Java程序无法运行

Question

我的java程序无法正确计算折扣，我不明白为什么。我是java新手，不知道如何解决这个问题，所以任何帮助将不胜感激。例如，如果您购买 100 个包，您的折扣应该是 82.50，但我的说是 27.50

import java.text.DecimalFormat;
import java.util.Scanner;
public class Coffee {
    public static void main(String args[]){
        Scanner bags = new Scanner(System.in);
        System.out.println("Hello and welcome to the program");
        System.out.println("Here is the discount list for the IT125 Coffee Company");
        System.out.println("<= 24 Bags      No discount");
        System.out.println(">= 25 Bags      5% ");
        System.out.println(">= 50 Bags      10% ");
        System.out.println(">= 100 Bags     15% ");
        System.out.println(">= 150 Bags     20% ");
        System.out.println(">= 200 Bags     25% ");
        System.out.println(">= 300 Bags     30% ");
        System.out.println("");

        DecimalFormat df = new DecimalFormat("0.00");
        int num1;
        System.out.print("Enter the number of bags purchased: ");
        num1 = bags.nextInt();
        System.out.println("Bags purchased " + num1);
        double cost, disc, totcost;
        totcost = 0;
        disc = 0;
        cost = num1 * 5.50;
        System.out.println("Normal Price: € " + df.format(cost));



        if (num1 < 25) {
            System.out.println("Your dicount is " + disc);
            totcost = cost - disc;
            System.out.print("Your total cost is € " + df.format(totcost));
        }

        else if (num1 >= 25) {
            disc = cost * 0.05;
            totcost = cost - disc;
            System.out.println("Your dicount is € " + df.format(disc));
            System.out.print("Your total cost is € " + df.format(totcost));
        }

        else if (num1 >= 50) {
            disc = cost * 0.1;
            totcost = cost - disc;
            System.out.println("Your dicount is € " + df.format(disc));
            System.out.print("Your total cost is € " + df.format(totcost));
        }

        else if (num1 >= 100) {
            disc = cost * 0.15;
            totcost = cost - disc;
            System.out.println("Your dicount is € " + df.format(disc));
            System.out.print("Your total cost is € " + df.format(totcost));
        }

        else if (num1 >= 150) {
            disc = cost * 0.2;
            totcost = cost - disc;
            System.out.println("Your dicount is € " + df.format(disc));
            System.out.print("Your total cost is € " + df.format(totcost));
        }

        else if (num1 >= 200) {
            disc = cost * 0.25;
            totcost = cost - disc;
            System.out.println("Your dicount is € " + df.format(disc));
            System.out.print("Your total cost is € " + df.format(totcost));

        }

        else if (num1 >= 300) {
            disc = cost * 0.3;
            totcost = cost - disc;
            System.out.println("Your dicount is € " + df.format(disc));
            System.out.print("Your total cost is € " + df.format(totcost));
        }

    }

}

Answer 1

万恶之源:

 else if (num1 >= 25) {

这会捕获从 25 到无穷大的所有数字。使用

 else if(num1 < 50) {

等等。在您分离完 300 以下的所有数量后，最后一个分支将不需要测试。

我想补充一点，代码重复并不好。避免这种情况的一种方法是使用

int[] limit = new int[]{ 25, 50, 100, 150, 200, 300 };
int[] disct = new int[]{  5, 10,  15,  20, 25,   30 }

int d = 0;
for( int i = 0; i < limit.length; ++i ){ 
    if( qtty < limit[i] ) break;
    d = disct[i];
}

double cost = qtty*price;
double discount = cost*d/100;
totcost = cost - discount;