title: antlr - generate grammar from java source code
body: <p>I am wondering if I can generate ANTLR grammar from java source code.  I want to do some kind of research project, but I am just exploring different open sources to see which one is best. </p>
  
  <p>For ANTLR, do I always have to write a grammar and pass it to the ANTLR?</p>
  
  <p>Is there a way to generate grammar from an existing Java source code?</p>