创建了5辆车，我觉得条例还算清晰，应该好懂。。。欢迎大家来指正，讨论

//一共创建了5辆车。。写的应该还算有条理，比较容易懂
//其中cc是载货量，pc是载人量，pr是租一天的价格
package project3.rentcars;
/**/define superclass**
public abstract class Carrent {
    public int cc;
    public int pc;
    public int pr;
    public abstract void descrip();
//get method，（get太长了，我用的m代替）
    public abstract int mcc();
    public abstract int mpc();
    public abstract int mpr();
    //public abstract void set(/*int cc,int pc,int pr*/);
    //public abstract int mpr();
    /*the method set is no necessary（我觉得并不要用set方法，用了反而后面重写的时候麻烦,我没有用private修饰变量，这样可能不太安全。。）*/
    }
//subclass truck1
public class Truck1 extends Carrent {
    public int mcc(){
        int cc=5;
        return cc;
        }
    public int mpc(){
        int pc=0;
        return pc;
    }
    public int mpr(){
        int pr=100;
        return pr;
    };

    @Override
    public void descrip() {
        // TODO Auto-generated method stub
        System.out.println("truck1:");
        System.out.println("cargo capality:"+mcc()+"T");
        System.out.println("person capality:"+mpc());
        System.out.println("rental:"+mpr()+"$ for one day"); 
    }

}
//subclass truck2
public class Truck2 extends Carrent {

    public int mcc(){
        int cc=10;
        return cc;
        }
    public int mpc(){
        int pc=0;
        return pc;
    }
    public int mpr(){
        int pr=200;
        return pr;
    };  @Override
    public void descrip() {
        // TODO Auto-generated method stub
        System.out.println("truck2:");
        System.out.println("cargo capality:"+mcc()+"T");
        System.out.println("person capality:"+mpc());
        System.out.println("rental:"+mpr()+"$ for one day"); 

    }

}
//subclass bus1
public class Bus1 extends Carrent {
    int cc=0;
    int pc=10;
    int pr=150;
    public int mcc(){
        return cc;
    }
    public int mpc(){
        return pc;
    }
    public int mpr(){
        return pr;
    };
    @Override
    public void descrip() {
        // TODO Auto-generated method stub
        System.out.println("bus1:");
        System.out.println("cargo capality:"+mcc()+"T");
        System.out.println("person capality:"+mpc());
        System.out.println("rental:"+mpr()+"$ for one day"); 
    }

}
//subclass bus2
public class Bus2 extends Carrent {

    public int mcc(){
        int cc=0;
        return cc;
        }
    public int mpc(){
        int pc=15;
        return pc;
    }
    public int mpr(){
        int pr=250;
        return pr;
    };  @Override
    public void descrip() {
        // TODO Auto-generated method stub
        System.out.println("bus2:");
        System.out.println("cargo capality:"+mcc()+"T");
        System.out.println("person capality:"+mpc());
        System.out.println("rental:"+mpr()+"$ for one day"); 
    }

}
//subclass pick
public class Pick extends Carrent {

    public int mcc(){
        int cc=10;
        return cc;
        }
    public int mpc(){
        int pc=15;
        return pc;
    }
    public int mpr(){
        int pr=300;
        return pr;
    };  @Override
    public void descrip() {
        // TODO Auto-generated method stub
        System.out.println("pick:");
        System.out.println("cargo capality:"+mcc()+"T");
        System.out.println("person capality:"+mpc());
        System.out.println("rental:"+mpr()+"$ for one day"); 
    }

}
// main method
import java.util.Scanner;
public class Test {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        //define some useful variables
        int num;
        int numt1;
        int numt2;
        int numb1;
        int numb2;
        int numpi;
        int loadsum;
        int persum;
        int rentsum;
        System.out.println("do you want to rent cars? ");
        System.out.println("1.yes  2.no");
        System.out.println("please input 1or2");
        Scanner input=new Scanner(System.in);
        num=input.nextInt();
        //if you want rent cars(input num 1),用了一个选择结构
        if(num==1){
            //the description of cars
            System.out.println("the cars description");
            //polymorphism    define some pointers point to the subobjects
            Carrent t1=new Truck1();
            Carrent t2=new Truck2();
            Carrent b1=new Bus1();
            Carrent b2=new Bus2();
            Carrent pi=new Pick();
            /*the code above can changed into another way like:Carrent car[]={new Truck1,new Truck2...}*/
            t1.descrip();
            t2.descrip();
            b1.descrip();
            b2.descrip();
            pi.descrip();
            //asking for car renting
            System.out.println("how many t1 do you want rent?");
            numt1=input.nextInt();
            System.out.println("how many t2 do you want rent?");
            numt2=input.nextInt();
            System.out.println("how many b1 do you want rent?");
            numb1=input.nextInt();
            System.out.println("how many b2 do you wnat rent?");
            numb2=input.nextInt();
            System.out.println("how many pi do you wnat rent?");
            numpi=input.nextInt();
            //print your renting information
            System.out.println("your information:");
            System.out.println("you have rent");
            System.out.println(+numt1 +"  t1");
            System.out.println(numt2 +"  t2");
            System.out.println(numb1 +"  b1");
            System.out.println(numb2 +"  b2");
            System.out.println(numpi +"  pi");
            loadsum=t1.mcc()*numt1+t2.mcc()*numt2+b1.mcc()*numb1+b2.mcc()*numb2+pi.mcc()*numpi;
            persum=t1.mpc()*numt1+t2.mpc()*numt2+b1.mpc()*numb1+b2.mpc()*numb2+pi.mpc()*numpi;
            rentsum=t1.mpr()*numt1+t2.mpr()*numt2+b1.mpr()*numb1+b2.mpr()*numb2+pi.mpr()*numpi;
            System.out.println("the total load:"+loadsum+"T");
            System.out.println("the total person volume:"+persum);
            System.out.println("the total rental:"+rentsum+"$");
            System.out.println("thanks for your patronage!");

        }
        else{
            System.out.println("fuck you bitch! go away if you dont rent cars!");
        }

    }

}