Java：如何读取一个 int 的多个扫描仪值

Question

我一直试图弄清楚如何根据从Scanner 类获得的输入计算面积和体积。该练习包括一次接收多对半径和高度。

我已经编写了方法并对其进行了测试，所以它们应该可以工作。我遇到的问题是当我想使用来自“扫描仪”的输入并使用它们进行计算时。

这是我的代码（我没有包含方法）：

    Scanner keyboard = new Scanner(System.in); 

    int radius = 0;
    int height = 0;

    System.out.print("Enter values ");
    String input = keyboard.nextLine();

    String[] items = input.split(" ");
    int[] numbers = new int[items.length];

    for (int i = 0; i < items.length; i++)  
        {
            numbers[i] = Integer.parseInt(items[i]);
        } 

    for (int i = 0; i < numbers.length/2; i++)
    {
        numbers[i] = radius;
        numbers[i + 1] = height;

        double result = area(radius);
        double result1 = area (radius,height);
        double result2 = volume (radius,height);

        System.out.println("");
        System.out.print("r = " + radius + "    ");
        System.out.print("h = " + height);
        System.out.println("");
        System.out.print("Base area:    ");
        System.out.printf("%.2f", result);
        System.out.println("");
        System.out.print("Surface area: ");
        System.out.printf("%.2f", result1);
        System.out.println("");
        System.out.print("Volym:            ");
        System.out.printf("%.2f", result2);
        System.out.println("");
    }
    keyboard.nextLine(); 

结果如下：

Input: 2 4 5 1

Output: 


r = 0    h = 0

Base area:        0.00

Surface area:     0.00

Volym:            0.00



r = 0    h = 0

Base area:        0.00

Surface area:     0.00

Volym:            0.00

Answer 1

你必须这样做：

for (int i = 0; i < numbers.length; i+=2)
{
    radius = numbers[i];
    height = numbers[i + 1];
    .
    .
    .
}   

Answer 2

这两行是错误的：

numbers[i] = radius;
numbers[i + 1] = height;

radius 和 height 应该在左侧：

radius = numbers[i];
height = numbers[i + 1];

此外，如果您想将输入“分组”成对，这将不起作用：

radius = numbers[i];
height = numbers[i + 1];

这只会将输入分组，如“(0, 1), (1, 2)”。改用这个；

radius = numbers[i * 2];
height = numbers[i * 2 + 1];

Answer 3

import java.util.Scanner;
public class Test {
public static void main(String[] args) {
    Scanner keyboard = new Scanner(System.in);

    int radius = 0;
    int height = 0;

    System.out.print("Enter values ");
    String input = keyboard.nextLine();

    String[] items = input.split(" ");
    int[] numbers;

    if(items.length % 2 == 0){ //Making sure you are having even number of inputs
        numbers = new int[items.length];

        for (int i = 0; i < items.length; i++) {
            numbers[i] = Integer.parseInt(items[i]);
        }

        for(int i = 0,j = -1; i < numbers.length / 2; i++){
            radius = numbers[++j];
            height = numbers[++j];
            System.out.println("radius: " + radius + " height: " + height);

            //Write Your Area Volume Code Here and use the radius and height which is there in the loop for calculation
            //Your code goes here
            //Your code ends here
        }
    }else{
        System.out.println("Incorrect input provided");
    }
    keyboard.close();
}}

试试这件作品。示例输出如下：

输入值 1 2 3 4 5 6 7 8 9 10 半径：1 高度：2 半径：3 高度：4 半径：5 高度：6 半径：7 高度：8 半径：9 高度：10

谢谢

Answer 4

注意：半径和高度在第一次初始化后不会得到新值

Answer 5

试一下：

public class NewMain
{
class Crate
{
    public int radius;
    public int height;
}

public static void main(String[] args)
{
    Scanner keyboard = new Scanner(System.in);

    System.out.print("Enter values ");
    String input = keyboard.nextLine();

    String[] items = input.split(" ");
    Crate[] numbers = new Crate[items.length];

    for (int i = 0; i < items.length; i ++)
    {
        numbers[i].radius = Integer.parseInt(items[i * 2]);
        numbers[i].height = Integer.parseInt(items[i * 2 + 1]);
    }
}
}

Answer 6

我想你可以试试这个解决方案。

processItems() 方法清除了数字之间的所有white-spaces，这行代码if (integers.length % 2 == 0) 确保我们有偶数个输入。所以我们总是有一对数字（半径和高度）。

我还创建了一个类 InputPair 和一个 InputPair 数组来打印对保持模块化。

你可以用这个测试偶数个输入：

2 9 4 7 5 6 7 1 3 8 12 5 8 2 3 9 2 9 2 7

这对于奇数个输入：

2 9 4 5 6 7 1 3 8 12 5 8 6 3 9 2 9 2 7

您可以在这里找到full Java code

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Scanner;

public class Main {

    private static class InputPair {
        public int radius;
        public int height;

        public InputPair() {}

        public void printValues() {
            System.out.println("Radius: " + radius + " Height: " + height);
        }
    }

    public static void main(String[] args) {
        Scanner keyboard = new Scanner(System.in);

        System.out.print("Enter values ");
        String input = keyboard.nextLine();

        String[] items = input.split(" ");
        Integer[] integers = processItems(items);
        InputPair[] values = new InputPair[integers.length];

        System.out.println(Arrays.toString(items));
        System.out.println("items length:  " + items.length);

        System.out.println(Arrays.toString(integers));
        System.out.println("items length:  " + integers.length);

        if (integers.length % 2 == 0) { 
            for (int i = 0; i < integers.length / 2; i++) {
                System.out.print("Index:  " + i + " ");
                try {
                    values[i] = new InputPair();
                    values[i].radius = integers[i * 2];
                    values[i].height = integers[i * 2 + 1];
                    values[i].printValues();
                } catch (NullPointerException ne) {
                    System.out.println("Error NullPointerException");
                }

            }
        } else {
            System.out.println("The number of values bust be an even number. ");
        }
    }

    private static Integer[] processItems(String[] items) {
        List<Integer> numbers = new ArrayList<>();

        for (String s : items) {
            //Do your stuff here
            s = s.replaceAll("[^\\d]", "");
            if (!s.equals("")) {
                numbers.add(Integer.parseInt(s));
                System.out.println(Integer.parseInt(s));
            }
        }

        Integer[] stockArr = new Integer[numbers.size()];
        return numbers.toArray(stockArr);
    }
}