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Java example source code file (FileLabelAwareIterator.java)

This example Java source code file (FileLabelAwareIterator.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

arraylist, atomicinteger, bufferedreader, builder, exception, file, filelabelawareiterator, labelleddocument, labelssource, list, override, runtimeexception, string, stringbuilder, util

The FileLabelAwareIterator.java Java example source code

package org.deeplearning4j.text.documentiterator;

import lombok.NonNull;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;

 * This is simple filesystem-based LabelAware iterator.
 * It assumes that you have one or more folders organized in the following way:
 * 1st level subfolder: label name
 * 2nd level: bunch of documents for that label
 * You can have as many label folders as you want, as well.
 * @author raver119@gmail.com
public class FileLabelAwareIterator implements LabelAwareIterator {
    protected List<File> files;
    protected AtomicInteger position = new AtomicInteger(0);
    protected LabelsSource labelsSource;

        Please keep this method protected, it's used in tests
    protected FileLabelAwareIterator() {


    protected FileLabelAwareIterator(@NonNull List<File> files, @NonNull LabelsSource source) {
        this.files = files;
        this.labelsSource = source;

    public boolean hasNextDocument() {
        return position.get() < files.size();

    public LabelledDocument nextDocument() {
        File fileToRead = files.get(position.getAndIncrement());
        String label = fileToRead.getParentFile().getName();
        try {
            LabelledDocument document = new LabelledDocument();
            BufferedReader reader = new BufferedReader(new FileReader(fileToRead));
            StringBuilder builder = new StringBuilder();
            String line = "";
            while ((line = reader.readLine()) != null) builder.append(line).append(" ");


            try {
            } catch (Exception e) {
                throw new RuntimeException(e);

            return document;
        } catch (Exception e) {
            throw new RuntimeException(e);

    public void reset() {

    public LabelsSource getLabelsSource() {
        return labelsSource;

    public static class Builder {
        protected List<File> foldersToScan = new ArrayList<>();

        public Builder() {


         * Root folder for labels -> documents.
         * Each subfolder name will be presented as label, and contents of this folder will be represented as LabelledDocument, with label attached
         * @param folder folder to be scanned for labels and files
         * @return
        public Builder addSourceFolder(@NonNull File folder) {
            return this;

        public FileLabelAwareIterator build() {
            // search for all files in all folders provided
            List<File> fileList = new ArrayList<>();
            List<String> labels = new ArrayList<>();

            for (File file: foldersToScan) {
                if (!file.isDirectory()) continue;

                File[] files = file.listFiles();
                if (files == null || files.length ==0 ) continue;

                for (File fileLabel: files) {
                    if (!fileLabel.isDirectory()) continue;

                    if (!labels.contains(fileLabel.getName())) labels.add(fileLabel.getName());

                    File[] docs = fileLabel.listFiles();
                    if (docs == null || docs.length == 0) continue;

                    for (File fileDoc: docs) {
                        if (!fileDoc.isDirectory()) fileList.add(fileDoc);
            LabelsSource source = new LabelsSource(labels);
            FileLabelAwareIterator iterator = new FileLabelAwareIterator(fileList, source);

            return iterator;

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