打印機有黑白的，有彩色的，學校都有打印機，用於打印，現在用多態來描述

package jiCheng_duoTai;

//public class DaYinJi {
//  public static void main(String[] args) {
//    School s = new School();
//    BlackPrinter bp = new BlackPrinter("惠普牌");
//    ColorPrinter cp = new ColorPrinter("三星牌");
//    s.usePrinter(bp,"武漢大學");//打印的內容
//    s.usePrinter(cp,"軟件技術二班");//打印的內容
//  }
//}
class Printer{//父類，打印機
 private String brand;


public Printer() {}
 public Printer(String brand) {
  this.brand = brand;
 }
 public void print(String content) {
  System.out.println(content);
 }
 public String getBrand() {
  return brand;
 }
 public void setBrand(String brand) {
  this.brand = brand;
 }
}
class BlackPrinter extends Printer {//子類，黑白打印機
 public BlackPrinter() {
  super();
 }
 public BlackPrinter(String brand) {
  super(brand);
 }
 public void print (String content) {
  System.out.println(getBrand()+"黑白打印機："+content);
 }
}
class ColorPrinter extends Printer{//子類，彩色打印機
 public ColorPrinter() {
  super();
 }
 public ColorPrinter(String brand) {
  super(brand);
 }
 public void print (String content) {
  System.out.println(getBrand()+"彩色打印機："+content);
  }
}
//class School{
// public void usePrinter(BlackPrinter bp,String content) {
//  bp.print(content);
// }
//  public void usePrinter(ColorPrinter cp,String content) {
//  cp.print(content);
// }
//}



//首先，上面的代碼未使用到多態的形式，如果打印機的品牌很多，上面的代碼就不適用了，所以進行改進，改爲多態形式
//首先將上面的School類進行註釋，進行新的編寫
class School{
 public void usePrinter(Printer p,String content) {
  p.print(content);
 }
}
//其次，將main函數代碼塊進行註釋，進行重新的編寫，進而實現多態
public class DaYinJi {
 public static void main(String[] args) {
   School s = new School();
   Printer p1=new BlackPrinter("惠普牌");
   Printer p2=new ColorPrinter("三星牌");
   s.usePrinter(p1,"武漢大學");
   s.usePrinter(p2,"軟件技術專業");
 }
}
//對於上面的代碼也可以改用下面的這個形式
//School s = new School();
//BlackPrinter bp = new BlackPrinter("惠普牌");
//ColorPrinter cp = new ColorPrinter("三星牌");
//s.usePrinter(bp,"武漢大學");//父類引用指向子類對象  p=bp;
//s.usePrinter(cp,"軟件技術二班");