使用复合模式的文件系统

Question

我正在尝试构建一个包含以下类的文件系统：FileSystem、Directory、File。

我的代码是：

public class FileSystem {
    private List<Directory> ld;
    public FileSystem() {
        ld = new ArrayList<Directory>();
    }
    public void addDirectory(Directory dir) {
        ld.add(dir);
    }
    public void showAll() {
        for (Directory directory : ld) {
            directory.showAll();
        }
    }
}

public class File {
    private String fileName;

    public File(String fileName) {
        this.fileName = fileName;
    }
    public String getName() {
        return fileName;
    }
    public void setName(String name) {
        this.fileName = fileName;
    }
}

public class Directory {
    private String directoryName;
    private List<File> files;
    private List<Directory> subDirs;

    public Directory(String directoryName) {
        this.directoryName = directoryName;
        files = new ArrayList<File>();
        subDirs = new ArrayList<Directory>();
    }
    public String getName() {
        return this.directoryName;
    }
    public void setName(String name) {
        this.directoryName = name;
    }
    // Add and remove files
    public void addFile(File file) {
        files.add(file);
    }
    public void removeFile(File file) {
        files.remove(file);
    }
    // Add and remove directories
    public void addDirectory(Directory dir) {
        subDirs.add(dir);
    }
    public void removeDirectory(Directory dir) {
        subDirs.remove(dir);
    }

    public void showAll() {
        System.out.println(this.directoryName);
        for (File f : files) {
            System.out.println("    " + f.getName());
        }
    }
}

public class Create {
    public static void main(String[] args) {
        FileSystem fs = new FileSystem();
        Directory d1 = new Directory("Directory1");

        d1.addFile(new File("FileX"));
        Directory d11 = new Directory("Directory11");
        d11.addFile(new File("File1"));
        d11.addFile(new File("File2"));
        d1.addDirectory(d11);

        fs.addDirectory(d1);
        fs.showAll();
    }
}  

但是，当我试图使用showAll方法打印所有内容时，它只打印'Directory1‘和'FileX'，但我想打印：

Directory1

FileX

Directory11

File1

File2

Answer 1

您的Directory#showAll应该如下所示：

public void showAll() {
    System.out.println(this.directoryName);
    for (File f : files) {
        System.out.println("    " + f.getName());
    }
    for(Directory subDir: subDirs){
        subDir.showAll();
    }
}

因此，它也递归地遍历subDirs。

ps.s.-我也会去除FileSystem实体，或者至少引入Directory和FileSystem之间的父子关系。