想问问这个抽象类怎么用呀

Question

对抽象类理解的还不是很透彻，想问问这个抽象类怎么用呀，谢谢了

Answer 1

public abstract class Printer {
private  String brand;
public Printer(String brand) {
  super();
  this.brand = brand;
  }
  public String getBrand() {
  return brand;
  }
  public void setBrand(String brand) {
  this.brand = brand;
  }
  public abstract void print(String file);  //抽象方法
  }

public class BlackPrinter extends Printer {
public BlackPrinter(String brand) {
  super(brand);
  // TODO Auto-generated constructor stub
  }
  @Override
 public void print(String file) {
 // TODO Auto-generated method stub
  System.out.println(getBrand()+"打印机正在黑白打印"+file);
  }}

public class ColorPrinter extends Printer {
public ColorPrinter(String brand) {
super(brand);
  // TODO Auto-generated constructor stub
  }
  @Override
 public void print(String file) {
  // TODO Auto-generated method stub
  System.out.println(getBrand()+"打印机正在彩色打印"+file);
  }}

public class PrinterTest {
public static void printFile(Printer p,String file) {
p.print(file);
}
public static void main(String[] args) {
Printer blackPrinter=new BlackPrinter("惠普牌");
  printFile(blackPrinter, "简历");

Printer colorPrinter=new ColorPrinter("佳能牌");
  printFile(colorPrinter, "简历");
  }}