Head First Java - 7장 상속과 다형성, TestBoats.java

class Boat {
 
 private int length;
 
 public void setLength(int len) {
  length = len;
 }

 public int getLength() {
  return length;
 }

 public void move() {
  System.out.print("drif ");
 }
}

class Rowboat extends Boat {
 
 public void rowTheBoat() {
  System.out.println("stroke natasha");
 }
}

class Sailboat extends Boat {
 public void move() {
  System.out.println("hoist sail ");
 }
}

public class TestBoats {
 
 public static void main(String[] args) {
  Boat b1 = new Boat();
  Sailboat b2 = new Sailboat();
  Rowboat b3  = new Rowboat();

  b2.setLength(32);
  b1.move(); 
  b3.move();
  b2.move();
 }
};