Question

My problem is actually more nuanced than the question suggests, but wanted to keep the header brief.

I have a HashMap<String, File> of File objects as values. The keys are String name fields which are part of the File instances. I need to iterate over the values in the HashMap and return them as a single String.

This is what I have currently:

private String getFiles() {        Collection<File> fileCollection = files.values();     StringBuilder allFilesString = new StringBuilder();      for(File file : fileCollection) {         allFilesString.append(file.toString());     }     return allFilesString.toString(); } 

This does the job, but ideally I want the separate File values to be appended to the StringBuilder in order of int fileID, which is a field of the File class.

Hope I’ve made that clear enough.

Answer 1

Something like this should work:

List<File> fileCollection = new ArrayList<File>(files.values());  Collections.sort(fileCollection,                   new Comparator<File>()                   {                      public int compare(File fileA, File fileB)                       {                          final int retVal;                           if(fileA.fileID > fileB.fileID)                          {                              retVal = 1;                          }                          else if(fileA.fileID < fileB.fileID)                          {                              retVal = -1;                          }                          else                          {                              retVal = 0;                          }                           return (retVal);                                               }                  });