Re: String parsing question.

Tom Anderson <>
Sun, 19 Apr 2009 23:38:27 +0100
On Sun, 19 Apr 2009, Arne Vajh?j wrote:

SpreadTooThin wrote:

I need to build a string based on the contents of another string.
(This string will be used to create a directory structure, but that's
irrelevant, I think.)

String dirName = "$PatientID/$StudyID/$SeriesID/Example - $ImageUID";

I need to parse this into a different string where the $Names have
been replaced with actual data.

So it might look something like:

constructedDir = "John Smith/Brain MRI/Sagital slices/Example - Image

What String methods or classes might help me do this simply?

Anything wrong with:

String dirName = "$PatientID/$StudyID/$SeriesID/Example - $ImageUID";
String constructedDir = dirName.replace("$PatientID", "John
Smith").replace("$StudyID", "Brain MRI").replace("$SeriesID", "Sagital
slices").replace("$ImageUID", "Image1");


Looks good to me.

One elaboration you might consider would be to get the $Names dynamically.
For instance, if you get the image info as a map:

// this is not real java syntax but the real syntax is too longwinded
Map<String, String> imageInfo = {
  "PatientID": "John Smith",
  "StudyID": "Brain MRI",
  "SeriesID": "Sagital slices",
  "ImageUID": "Image1"

And the template as a string:

String template = "$PatientID/$StudyID/$SeriesID/Example - $ImageUID";

You could do the construction like so:

String constructPath(String template, Map<String, String> namesAndValues) {
  String path = template;
  for (Map.Entry<String, String> nameAndValue: imageInfo.entrySet()) {
  String name = nameAndValue.getKey();
  String value = nameAndValue.getValue();
  // tip of the hat to Andreas here:
  if (value.contains("$")) throw new IllegalArgumentException("values cannot contain $ signs: name = " + name + ", value = " + value);
  path = path.replaceAll(("$" + name), value);
  // optional:
  if (path.contains("$")) throw new IllegalArgumentException("not all names were supplied with values in path format: format = " + format + " + ", names and values = " + namesAndValues);
  return path;

Also, there is something in the library you could apply -
java.text.MessageFormat. You'd have to rewrite your pattern like so:

String template = "{0}/{1}/{2}/{3}/Example = {4}";

And then do:

// you should do the following line once, and then keep the MessageFormat object
MessageFormat pathFormat = new MessageFormat(template);

String constructPath(String template, String patientID, String studyID, String seriesID, String imageUID) {
  return pathFormat.format(new String[] {patientID, studyID, seriesID, imageUID});

If you were desperate to keep the $-based format, you could write
something which translated that to a MessageFormat format. You might also
need to write something to map between the names and indexes in the format
array, depending on how the input arrives.


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