TreeFolderPure<T> - main implementation of the tree building algorithm.

public TreeFolderPure(PreparedFolders<Map<String, Folder<T>>> prepFolders)

Map<String, Folder<T>>> prepFolders - prepared folders map.

public TreeFolderPure(
            FoldersFile<String, String> foldersFile,
            PreparedFolders<Map<String, Folder<T>>> prepFolders)


FoldersFile<String, String> foldersFile - folders name of file (default - FoldersFileName);
Map<String, Folder<T>>> prepFolders - prepared folders map.

List<String> rawFiles = new ArrayList<>();
rawFiles.add("/root1.txt");
rawFiles.add("/root2.txt");
rawFiles.add("/root3.txt");
rawFiles.add("/folder1/file1.txt");
rawFiles.add("/folder1/file2.txt");
rawFiles.add("/folder2/file1.txt");

PreparedFolders<Map<String, Folder<String>>> prepFolders = new PreparedFoldersMapText(
                new PreparedFoldersMapRaw(rawFiles));

TreeFolder<String> trFolder = new TreeFolderPure<>(
        new FoldersFileName(),
        prepFolders);

Folder<String> root = trFolder.grow();
root.travel(folder -> {
    System.out.println(folder.fullName()); 
    folder.files().forEach(file -> System.out.println("\t" + file));
});