I assume the methods you want to exclude from javadoc are public methods that you don't want your client to use. In other words, these methods are deprecated. What you need to do is using the @Deprecated annotation. Like this:
@Deprecated public void badMethod() {
...
}
Now, the badMethod() is deprecated. If someone uses badMethod() in his code, he'll get a warning from the compiler (that he's using a deprecated method).
However, the @Deprecated annotation doesn't exclude the deprecated method from javadoc. Here's what you need to do in order to exclude the method from javadoc: When you generate javadoc, use the nodeprecated javadoc cmd line option. The -nodeprecated option prevents the generation of any deprecated API in the documentation. So if you use the @Deprecated annotation and generate javadoc with the -nodeprecated option, your bad method won't appear in the javadoc.
But in my opinion, you shouldn't exclude deprecated public methods from your javadoc. It's better if they appear in the documentation with an explanation of why the method is deprecated and what to use instead.