Undocumented String feature

Question

Hey
Take a look at this code and tell me where this is dosumentet i jdk.
          // display the result from the search, the most frequent first.
          // The string s is f.eks. /MyDocuments/test.html;Title_of_document
          // put the url and the title in a hashtable
          urls = new Hashtable();
          for (int k = int_tbl.length-1; k>=0;k--){
               String s = str_tbl[k];
               int slash = s.lastIndexOf(";");
               String kvasiUrl = s.substring(slash + 1,s.length());
               String ss = s.substring(0,slash);
               String OKUrl = new String(ss.toCharArray());
               urls.put(kvasiUrl, OKUrl);
               textArea.append(kvasiUrl+"\n");
          }//end for
          // set the current position to the first document in the list.
          textArea.setCaretPosition(1);
     }//end search
     // display the document in the browser, the target variable in the showDocument()
     // method is the target variable for html
     public void mouseClicked(MouseEvent evt){
//System.out.println(textArea.getSelectedText());
          if (!(textArea.getSelectedText().equals(""))){
               try{
                    String t = textArea.getSelectedText();
                    String s = (String)urls.get(t);
                    String mmm = getCodeBase().toString()+s;
                    String s3 = new String(mmm.toCharArray());
                    String s2 = new String(getCodeBase().toString()+s);
                    URL url = new URL(s3);
                    getAppletContext().showDocument(url,"_blank");
                    // This will result in the following c:\User\Myloginname\NULL
                    // the null part represents the variable s
                    // the former part is the codebase
                    // but a System.out.println(url.toString()) will print
                    // c:\User\Myloginname\MyDocuments\test.html
               }catch(MalformedURLException ext){
                    ext.printStackTrace();
               }//end try catch
          }//end if
     }//end mouseClicked
I have heard erlier that the String concat often can cause problem and the solution is to make a new string with the toCharArray or getBytes in the constructor, but this does not help in this situation. Thats why I've tried with both the s2 and s3 string.
Have anyone else encountered this problem??Or read something about it that can help me?
TheLaw

Answer 1

It would help if you wrote a simplified version of the program instead of trying to debug the most complicated possible code. You had some useful debugging code there but it's commented out.
In fact it is impossible to debug this code because it's impossible to tell what's selected in the text area. But whatever it is, it doesn't match anything that was used earlier as a key to the hashtable. So the urls.get() method returns null, which is what you are seeing. I don't see any control that requires the user to select exactly one line, and not the "\n" at the end, but maybe that's somewhere else in your program.
And that stuff at the end is just nonsense. This code:String OKUrl = new String(ss.toCharArray());is functionally equivalent to this:String OKUrl = ss;And I have never seen any point in "new String(someotherstring)", although people seem to use it for some reason.