正在获取错误消息“线程“ main”中的异常” java.util.InputMismatchException”

Question

public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int iteam = sc.nextInt();
    Student[] students = new Student[iteam];
    int id;
    String name;
    String city, s_city;
    double marks, s_marks;

    for (int i = 0; i < iteam; i++) {
        id = sc.nextInt();
        name = sc.nextLine();
        city = sc.nextLine();
        marks = sc.nextDouble();
        students[i] = new Student(id, name, city, marks);

    }
}

我收到一个错误“ 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.nextDouble(Unknown Source)"

我也尝试使用next（），但是存在相同的错误。并且我还导入java.util.Scanner。

Answer 1

当您从一行中读取一个数值，并期望用户点击回车来提交该值时，您必须先消耗行尾，然后才能继续。扫描仪不会自动执行此操作。要让用户输入4个值，每次输入后都按回车键，您的输入循环应如下所示：

for (int i = 0; i < iteam; i++) {

    id = sc.nextInt(); sc.nextLine();

    name = sc.nextLine();

    city = sc.nextLine();

    marks = sc.nextDouble(); sc.nextLine();

    students[i] = new Student(id, name, city, marks);

}

Answer 2

Scanner#nextLine

完整的示例：

public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int iteam = sc.nextInt();
    Student[] students = new Student[iteam];
    int id;
    String name;
    String city, s_city;
    double marks, s_marks;
    for (int i = 0; i < iteam; i++) {
        id = sc.nextInt();
        sc.nextLine();//call next line to prevent exception
        name = sc.nextLine();
        city = sc.nextLine();
        marks = sc.nextDouble();
        students[i] = new Student(id, name, city, marks);
    }
}

Answer 3

import java.util.Scanner;
public class MyClass {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int iteam = sc.nextInt();
        Student[] students = new Student[iteam];
        int id;
        String name;
        String city, s_city;
        double marks, s_marks;
        for (int i = 0; i < iteam; i++) {
            id = sc.nextInt();
            sc.nextLine();
            name = sc.nextLine();
            city = sc.nextLine();
            marks = sc.nextDouble();
            students[i] = new Student(id, name, city, marks);
        }
        for(Student s: students){
            System.out.println(s);
        }
    }
    private static class Student{
        private int id;
        private String name;
        private String city;
        private double marks;
        public Student(int id, String name, String city, double marks){
            this.id = id;
            this.name = name;
            this.city = city;
            this.marks = marks;
        }
        public String toString(){
            return "[Student] Id: "+this.id+", Name: "+this.name+", City: "+this.city+", Mark: "+this.marks;
        }
    }
}

为您提供一些解释：方法

public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int iteam;
    iteam = sc.nextInt();
    Student[] students = new Student[iteam];
    int id;
    String name;
    String city;
    double marks;

    for (int i = 0; i < iteam; i++) {
        id = sc.nextInt();
        name = sc.next();
        city = sc.next();
        marks = sc.nextDouble();
        students[i] = new Student(id, name, city, marks);
    }
}

，next()和nextInt()扫描下一个标记作为输入值。但最重要的是Return不算在内，因为您的bash将此视为您的输入。

此外，您的键盘输入是本地解释的，特别是如果您想读取双精度字。例如，英语分隔符写为
DOT，德语写为
COMMA。