that you're asking about <em>defining</em> new classes through at runtime. If so, then reflection won't help you here - you'd need to invoke a compiler programatically, which I believe can be done but I'm not 100% on the details. I think you'd also have to go through some hoops to get the ClassLoader to pick up your new class too.</p>

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