public abstract class FolderComponent {
 private String name;

 public String getName() {
 return name;
 }

 public void setName(final String name) {
 this.name = name;
 }

 public FolderComponent() {
 }

 public FolderComponent(final String name) {
 this.name = name;
 }

 public abstract void add(FolderComponent component);

 public abstract void remove(FolderComponent component);

 public abstract void display();
}

public class FileLeaf extends FolderComponent {
 public FileLeaf(final String name) {
 super(name);
 }

 @Override
 public void add(final FolderComponent component) {
 // ...
 }

 @Override
 public void remove(final FolderComponent component) {
 // ...
 }

 @Override
 public void display() {
 System.out.println("FileLeaf:" + this.getName());
 }
}

public class FolderComposite extends FolderComponent {
 private final List<FolderComponent> components;

 public FolderComposite(final String name) {
 super(name);
 this.components = new ArrayList<FolderComponent>();
 }

 public FolderComposite() {
 this.components = new ArrayList<FolderComponent>();
 }

 @Override
 public void add(final FolderComponent component) {
 this.components.add(component);
 }

 @Override
 public void remove(final FolderComponent component) {
 this.components.remove(component);
 }

 @Override
 public void display() {
 System.out.println("FolderComposite---name:" + this.getName());
 for (final FolderComponent component : components) {
  System.out.println("FolderComposite---component-name:" + component.getName());
 }
 }
}

public class Client
{
 public static void main(final String[] args)
 {
  final FolderComponent leaf = new FileLeaf("runnable file");
  leaf.display();

  final FolderComponent folder = new FolderComposite("new folder");
  folder.add(new FileLeaf("content1 in new folder"));
  folder.add(new FileLeaf("content2 in new folder"));
  folder.display();
 }
}