Java Tutorial/Design Pattern/Factory Pattern

A simple static factory method.

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
abstract class Shape {
  public abstract void draw();
  public abstract void erase();
  public static Shape factory(String type) {
    if (type.equals("Circle"))
      return new Circle();
    if (type.equals("Square"))
      return new Square();
    throw new RuntimeException("Bad shape creation: " + type);
  }
}
class Circle extends Shape {
  Circle() {
  } // Package-access constructor
  public void draw() {
    System.out.println("Circle.draw");
  }
  public void erase() {
    System.out.println("Circle.erase");
  }
}
class Square extends Shape {
  Square() {
  } // Package-access constructor
  public void draw() {
    System.out.println("Square.draw");
  }
  public void erase() {
    System.out.println("Square.erase");
  }
}
public class ShapeFactory {
  public static void main(String args[]) {
    List<Shape> shapes = new ArrayList<Shape>();
    Iterator it = Arrays.asList(
        new String[] { "Circle", "Square", "Square", "Circle", "Circle", "Square" }).iterator();
    while (it.hasNext())
      shapes.add(Shape.factory((String) it.next()));
    it = shapes.iterator();
    
    while (it.hasNext()) {
      Shape s = (Shape) it.next();
      s.draw();
      s.erase();
    }
  }
}

Creating and Extending Objects with the Factory Patterns

public class MainClass {
  public static void main(String args[]) {
    SecureFactory factory;
    factory = new SecureFactory();
    Connection connection = factory.createConnection("Oracle");
    System.out.println("You"re connecting with " + connection.description());
  }
}
class SecureFactory extends ConnectionFactory {
  public Connection createConnection(String type) {
    if (type.equals("Oracle")) {
      return new SecureOracleConnection();
    } else if (type.equals("SQL Server")) {
      return new SecureSqlServerConnection();
    } else {
      return new SecureMySqlConnection();
    }
  }
}
abstract class Connection {
  public Connection() {
  }
  public String description() {
    return "Generic";
  }
}
abstract class ConnectionFactory {
  public ConnectionFactory() {
  }
  protected abstract Connection createConnection(String type);
}
class SqlServerConnection extends Connection {
  public SqlServerConnection() {
  }
  public String description() {
    return "SQL Server";
  }
}
class SecureSqlServerConnection extends Connection {
  public SecureSqlServerConnection() {
  }
  public String description() {
    return "SQL Server secure";
  }
}
class SecureOracleConnection extends Connection {
  public SecureOracleConnection() {
  }
  public String description() {
    return "Oracle secure";
  }
}
class SecureMySqlConnection extends Connection {
  public SecureMySqlConnection() {
  }
  public String description() {
    return "MySQL secure";
  }
}