android - Check File exist before uploading DropBoxApi -

i using following code check file exist in dropbox before uploading avoid duplication.i using following line check returning false postexceute means "failed upload file".

entry existingentry= dropbox.metadata(path + "sample.txt",1,null,false,null); 

actual method:

 protected boolean doinbackground(void... params) {         final file tempdir = context.getcachedir();         file tempfile;         filewriter fr;         try {             tempfile = file.createtempfile("file", ".txt", tempdir);             fr = new filewriter(tempfile);             fr.write("test file uploaded using dropbox api android");             fr.close();              fileinputstream fileinputstream = new fileinputstream(tempfile);            entry existingentry= dropbox.metadata(path + "sample.txt",1,null,false,null);                  dropbox.putfile(path + "sample.txt", fileinputstream,                         tempfile.length(), null, null);                 tempfile.delete();              return true;         } catch (ioexception e) {             e.printstacktrace();         } catch (dropboxexception e) {             e.printstacktrace();         }         return false;     }    @override     protected void onpostexecute(boolean result) {         if (result) {             toast.maketext(context, "file uploaded successfully!",                     toast.length_long).show();         } else {             toast.maketext(context, "failed upload file", toast.length_long)                     .show();         }     }