Random file paths to file tree structure using java

FilePathsToJsonTree.java

import java.util.*;

public class FilePathsToJsonTree {

    public static void main(final String... args) {

        List<String> filePaths = new ArrayList<>();
        filePaths.add("root/a/1.txt");
        filePaths.add("root/");
        filePaths.add("root/a/");
        filePaths.add("root/a/b/");
        filePaths.add("root/e/d/4.txt");
        filePaths.add("root/a/3.txt");
        filePaths.add("root/b/c/");
        filePaths.add("root/b/c/5.5xt");
        filePaths.add("root/e/d/");
        final dirNode directoryRootNode = createDirectoryTree(filePaths);

        System.out.println(directoryRootNode);

    }



    public static dirNode createDirectoryTree(final List<String> list) {
        dirNode treeRootNode = null;
        for (final String rawPath : list) {
            final String path = rawPath.startsWith("/") ? rawPath.substring(1) : rawPath;
            final String[] pathElements = path.split("/");
            dirNode movingNode = null;
            for (final String pathElement : pathElements) {

                String fileExtension = getFileExtension(pathElement);
                boolean isDir = false;

                movingNode = new dirNode(movingNode, pathElement, fileExtension);
            }

            if (treeRootNode == null) {
                treeRootNode = movingNode.getRoot();
            } else {
                treeRootNode.merge(movingNode.getRoot());
            }
        }

        return treeRootNode;
    }

    public static String getFileExtension(String fileName) {
        int lastIndexOf = fileName.lastIndexOf(".");
        if (lastIndexOf == -1) {
            return "";
        }
        return fileName.substring(lastIndexOf);
    }

    private static class dirNode {

        private final Set<dirNode> childFiles = new LinkedHashSet<>();

        private final String value;
        private final String fileExt;

        private final dirNode parent;

        public dirNode(final dirNode parent, final String value, final String fileExt) {
            this.parent = parent;
            if (this.parent != null) {
                this.parent.childFiles.add(this);
            }

            this.value = value;
            this.fileExt = fileExt;
        }

        public Set<dirNode> getchildFiles() {
            return this.childFiles;
        }

        public String getValue() {
            return this.value;
        }

        public String getFileExt() {
            return this.fileExt;
        }


        public dirNode getParent() {
            return this.parent;
        }

        public int getChildCount() {
            int childCount = this.isChild() ? 1 : 0;
            for (final dirNode child : this.childFiles) {
                childCount += child.getChildCount();
            }

            return childCount;
        }

        public boolean isChild() {
            return this.childFiles.isEmpty();
        }

        public dirNode getRoot() {
            return this.parent == null ? this : this.parent.getRoot();
        }

        public void merge(final dirNode that) {
            if (!this.value.equals(that.value)) {
                return;
            } else if (this.childFiles.isEmpty()) {
                this.childFiles.addAll(that.childFiles);
                return;
            }

            final dirNode[] thischildFiles = this.childFiles
                    .toArray(new dirNode[this.childFiles.size()]);
            for (final dirNode thisChild : thischildFiles) {
                for (final dirNode thatChild : that.childFiles) {
                    if (thisChild.value.equals(thatChild.value)) {
                        thisChild.merge(thatChild);
                    } else if (!this.childFiles.contains(thatChild)) {
                        this.childFiles.add(thatChild);
                    }
                }
            }
        }

        @Override
        public boolean equals(final Object o) {
            if (this == o) {
                return true;
            }
            if (o == null || getClass() != o.getClass()) {
                return false;
            }
            final dirNode that = (dirNode) o;
            return Objects.equals(this.value, that.value)
                    && Objects.equals(this.parent, that.parent);
        }

        @Override
        public int hashCode() {
            return Objects.hash(this.value, this.parent);
        }


        @Override
        public String toString() {
            return "{" +
                    "\"name\":\"" + this.value + '\"' +
                    ", \"ext\":\"" + this.fileExt + '\"' +
                    ", \"childFiles\":" + this.childFiles +
                    '}';
        }
    }
}