public class Agenda{

   private ArrayList<Task> tasks = new ArrayList<Task>();


   public void addTask(String name, int priority, String description){
      Task t = new Task(name, priority, description);
      tasks.add(t);
   }

   ....
}

public class Task{

  private String name;
  private int priority;
  String description;

  public Task(String name, int priority, String description){
    this.name = name;
    this.priority = priority;
    this.description = description;
  }

  ...
}

....