Iterate faster over a large collection of files (objects) inside an Observable List (JavaFX 8) - javafx

Question

I have an excel file that contains all the filenames of the Images. The path of these images are stored in an Observable Collection via <File> class which came from the folder that contains all of the images. My goal is to create a hyperlink of these filenames by matching it through the pool of image file collection.
I would like to ask if how can I iterate faster through a large collection of file classes in order to get their paths easily.
For example:
Image name from Excel :
ABC_0001
The Full path from the collection must be:
C:\Users\admin\Desktop\Images\ABC_0001.jpg
In order to get their full path, I perform the iteration through Stream.
My procedures:
Extract data using Apache POI.
Stream through the Image Collection by converting each data into
their base filenames vs extracted data.
Get the result and store the fullpath on the object via
getAbsolutePath().
Code:
//storage during iteration
ObservableList<DetailedData> dataCollection = FXCollections.observableArrayList()
//Image collection containing over 13k Images listed via commons-io
ObservableList<File> IMAGE_COLLECTION = FXCollections.observableArrayList(FileUtils.listFiles(browsedFOLDER, new String[]{"JPG", "JPEG", "TIF", "TIFF", "jpg", "jpeg", "tif", "tiff"}, true));
//Sheet data
Sheet sheet1 = wb.getsheetAt(0);
for (Row row: sheet1)
{
DetailedData data = new DetailedData();
//extracted data from excel
String FILENAME = row.getCell(0,Row.MissingCellPolicy.CREATE_NULL_AS_BLANK).getStringCellValue();
//to be filled up based on stream result.
String IMAGE_SOURCE = null;
//stream code with the help of commons-io
File IMAGE = IMAGE_COLLECTION.stream().filter(e -> FilenameUtils.getBaseName(e.getName()).toLowerCase().equals(FILENAME.toLowerCase())).findFirst().orElse(null);
if (IMAGE != null)
IMAGE_SOURCE = IMAGE.getAbsolutePath();
data.setFileName(FILENAME);
data.setFullPath(IMAGE_SOURCE);
dataCollection.add(data);
}
Result:
Excel rows = 9,400
Image Files = 13,000
Iteration Time = 120,000ms
Are the results should appear normal or it can become faster?
I tried using parallelStream() and the results went faster but it consumes higher CPU usage.

Answer 1

This code should speed your code up a lot, but there are a few questions about your code.
ObservableList<DetailedData> dataCollection = FXCollections.observableArrayList() Why are you using ObservableList? Why is this a list of DetailedData and not File. Given that detailed data has setFileName and setFullPath. File already has these.
ObservableList<File> IMAGE_COLLECTION = FXCollections.observableArrayList(FileUtils.listFiles(browsedFOLDER, new String[]{"JPG", "JPEG", "TIF", "TIFF", "jpg", "jpeg", "tif", "tiff"}, true)); Why ObservableList?
These two are small things, but I am curious.
So what I think you should do is use a Map. Your code should look something like the code below.
//storage during iteration
List<DetailedData> dataCollection = new ArrayList();
//Image collection containing over 13k Images listed via commons-io
List<File> IMAGE_COLLECTION = new ArrayList(FileUtils.listFiles(new File("C:\\Users\\blj0011\\Pictures"), new String[]{"JPG", "JPEG", "TIF", "TIFF", "jpg", "jpeg", "tif", "tiff"}, true));
//Use this to map file name to file
Map<String, File> map = new HashMap();
//Use this to add data to the map
IMAGE_COLLECTION.forEach((file) -> {map.put(file.getName().substring(0, file.getName().lastIndexOf(".")).toLowerCase(), file);});
for (Row row: sheet1)
{
//extracted data from excel
String FILENAME = row.getCell(0,Row.MissingCellPolicy.CREATE_NULL_AS_BLANK).getStringCellValue();
//If the map contains the file name, create `DetailedData` object. Then set data. Then add object to datacollection list.
if (map.containsKey(FILENAME.toLowerCase()))
{
DetailedData data = new DetailedData();
data.setFileName(FILENAME);
data.setFullPath(map.get(FILENAME.toLowerCase()).getAbsolutePath());
dataCollection.add(data);
}
}
Comments in the code
I still believe this could be cleaned up a little more if you used List<File> dataCollection = new ArrayList()

Answer 2

If you really want to speed up your search, you should try not to do things repeatedly which could just be done once. For example you could use two loops. The first to prepare your search and the second to actually do the search. Inside your filter you call FilenameUtils.getBaseName and two time a conversion to lower case. It would be better to do these things only once in the first loop and store the resulting Strings in a list. In the second loop you then do the search on this list.
I am also wondering why you use ObservableLists here. A simple List would do as well.

Answer 3

I've tested another approach in this slow iteration.
It seems that the cause is declaring the Stream repeatedly inside the foreach.
I tried using Baeldung's solution <Supplier> and declared it outside the loop together with parallelStream()
Sample Code:
Supplier<Stream<File>> streamSupplier = () -> imageCollection.parallelStream();
for (Row row : sheet)
{
File IMAGE = streamSupplier.get().filter(e -> FilenameUtils.getBaseName(e.getName()).toLowerCase().equals(FILENAME.toLowerCase())).findFirst().orElse(null);
if (IMAGE != null)
IMAGE_SOURCE = IMAGE.getAbsolutePath();
}
Result went 45000ms
Please correct me if my approach was not right.