Here is the whole code:->
private String createDocument(String content)
    {
        try {
        //    getUserInput("Hit enter to upload file......");
           
            System.out.println(content);
            //Retrieve Folder for file upload
            Folder folder = null;
            QueryResult qr = binding.query("Select Id, Name from Folder Where Name = 'CRDocuments'");  //the folder name where you would like the text file to be saved.
            if (qr.getSize() > 0)
            {
                System.out.println("The folder size is greater than zero");
                folder = (Folder) qr.getRecords(0);
            }
            System.out.println("folder name id:" + folder.getName());
            System.out.println("folder id is:"+folder.getId());
            //Create document object
            if(folder != null)
            {
               
                com.sforce.soap.enterprise.sobject.Document document = new com.sforce.soap.enterprise.sobject.Document();
                document.setName("InvoiceData");                //the name of the file
                document.setBody(content.getBytes());
              
                document.setFolderId(folder.getId());
               
                document.setContentType("application/x-pdf");
            
                documents = new com.sforce.soap.enterprise.sobject.Document[1];
                documents[0] = document;
               
                // create the object(s) by sending the array to the web service
               
                SaveResult[] sr = binding.create(documents);
                System.out.println("The number of the document is:"+sr.length);
                System.out.println();
                System.out.println("The body length is:"+document.getBodyLength());
                System.out.println("The text in the body is:"+document.getBody());
              
                for (int j = 0; j <sr.length; j++)
                {
                    if (sr[j].isSuccess())
                    {
                        System.out.println("A document was created with an id of: " + sr[j].getId());
                        return sr[j].getId();
                    }
                    else
                    {
                        for (int i = 0; i < sr[j].getErrors().length; i++)
                        {
                            com.sforce.soap.enterprise.Error err = sr[j].getErrors()[i];
                            System.out.println("Errors were found on item " + new Integer(j).toString());
                            System.out.println("Error code is: " + err.getStatusCode().toString());
                            System.out.println("Error message: " + err.getMessage());
                        }
                        return null;
                    }
                }
            //    getUserInput("\nHit return to continue...");
            }
        } catch (ApiFault af) {
            System.out
                    .println("\nFailed to create account, error message was: \n"
                            + af.getExceptionMessage());
            //getUserInput("\nHit return to continue...");
        } catch (Exception ex) {
            System.out
                    .println("\nFailed to create account, error message was: \n"
                            + ex.getMessage());
            //getUserInput("\nHit return to continue...");
        }
        return null;
    }

Is it because of the content in the body that the error is generated.The mime type is set as application/pdf what more do i need to do???In the case of jpeg files too I am facing the same problem.A document with no contents gets made.I am pretty sure its related to the content in the body.Kindly could you point out my mistakes.