sclass CompileJavaToJar {
  S src;
  S dehlibs;
  File destJar;
  S progIDForRename;
  S progID;
  S sourceLevel = "11";
  IF1<S, File> compileSrcLib;
    
  // before you use this, add a RAM disk cleaner
  bool useRAMDisk;
  L<File> localLibraries;
  S mainClassName;
  File mainJava;
  new JavaCompilation jc;
  S compilerOutput;
  
  swappable void addMoreFiles(File classesDir) {}
  
  run {
    print("Compiling " + nChars(src));
    S dummyClass = "main";
    if (progIDForRename != null) {
      dummyClass = dummyMainClassName(progIDForRename);
      src += "\nclass " + dummyClass + "{}";
    }
    S md5 = md5(src);
    File jar = destJar;
  
    File srcDir = tempDir();
    S fileName = dummyClass + ".java";
    
    // derive name of main Java file from source
    LS tok = javaTok(src);
    S packageName = tok_packageName(tok);
    S cname = tok_firstClassName(tok);
    if (nempty(packageName)) {
      fileName = packageName.replace(".", "/") + "/" + cname + ".java";
      mainClassName = packageName + "." + cname;
    } else
      mainClassName = cname;
    mainJava = new File(srcDir, fileName);
    
    print("CompileJavaToJar main java: " + mainJava.getAbsolutePath());
    print("CompileJavaToJar mainClassName: " + mainClassName);
    saveTextFile(mainJava, src);
    File classesDir = useRAMDisk ? tempDirPossiblyInRAMDisk() : tempDir();
    saveTextFile(newFile(classesDir, fileName), src);
    //print("Compiling to " + f2s(classesDir));
    try {
      L<File> libraries = cloneList(localLibraries);
      
      Matcher m = Pattern.compile("\\d+").matcher(dehlibs);
      while (m.find()) {
        S libID = m.group();
        //print("libID=" + quote(libID));
        assertTrue(isSnippetID(libID));
        print("Adding library " + libID);
        temp tempSetTL(loadLibraryOrSrcLib_compiler, compileSrcLib);
        libraries.add(loadLibraryOrSrcLib(libID));
      }
      
      libraries.add(pathToJavaxJar());
        
      try {
        jc.srcDir = srcDir;
        jc.libraries = libraries;
        jc.classesDir = classesDir;
        jc.sourceLevel = sourceLevel;
        jc.run();
        compilerOutput = jc.compilerOutput;
      } catch (Throwable e) {
        compilerOutput = jc.compilerOutput;
        //fail("Compile Error. " + cleanJavaCompilerOutput(compilerOutput) + " " + e);
        compilerOutput = indentx("> ", cleanJavaCompilerOutput(compilerOutput));
        if (!swic(e.getMessage(), "Java compiler returned errors."))
          compilerOutput = appendWithNewLine(compilerOutput, str(e));
        //printStackTrace(e);
        fail(compilerOutput, e);
      }
      
      compilerOutput = cleanJavaCompilerOutput("Annotation processing got disabled, since it requires a 1.6 compliant JVM");
  
      if (nempty(compilerOutput)) {
        print("Compiler said: " + compilerOutput);
        //fail("Compile Error. " + compilerOutput);
      }
    
      // sanity test
      if (!anyFileWithExtensionInDir(classesDir, ".class")) {
        //printWithIndent("SRC> ", src);
        fail("No classes generated (was compiling " + nChars(src) + ")");
      }
          
      // add sources to .jar
      //saveTextFile(new File(classesDir, "main.java"), src);
      
      // add information about libraries to jar
      if (nempty(dehlibs))
        saveTextFile(new File(classesDir, "libraries"), dehlibs);
        
      // add prog id to jar
      saveTextFile(new File(classesDir, "progID"), progID);
  
      // save pointer to main Java source    
      //saveTextFile(new File(classesDir, "main-src"), fileName);
      
      addMoreFiles(classesDir);
    
      //print("Zipping: " + classesDir.getAbsolutePath() + " to " + jar.getAbsolutePath());
      dir2zip_recurse_verbose = false;
      long time = sysNow();
      int n = dir2zip_recurse(classesDir, jar); // cache on success only
      done2_always(time, nFiles(n) + " zipped");
    } finally {
      if (isInRAMDisk(classesDir)) deleteDirectory(classesDir);
    }
  }
}

Began life as a copy of #1011328