java - 基础java，找不到错误

Question

尝试为我的编程入门类(class)编写这个程序。我无法让它运行，即使在添加打印机之前它也没有错误并且仍然无法运行。任何提示将不胜感激(如何修复它以及如何让打印机工作。

package pa2;

import java.io.PrintWriter;
import java.util.Scanner;

public class pa2 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub

    }

    {

        Scanner keyboard = new Scanner(System.in);

        PrintWriter prw = new PrintWriter ("pa2output.txt");

        // variables
        double tshirt, chips, coke, tax, sale, subtotal, total, tshirtcost, chipscost, cokecost, deposit, cokewdeposit, discount, change, payment, numshirt, numcoke, numchips;
        String name;
        tshirt = 18.95;
        chips = 1.79;
        coke = 2.99;
        deposit = 1.2;
        tax = .06;
        sale = .15;

        // menu
        System.out.print("What is your name? ");
        prw.print("What is your name? ");
        name = keyboard.nextLine();
        System.out.println("Welcome to Denny's " + name + "! " + "We have the following items for sale:");
        prw.print("Welcome to Denny's " + name + "! " + "We have the following items for sale:");
        System.out.println("T-shirt $" + tshirt + "15% off");
        prw.print("T-shirt $" + tshirt + "15% off");
        System.out.println("Chips $" + chips + "15% off");
        prw.print("Chips $" + chips + "15% off");
        System.out.println("Coke $" + coke);
        prw.print("Coke $" + coke);

        // input
        System.out.println("How many T-shirts do you want?");
        prw.print("How many T-shirts do you want?");
        numshirt = keyboard.nextDouble();
        System.out.println("How many bags of patato chips?");
        prw.print("How many bags of patato chips?");
        numchips = keyboard.nextDouble();
        System.out.println("What about 12-pack Coke?");
        prw.print("What about 12-pack Coke?");
        numcoke = keyboard.nextDouble();
        System.out.println("Please enter your payment: ");
        prw.print("Please enter your payment: ");
        payment = keyboard.nextDouble();
        // variables

        cokewdeposit = (deposit * numcoke);
        tshirtcost = (tshirt * numshirt);
        chipscost = (chips * numchips);
        cokecost = (coke * numcoke);
        subtotal = (tshirtcost + chipscost + cokecost + cokewdeposit);
        discount = (sale * subtotal);
        total = subtotal + (subtotal * tax) - discount;
        change = payment - total;

        // calculation
        System.out.println("Your total is $" + total);
        prw.print("Your total is $" + total);
        System.out.println(name + "here is your receipt");
        prw.print(name + "here is your receipt");
        System.out.println("item," + " " + "unit price," + " " + "how many," + " " + "cost");
        prw.print("item," + " " + "unit price," + " " + "how many," + " " + "cost");
        System.out.println("T-shirt ");
        prw.print("T-shirt ");
        System.out.print(tshirt + " " + numshirt + " " + (tshirt * numshirt));
        prw.print(tshirt + " " + numshirt + " " + (tshirt * numshirt));
        System.out.println("Chips ");
        prw.print("Chips ");
        System.out.print(chips + " " + numchips + " " + (chips * numchips));
        prw.print(chips + " " + numchips + " " + (chips * numchips));
        System.out.println("Coke" + coke);
        prw.print("Coke" + coke);
        System.out.print(coke + " " + numcoke + " " + (coke * numcoke));
        prw.print(coke + " " + numcoke + " " + (coke * numcoke));

        // receipt
        System.out.println("Discount " + subtotal);
        prw.print("Discount " + subtotal);
        System.out.println("Discount " + discount);
        prw.print("Discount " + discount);
        System.out.println("Tax " + tax);
        prw.print("Tax " + tax);
        System.out.println("Total " + total);
        prw.print("Total " + total);
        System.out.println("Payment " + payment);
        prw.print("Payment " + payment);
        System.out.println("Your change is " + change);
        prw.print("Your change is " + change);
        System.out.println("Thank you. Come again!");
        prw.print("Thank you. Come again!");


        keyboard.close();
        prw.close();
    }
}

Answer 1

您拥有的大代码块不是 main 的一部分，因此永远不会被调用。您必须 1) 放入 main，或 2) 放入从 main 调用的函数中。

现在，您只有代码卡在太空中，而您没有调用它。

对于初学者来说，也许可以将其扔掉:

private static void foo(){ 
   // stick block of code in here
}

然后从 main 中调用它，如下所示:

 public static void main(String [] args){
     foo();
 }