做项目要的就是最少的代码实现最多的功能，而且用最简单的知识来实现它。
-------玄鉴
//父类----车，省略了，get/set方法。
public class Che {
private String name;private int daymoney;private int day;public void show() {System.out.print("\t"+this.name+ "\t"+this.daymoney+"元/天\t");}}　　//子类——客车.省略了，get/set方法。
public class Car extends Che {
private int personNum;Car(String name, int daymoney,int personNum) { super(name, daymoney); this.personNum=personNum;}@Overridepublic void show() { //super.show(); System.out.print("\t"+this.getName()+ "\t"+this.getDaymoney()+"元/天\t"); System.out.print("载人："+personNum+"人");}　　————————————————————
//子类——货车 省略了，get/set方法。
　　public class Bus extends Che {
private int cargoNum;Bus(String name, int daymoney,int cargoNum) { super(name, daymoney); this.cargoNum=cargoNum;}@Overridepublic void show() { super.show(); System.out.print("载货："+cargoNum+"吨");}　　}
　　//子类——载货载人两用车。 省略了，get/set方法。
public class Pika extends Che {
private int personNum;private int cargoNum;Pika(String name, int daymoney,int personNum,int cargoNum) { super(name, daymoney); this.personNum=personNum; this.cargoNum=cargoNum;}@Overridepublic void show() { super.show(); System.out.print("载货："+cargoNum+"吨"+ "载人："+personNum+"人");}　　————————————————————
//流程测试类
　　import java.util.Scanner;
　　public class Liucheng {
public static void main(String[] args) { System.out.println("欢迎使用租车系统"); System.out.println("您是否要租车（1.是 2.否）"); Scanner in = new Scanner(System.in); Che[] ches = { new Car("奥迪A4", 500, 4), new Car("马自达", 400, 4), new Pika("皮卡雪6", 450, 4, 2), new Bus("金龙", 800, 20), new Bus("松花江", 400, 4), new Bus("依维柯", 1000, 20) }; if (in.nextInt() == 1) { System.out.println("序号" + "\t汽车名称" + "\t租金" + "\t容量"); for (int i = 0; i < ches.length; i++) { System.out.print(i); ches[i].show(); System.out.println(""); } }else{ System.out.println("程序退出。"); return; } System.out.println("请问你要租车的数量："); int a = in.nextInt(); int sum = 0; int d = 0; for (int i = 0; i < a; i++) { System.out.println("请问你租赁的第" + (i + 1) + "辆车的序号是："); int b = in.nextInt();　　if (b>=0&&b<6) {
System.out.println("请问你要租的天数：");
int c = in.nextInt();
ches[b].setDay(c);
d = ches[b].getDaymoney() * ches[b].getDay();
sum = sum + d; System.out.println("第" + (i + 1) + "辆车" + ches[b].getName() + "的价钱为：" + d); }else { System.out.println("输入有误，请重新输入"); continue;　　}
}
System.out.println("总价钱为：" + sum);
}
}