Merging 2 folders in java keeping the common files by changing its name -

there 15 folders have. every folder has similar sub-structure. merge contents of folders: 1. taking 2 folders @ time 2. taking 3 folders @ time such both files same name saved.

example:

folder 1  ---pqr ------abc.txt ------xyz.txt  folder 2 ---pqr ------abc.txt 

after merging:

folder 3 ---pqr -------abc.txt -------abc.txt(2) -------xyz.txt 

please me java code. in advance.

this have done far in netbeans.

package merger; import org.apache.commons.io.fileutils; import java.io.file; import java.io.ioexception; import java.util.hashmap; import java.util.map;  public class merger {      public static void main(string[] args)     {      }      public void copydifferentfolderfilesintoone(string mergedfolderstr,             string... foldersstr) throws ioexception     {          final file mergedfolder = new file(mergedfolderstr);         final map<string, file> filesmap = new hashmap<> ();         (string folder : foldersstr) {             updatefilesmap(new file (folder), filesmap, null);         }          (final map.entry<string, file> fileentry : filesmap.entryset()) {             final string relativename = fileentry.getkey();             final file srcfile = fileentry.getvalue();             fileutils.copyfile (srcfile, new file (mergedfolder, relativename));         }     }      private void updatefilesmap(final file basefolder, final map<string, file> filesmap,             final string relativename)     {         (final file file : basefolder.listfiles()) {             final string filerelativename = getfilerelativename (relativename, file.getname());              if (file.isdirectory())             {                            updatefilesmap(file, filesmap, filerelativename);             }             else {                 final file existingfile = filesmap.get (filerelativename);                 if (existingfile == null || file.lastmodified() > existingfile.lastmodified() ) {                     filesmap.put (filerelativename, file);                 }             }         }     }      private string getfilerelativename(final string basename, final string filename)     {         return basename == null ? filename : basename + "/" + filename;     }     }