Using wildcard when listing files in directory with java -

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why wildcard not work in java code below?
request looks http://localhost:8080/app/dataaccess?location=dublin

rob@work:~$ ls /usr/local/customappresults/dublin/*/.history /usr/local/customappresults/dublin/team1/.history /usr/local/customappresults/dublin/team2/.history /usr/local/customappresults/dublin/team3/.history

servlet code (dataaccess.java).
(dataaccess.java:27) refers loop ..

protected void doget(httpservletrequest request, httpservletresponse response) throws servletexception, ioexception {          file[] files = finder("/usr/local/customappresults/" +                              request.getparameter("location") + "/*/");          (int = 0; < files.length; i++){                      system.out.println(files[i].getname());         }     }      private file[] finder(string dirname) {          file dir = new file(dirname);          return dir.listfiles(new filenamefilter() {             public boolean accept(file dir, string filename) {                 return filename.endswith(".history");             }         });     }

error:

the server encountered internal error prevented fulfilling request.     java.lang.nullpointerexception     com.example.servlets.dataaccess.doget(dataaccess.java:27)     javax.servlet.http.httpservlet.service(httpservlet.java:621)     javax.servlet.http.httpservlet.service(httpservlet.java:728)

the method public file[] listfiles(filenamefilter filter)

returns null if abstract pathname not denote directory, or if i/o error occurs.

(http://docs.oracle.com/javase/7/docs/api/java/io/file.html)

so, why situation? trying use wildcard char (*) evaluated shell, won't evaluated in new file(path). new file(path) constructor works exact paths.

things directoryscanner (apache ant) or fileutils (apache commons-io) solve problem. see comments above further details on possible solutions, including java 7 nio approach (files.newdirectorystream( path, glob-pattern )).


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