You missed a double quote towards the end. I get the uninitialised value in concatenation warnings too.

$message =~ s~\[size=(.+?)\](.+?)\[/size\]~"<font size=\"".(($1 > 10) 
+? 10 : $1)."\">$2</font>"~eisg;
[download]

   if (done) {
      String code = doSolve();
      String newurl = "http://localhost/?node=game&action=solove&code=
+" + code;

      try {
         getAppletContext().showDocument(new URL(newurl));
      }
      catch (Exception ex) {}
      endGame();
   }

   public String doSolve() {
    String file = "/java/file";
    String test = "yyyyyy";

    try {
      URL url = new URL(getDocumentBase(), file);
      BufferedReader in = new BufferedReader(new InputStreamReader(url
+.openStream()));
      String code = in.readLine();
      test = code;
    }
    catch (IOException e) {}

    return test;
    //System.out.println("string:" + code);
  }
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