String Comparision ---please do help me

Question

Hai all,
I have a problem ,
1. i have an ArrayList which contains a list of all properties in the app, and an HashMap which contains the name of the file as the key and the string representation of the file as the value. i need to search the key of the ArrayList in the value of the HashMap(String representation of the file)
I have written the code as follows and its not working to get the values
Code:
HashMap hashReport=new HashMap();
               //Get the resource File Keys in the form of an ArrayList
               ArrayList rList=getResourceFiles(); // name of a function
               //Get the source Files and the String Representation of the
               //Source File in the form of a HashMap.
               HashMap sourcemap=createSourceMap(); // name of a function
               Set sourceSet=sourcemap.keySet();
               Iterator arrIter=rList.iterator();
                    while(arrIter.hasNext())
                         String arrString=(String)arrIter.next();
                         Iterator sourceIter=sourceSet.iterator();
                         while(sourceIter.hasNext())
                              String sourceStr=(String)sourceIter.next();
                              String valueStr=(String)sourcemap.get(sourceStr);
                              if ((arrString.indexOf(valueStr))!= -1)
                                   if(hashReport.put(arrString,sourceStr)== null)
                                        hashReport.put(arrString,sourceStr);
                                   else
                                        hashReport.put(arrString , ", "+ sourceStr);
please do help me in the regard.

Answer 1

hashReport.put(arrString , ", "+ sourceStr);This does not append sourceStr to the existing value. It just puts sourceStr, with a comma in front of it, in hashReport, overwriting any value that was already associated with arrString. If you want to append, you'll need to save the value from when you checked it earlier:
if(hashReport.put(arrString,sourceStr)== null)By the way, that kinds of make the following statement kind of extraneous. You only need to do extra work if the result of the first put is not null.
The approach you're taking may not be ideal anyway. Rather than creating long comma-delimited Strings, another approach you could take is to use Lists as the values of the result map, like this:
if ((valueStr.indexOf(arrString))!= -1) {
  List val = hashReport.get(arrString);
  if (val == null) {
    val = new ArrayList();
    hashReport.put(arrString, val);
  val.add(sourceStr);
}