Troubleshoot sorting files by number size in Java

We want output (1.jpg, 2.jpg, 3.jpg, 10.jpg, 11.jpg, 20.jpg, 21.jpg, 31.jpg)

Suddenly see some online wording

Summary: Since you are dealing with a defined file name rule, you can also use regular expressions to simplify the use of

1file[] Files =file.listfiles ();2 if(files==NULL)returnResultfilename;3List<file> fileList =NewArraylist<file>();4  for(File f:files) {5 Filelist.add (f);6 }7 8Collections.sort (FileList,NewComparator<file>() {9 @OverrideTen      Public intCompare (file O1, file O2) { One         if(O1.isdirectory () &&o2.isfile ()) A             return-1; -         if(O1.isfile () &&o2.isdirectory ()) -             return1; the         returno2.getname (). CompareTo (O1.getname ()); -     } - }); -  +  for(File f:filelist) { -     if(F.isdirectory ()) { + Resultfilename.add (F.getpath ()); A ergodic (f,resultfilename); at}Else - Resultfilename.add (F.getpath ()); -}

But it outputs: (1.jpg, 10.jpg, 11.jpg, 2.jpg, 20.jpg, 21.jpg, 3.jpg, 31.jpg)

See this is clearly sorted in dictionary order since we want to sort by the integer size

1  Public Static voidMain (string[] args)throwsIOException {2File File =NewFile (path);3file[] Files =file.listfiles ();4arraylist<file> list =NewArraylist<>();5          for(File file2:files) {6 7 List.add (file2);8         }9         TenCollections.sort (list,NewComparator<file>() { One @Override A              Public intCompare (file O1, file O2) { -                 if(O1.isdirectory () &&o2.isfile ()) -                     return-1; the                 if(O1.isfile () &&o2.isdirectory ()) -                     return1; -Integer f =f (O1.getname ()); -Integer F2 =f (O2.getname ()); +                 returnInteger.compare (f, F2); -             } +         }); A          for(File file2:list) { at System.out.println (File2.getname ()); -         } -  -     } -      -     StaticInteger F (String filename) { in         intx = Filename.indexof (".")); -String string2 = filename.substring (0, x); to         Char[] cs =String2.tochararray (); +StringBuilder Builder =NewStringBuilder (); -          for(inti = 0; i < cs.length; i++) { the             if(Character.isdigit (Cs[i])) { * builder.append (Cs[i]); $             }Panax Notoginseng         } -         returnInteger.parseint (builder.tostring ()); the}

Using regular expressions

1  Public Final classFilestringImplementsComparable<filestring> {2     Private FinalString FileName;3     Private Final intPrefix_num;4Pattern number = Pattern.compile ("(\\d+) \ \. *");5 6      Publicfilestring (String fileName) {7          This. FileName =FileName;8Matcher Matcher =Number.matcher (fileName);9         if(Matcher.find ()) {TenPrefix_num = Integer.parseint (Matcher.group (1)); One}Else { APrefix_num = 0; -         } -     } the  - @Override -      Public intcompareTo (filestring o) { -         returnO.prefix_num > Prefix_num? -1:o.prefix_num = = Prefix_num? 0:1; +     } -  + @Override A      PublicString toString () { at         returnFileName; -     } -}

Troubleshoot sorting files by number size in Java