<p>I'm getting a <code>NoSuchMethodError</code> error when running my Java program.  What's wrong and how do I fix it?</p>

This is usually caused when using a build system like
Apache Ant
that only compiles java files when the java file is newer than the class file.  If a method signature changes and classes were using the old version things may not be compiled correctly.  The usual fix is to do a full rebuild (usually "ant clean" then "ant").
Sometimes this can also be caused when compiling against one version of a library but running against a different version.