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尝试为我的编程课介绍做这个程序。我无法让它运行，甚至在我添加打印机之前它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印刷机工作。

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();
    }
}
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2 回答 2

4

您拥有的那一大块代码不是 main 的一部分，因此它永远不会被调用。您必须要么 1) 放入 main，或者 2) 放入从 main 调用的函数中。

现在你只是有代码在太空中闲逛，而你没有调用它。

也许先把它扔掉：

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

然后像这样从 main 调用它：

 public static void main(String [] args){
     foo();
 }
于 2013-09-26T22:33:55.867 回答
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只是对已接受答案的快速补充。

您编写的代码实际上位于完全有效的所谓“初始化块”中。然而，它通常用于“初始化”变量等。你可以用它们做什么是有限制的。（产生线程等的问题。）

IE：

    int a = 0;
    {
    //Your code
      a=3;
    }

里面的代码在编译时由编译器执行，但它并不意味着处理代码生成。只有变量初始化。下面使用“static”关键字的示例应该可以让您执行一些代码，但通常不是必需的。

int a=0;
static {
//Your code
a= 3;
// Other stuff
}

更好的计划是按照miss.serena所说的去做。这是一个解释初始化块如何工作的链接。

于 2014-02-12T17:53:43.347 回答