java.util.NoSuchElementException 错误？

Question

我是初学者 Java 程序员，我试图编写一个程序，允许用户通过输入名称、数量和质量来制作 Fruit 对象。我用构造函数做了一个单独的水果 class。当我要求用户输入名称时，一切正常，但是当它到达 quantity/mass 时，我收到 java.util.NoSuchElementException 运行时错误。

这是我的代码

public class Fruit {

    String Name;
    int Quantity;
    double Mass;

    public Fruit (String Name, int Quantity, double Mass){
        this.Name = Name;
        this.Quantity = Quantity;
        this.Mass = Mass;
    }

    public void Information(){
        System.out.println("This fruit is an " + Name + " and there's " + Quantity + " of it");
    }
}

import java.util.Scanner;

public class Fruits {

    public static void main (String[] args){

        Fruit Apple = new Fruit("Apple", 5, 32.6);
        System.out.println (Apple.Name);

            System.out.println("What would you like to name the fruit?: ");
            Scanner name1 = new Scanner (System.in);
            String name = name1.nextLine();
            name1.close();

            System.out.println("How much fruits are there?: ");
            Scanner quant1 = new Scanner (System.in);
            int quantity = quant1.nextInt();
            quant1.close();

            System.out.println("What is the mass of the Fruit?: ");
            Scanner mass1 = new Scanner (System.in);
            double mass = mass1.nextDouble();
            mass1.close();

            Fruit newFruit = new Fruit (name, quantity, mass);

            newFruit.Information();

    }
}

Answer 1

您不需要创建多个扫描仪对象。当您关闭第一个扫描仪时，实际上您正在关闭 System.in。所以第二个元素取不到System.in。所以最好使用单一扫描仪进行所有输入检索

        Scanner scanner = new Scanner (System.in);
        System.out.println("What would you like to name the fruit?: ");
        String name = scanner.nextLine();
        System.out.println("How much fruits are there?: ");
        int quantity = scanner.nextInt();
        System.out.println("What is the mass of the Fruit?: ");
        double mass = scanner.nextDouble();

java.util.NoSuchElementException 错误？

java.util.NoSuchElementException Error?

java

eclipse

java.util.scanner