homebuilder.java

来自「orcale9i-java-programming外文书籍源码,结合orcale」· Java 代码 · 共 25 行

public class HomeBuilder {
  public static void main(String arg[]) {
    ThreeBedroomHouse myHouse1 = new ThreeBedroomHouse();

    // This is legal.
    myHouse1.cleanThirdBedroom();

    House myHouse2 = new ThreeBedroomHouse();

    // This is not legal. It will generate an error
    // at compile time.
    myHouse2.cleanThirdBedroom();

    // But we could cast myHouse2 to a ThreeBedroomHouse:
    ThreeBedroomHouse myHouse3 = (ThreeBedroomHouse) myHouse2;

    // So this would be legal:
    myHouse3.cleanThirdBedroom();

    // Or we could do the casting above in one line
    // without using an extra variable
    ((ThreeBedroomHouse) myHouse2).cleanThirdBedroom();
  } 
}