public abstract class AbstractFile {
    protected String name;
    public AbstractFile(String name) {
        this.name = name;
    }
    /**
     * 輸入文件名;包含節(jié)點(diǎn)下的子節(jié)點(diǎn)
     */
    public abstract void display();
    /**
     * 添加文件
     * @param file
     */
    public abstract void add(AbstractFile file);
    /**
     * 刪除文件
     * @param file
     */
    public abstract void remove(AbstractFile file);
}

public class File extends AbstractFile {
    public File(String name) {
        super(name);
    }
    /**
     * 輸入文件名;包含節(jié)點(diǎn)下的子節(jié)點(diǎn)
     */
    @Override
    public void display() {
        System.out.println("這是文件:" + name);
    }
    /**
     * 添加文件
     *
     * @param file
     */
    @Override
    public void add(AbstractFile file) {
        throw new UnsupportedOperationException("文件不支持添加操作");
    }
    /**
     * 刪除文件
     *
     * @param file
     */
    @Override
    public void remove(AbstractFile file) {
        throw new UnsupportedOperationException("文件不支持刪除操作");
    }
}

public class Directory extends AbstractFile {
    private List<AbstractFile> fileList = new ArrayList<>();
    public Directory(String name) {
        super(name);
    }
    @Override
    public void add(AbstractFile file) {
        fileList.add(file);
    }
    @Override
    public void remove(AbstractFile file) {
        fileList.remove(file);
    }
    /**
     * 輸入文件名;包含節(jié)點(diǎn)下的子節(jié)點(diǎn)
     */
    @Override
    public void display() {
        System.out.println("這是目錄:" + name);
        fileList.forEach(AbstractFile::display);
    }
}

public class Demo {
    public static void main(String[] args) {
        AbstractFile root = new Directory("根目錄");
        AbstractFile file1 = new File("文件1");
        AbstractFile file2 = new File("文件2");
        AbstractFile file3 = new File("文件3");
        AbstractFile file4 = new File("文件4");
        AbstractFile directory1 = new Directory("目錄1");
        AbstractFile directory2 = new Directory("目錄2");
        directory1.add(file1);
        directory1.add(file2);
        directory1.add(directory2);
        directory2.add(file3);
        directory2.add(file4);
        root.add(directory1);
        root.display();
    }
}