title: Building OpenJDK Library from source?
body: <p>I want to experiment with changes to the java library in java.lang, and possibly eventually other packages.  This means instead of using <code>rt.jar</code>, I want to  be able to separate out at least java.lang and compile to them.</p>
  
  <p>It is not possible to edit source code for classes in java.lang if using rt.jar because they are already found in rt.jar.</p>
  
  <p>I found the repo in mercurial: <a href="http://hg.openjdk.java.net/jdk8u/jdk8u/jdk/file/tip/src/share/classes/" rel="nofollow noreferrer">http://hg.openjdk.java.net/jdk8u/jdk8u/jdk/file/tip/src/share/classes/</a></p>
  
  <p>but no instructions on how to build. </p>
  
  <p>I just built jdk by installing a jdk9, then using mercurial:</p>
  
  <p>hg clone <a href="http://hg.openjdk.java.net/jdk/jdk/" rel="nofollow noreferrer">http://hg.openjdk.java.net/jdk/jdk/</a></p>
  
  <p>I can successfully build the java executable and all utilities, but rt.jar is not in this package.</p>