hackjutsu

public interface Command {
  void execute();
  void undo();
}

hackjutsu

public class ReceiverB {
  public void doAction() {
    System.out.println("ReceiverB do action!!");
  }
  
  public void undoAction() {
    System.out.println("ReceiverB undo action!!");
  }
}

hackjutsu

public class ReceiverA {
  public void doAction() {
  	System.out.println("ReceiverA do action!!");
  }
  
  public void undoAction() {
  	System.out.println("ReceiverA undo action!!");
  }
}

hackjutsu

public class DemoMain {
  public static void main(String[] args) {
    Employee emp1 = new Developer("John", 10000);
    Employee emp2 = new Developer("David", 15000);
    
    Employee manager1 = new Manager("Daniel", 25000);
    manager1.add(emp1);
    manager1.add(emp2);
    
    Employee emp3 = new Developer("Michael", 20000);

hackjutsu

public class Developer implements Employee {
  private String name;
  private double salary;
  
  public Developer(String name, double salary) {
    this.name = name;
    this.salary = salary;
  }
  public void add(Employee employee) {
    // Intentionally left blank

hackjutsu

public class Manager implements Employee {
  private String name;
  private double salary;
  private List<Employee> employees = new ArrayList<Employee>();
  
  public Manager(String name, double salary) {
    this.name = name;
    this.salary = salary;
  }
 

hackjutsu

public interface Employee {
  void add(Employee employee);
  void remove(Employee employee);
  Employee getChild(int i);
  String getName();
  double getSalary();
  void print();
}

hackjutsu

public class ClientMain {
  public static void main(String[] args) {
    PetRepository pets = new PetRepository();
    for (Iterator iter = pets.getIterator(); iter.hasNext(); ) {
      String name = (String) iter.next();
      System.out.println(name);
    }
  }
}

hackjutsu

public class PetRepository implements Container {
  private class NameIterator implements Iterator {
    int index = 0;

    @Override
    public boolean hasNext() {
      return index < pets.length;
    }

    @Override

hackjutsu

public interface Iterator {
  boolean hasNext();
  Object next();
}

public interface Container {
  Iterator getIterator();
}