如何将扫描仪放入方法中并将其输出放在不同的方法上

Question

我想通过扫描器类询问用户，但我希望该扫描器位于名为 readInput() 的方法中，并使用 gett-setter 在名为 writeOutput() 的不同方法上进行输出，

这是我的代码如下：

public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        LaboratoryExercise2 gro = new LaboratoryExercise2();
        String[] SecondQuestion;
        System.out.println("Select the item your purchasing.");
            String Product1  = sc.nextLine();
        System.out.println("Enter the Quantity and price separated by SPACE.");
            SecondQuestion = sc.nextLine().split(" ");
                int Quantity1 = Integer.parseInt(SecondQuestion[0]);
                double Price1 = Double.parseDouble(SecondQuestion[1]);
                double Amount1 = 0;
                Amount1 = Quantity1 * Price1;
                int Quantity = 0 + Quantity1;
                double Amount = 0 + Amount1;
                double Price = 0 + Price1;

我想要的输出这

        gro.setGrocery(Price, Quantity, Amount);
    System.out.println("You've selected " + gro.getitemQuantity() + " " + Product1 + " " + "at " + " " + 
                                                                            gro.getitemPrice() + " each");

    System.out.println("Amount due is " + gro.getamountDue());

是我的整个代码：

import java.util.Scanner; 

public class LaboratoryExercise2 {

private double itemPrice;
private int itemQuantity;
private double amountDue;


public void setGrocery(double newitemPrice, int newitemQuantity, double newamountDue) {

    itemPrice = newitemPrice;
    itemQuantity = newitemQuantity;
    amountDue = newamountDue;
}

public double getitemPrice() {
    return itemPrice;
    
}

public int getitemQuantity() {
    return itemQuantity;
    
}

public double getamountDue() {
    return amountDue;
    
}



public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    
    
    LaboratoryExercise2 gro = new LaboratoryExercise2();
    String[] SecondQuestion;

    System.out.println("Select the item your purchasing.");
        String Product1  = sc.nextLine();
        
        
        
    System.out.println("Enter the Quantity and price separated by SPACE.");
        SecondQuestion = sc.nextLine().split(" ");
        
            int Quantity1 = Integer.parseInt(SecondQuestion[0]);
            double Price1 = Double.parseDouble(SecondQuestion[1]);
            double Amount1 = 0;
            Amount1 = Quantity1 * Price1;
            int Quantity = 0 + Quantity1;
            double Amount = 0 + Amount1;
            double Price = 0 + Price1;

    gro.setGrocery(Price, Quantity, Amount);
    System.out.println("You've selected " + gro.getitemQuantity() + " " + Product1 + " " + "at " + " " + 
                                                                            gro.getitemPrice() + " each");

    System.out.println("Amount due is " + gro.getamountDue());
    
}   

}

Answer 1

将所有代码堆放在 main 中是一个坏主意。 Java 是面向对象的，而 main 作为静态，则不是。

在方法之间共享数据的解决方案通常是创建一个字段。

class Main {
  public static void main(String[] args) throws Exception {
    new Main().go();
  }

  private Scanner scanner;

  void go() throws Exception {
    scanner = new Scanner(System.in);
    scanner.useDelimiter("\\R");

    int quantity = askInt("Enter the quantity: ");
  }

  private int askInt(String prompt) {
    while (true) {
      System.out.print(prompt);
      if (scanner.hasNextInt()) return scanner.nextInt();
      scanner.next(); // eat the non-int token
      System.out.println("ERROR: Please enter an integer number.");
    }
  }
}

几乎所有命令行 java 应用程序都应该是这样的：一个单行 main 方法，除了 main 之外的任何地方都不使用 static，一个 < code>scanner 字段，使用正确的分隔符设置（\\R，这意味着 .nextX() 始终读取一行输入；使用 .next() 读取整行。永远不要调用 .nextLine() 以及所有其他 next 方法以令人讨厌的方式进行交互，这会使扫描器变得毫无用处，或者至少难以操作且容易出错。 “提示”行，这就是你这样做的原因。