Question

我是编码的新手，并且在令牌“。”上一直遇到语法错误。在第21、22和23行（System.out.println）。我能弄清楚我们是错误的吗？

// calculator for the price of milk
import java.util.Scanner;
public class DairyCalculator
{

 public static void main( String [] args)
 {
    double cartonhold = 3.78;
    double productioncost = 0.38;
    double cartonprofit = 0.27;

    Scanner sc = new Scanner(System.in);

    System.out.print( "Enter how many liters of milk was produced; "); // input
    double produced = sc.nextInt();

    double cartonsneeded = produced / cartonhold;


     int System.out.println( "Milk cartons needed" = cartonsneeded);
     double System.out.println("Cost of production" = produced * productioncost);
     double System.out.println("Profit" = produced * cartonprofit);

    sc.close();
   }
}

Answer 1

将代码更新为

// calculator for the price of milk
import java.util.Scanner;

public class DairyCalculator {

public static void main(String[] args) {
    double cartonhold = 3.78;
    double productioncost = 0.38;
    double cartonprofit = 0.27;

    Scanner sc = new Scanner(System.in);

    System.out.print("Enter how many liters of milk was produced; "); // input
    double produced = sc.nextInt();

    double cartonsneeded = produced / cartonhold;

    System.out.println("Milk cartons needed = " + cartonsneeded);
    System.out.println("Cost of production = " + produced * productioncost);
    System.out.println("Profit = " + produced * cartonprofit);

    sc.close();
}
}

在System.out ..之前不需要int和double，并且还可以阅读有关Java语法的更多信息。您可以使用'+'运算符来连接字符串

Answer 2

每个System.out.println()语句中都有一个错误。该语句用于在控制台上打印输出。因此，您不能将其声明为int，double或任何其他数据类型。因此，每个打印语句中都有一个简单的语法错误。 =也是一个赋值运算符。如果要将其打印为控制台输出，则必须将其括在反逗号中。并使用+运算符来连接两个字符串。因此正确的代码如下：

// calculator for the price of milk
import java.util.Scanner;

public class DairyCalculator {
    public static void main( String [] args) {
        double cartonhold = 3.78;
        double productioncost = 0.38;
        double cartonprofit = 0.27;

        Scanner sc = new Scanner(System.in);

        System.out.print( "Enter how many liters of milk was produced; "); // input
        double produced = sc.nextInt();

        double cartonsneeded = produced / cartonhold;

        System.out.println("Milk cartons needed = " + cartonsneeded);
        System.out.println("Cost of production = " + produced * productioncost);
        System.out.println("Profit = " + produced * cartonprofit);

        sc.close();
    }
}

Answer 3

请勿在{{1}}之前使用数据类型，因为它仅用于打印目的，而数据类型用于变量声明。

在“”引号中，您可以写下要打印的任何消息，即，即您要提供的硬编码消息。

System.out.println运算符“”之后用于将所需对象的值连接到硬编码消息中。

为此，您使用+运算符并在其后写对象名称，该名称将打印硬编码消息和要打印的对象的值。

Java新手并不断获取语法错误

3 个答案: