java - 尝试按键退出时类型不匹配

Question

这个问题已经有答案了:

Exception in thread "main" java.util.InputMismatchException (2 个回答)

已关闭 8 年前。

我有以下 Java 程序。

package Arrays;

import java.util.Scanner;

public class Arrays {
    public static void main(String[] args) {
        final int size = 5; // Size of the input Array

        Scanner input = new Scanner(System.in);
        while (!input.equals("q")) {
            System.out.println("Enter the 5 number you want to be stored in an array");

            // get the input of array from the user
            int a[] = new int[size];
            for (int i = 0; i < a.length; i++) {
                a[i] = input.nextInt();
            }

            /* Methods */
            System.out.println("\n");
            displayArray(a); // to display the numbers entered in Array
            System.out.println("\n");
            sumOfArray(a);// To print the sum of Array
            System.out.println("\n");
            productOfArray(a);// to print the product of Array
            System.out.println("\n");
            smallAndLargeOfArray(a);// to print the Max and Min number in Array
            System.out.println("\n");
            averageOfArray(a);// to print the average of Array
            System.out.println("\n");
        }
        input.close();
    }

    private static void displayArray(int arr[]) {
        System.out.print("The numbers you have inserted are ");
        for (int i = 0; i < arr.length; i++) {
            System.out.print(arr[i]);
            if (i < arr.length - 1) {
                System.out.print(", ");
            }
        }

    }

    private static void sumOfArray(int[] arr) {
        int sum = 0;
        for (int i = 0; i < arr.length; i++) {
            sum += arr[i];
        }
        System.out.print("Sum of array is " + sum);

    }

    private static void productOfArray(int[] arr) {
        int prod = 1;
        for (int i = 0; i < arr.length; i++) {
            prod *= arr[i];
        }
        System.out.print("Product of array is " + prod);
    }

    private static void smallAndLargeOfArray(int arr[]) {
        int minimim = Integer.MAX_VALUE;
        int maximum = Integer.MIN_VALUE;
        for (int i = 0; i < arr.length; i++) {
            if (minimim > arr[i]) {
                minimim = arr[i];
            }
            if (maximum < arr[i]) {
                maximum = arr[i];
            }
        }
        System.out.print("Minimum and Maximum numbers in array are " + minimim
                + " and " + maximum);

    }

    private static void averageOfArray(int arr[]) {
        int sum = 0;
        for (int i = 0; i < arr.length; i++) {
            sum += arr[i];
        }
        double avg = sum / 5;
        System.out.print("Average of array is " + avg);

    }

}

这里我试图继续该程序直到用户输入 q ，但是当我输入 q 时它抛出以下错误。

Exception in thread "main" java.util.InputMismatchException
at java.util.Scanner.throwFor(Unknown Source)
at java.util.Scanner.next(Unknown Source)
at java.util.Scanner.nextInt(Unknown Source)
at java.util.Scanner.nextInt(Unknown Source)
at Arrays.Arrays.main(Arrays.java:16)

请让我知道我哪里出了问题以及如何解决这个问题。

谢谢

Answer 1

您应该这样做，因为您正在比较您的 Scanner 对象

String inputName=""
Scanner input = new Scanner(System.in);
inputName= in.nextLine();
        while (!inputName.equals("q")) {..}

由于扫描仪对象不等于“q”(它是一个字符串)，因此 while 循环连续运行。然后扫描仪等待一个整数，但它需要一个字符。所以扫描器抛出异常(说输入无法转换成整数值)

阅读:

• How can I read input from the console using the Scanner class in Java?

• Exception in thread main java.util.InputMismatchException error