Question

JAVA求大神帮忙看看怎么弄？

import java.util.Scanner;

public class shengji {
/**
* @param args
*/
public static void main(String[] args) {
Scanner input=new Scanner(System.in);
while(true){
System.out.println("请选择购买的商品编号:1.T恤2.网球鞋3.网球拍");
int num=input.nextInt();
System.out.println("请选择购买数量:");
int b=input.nextInt();

switch (num) {
case 1:
double money1=245.0;
System.out.println("T恤￥"+money1+"\t"+"数量:"+b+"\t"+"合计:"+money1*b);
break;
case 2:
double money2=570.0;

System.out.println("网球鞋￥"+money2+"\t"+"数量:"+b+"\t"+"合计:"+money2*b);
break;
case 3:
double money3=1000.0;

System.out.println("网球拍￥"+money3+"\t"+"数量:"+b+"\t"+"合计:"+money3*b);
break;

default:
System.out.println("选择错误，重新选择");
break;
}
System.out.println("是否继续y/n");
String str=input.next();

if(str.equals("n")){

System.out.println("折扣:0.8");
System.out.println("应付金额:");
System.out.println("实付金额:");
int Smoney=input.nextInt();
System.out.println("找钱:"+Smoney);
}
}

}
}
应付金额应该怎么写？

Answer 1

定义一个sum,在每个case语句后面赋值, ,然后sum=sum*0.8 ，最后引用就可以了
import java.util.Scanner;

public class shengji {
/**
* @param args
*/

public static void main(String[] args) {
Scanner input=new Scanner(System.in);
double sum=0;
while(true){
System.out.println("请选择购买的商品编号:1.T恤2.网球鞋3.网球拍");
int num=input.nextInt();
System.out.println("请选择购买数量:");
int b=input.nextInt();

switch (num) {
case 1:
double money1=245.0;
sum=money1*b;
System.out.println("T恤￥"+money1+"\t"+"数量:"+b+"\t"+"合计:"+sum);
break;
case 2:
double money2=570.0;
sum=money2*b;
System.out.println("网球鞋￥"+money2+"\t"+"数量:"+b+"\t"+"合计:"+sum);
break;
case 3:
double money3=1000.0;
sum=money3*b;
System.out.println("网球拍￥"+money3+"\t"+"数量:"+b+"\t"+"合计:"+sum);
break;

default:
System.out.println("选择错误，重新选择");
break;
}
System.out.println("是否继续y/n");
String str=input.next();

if(str.equals("n")){

System.out.println("折扣:0.8");
sum=sum*0.8;
System.out.println("应付金额:"+sum);
System.out.println("实付金额:");
int Smoney=input.nextInt();
System.out.println("找钱:"+Smoney);
}
}

}
}

追问

这样sum下会有红线，会报错