我的 Java 程序拒绝接受字符串输入

Question

我有一个字符串数组 - name[]。当我尝试使用 Scanner 类从用户那里获取输入时，程序似乎忽略了该语句并继续下一个。import java.util.Scanner;class Student { //start of class    public static void main(String[] args) { //start of method main        Scanner sc = new Scanner(System.in);        System.out.print("Enter number of students: ");        int n = sc.nextInt();        String name[] = new String[n];        int totalmarks[] = new int[n];        for (int i = 0; i < n; i++) {            System.out.println("Student " + (i + 1));            System.out.print("Enter name: ");            name[i] = sc.nextLine();            System.out.print("Enter marks: ");            totalmarks[i] = sc.nextInt();        }        int sum = 0;        for (int i = 0; i < n; i++) {            sum = sum + totalmarks[i]; //calculating total marks        }        double average = (double) sum / n;        System.out.println("Average is " + average);        for (int i = 0; i < n; i++) {            double deviation = totalmarks[i] - average;            System.out.println("Deviation of " + name[i] + " is " + deviation);        }    } //end of method main} //end of class

Answer 1

那是因为该sc.nextInt()方法不会读取您输入中的换行符，因此您需要调用sc.nextLine()

从文档

将此扫描器前进到当前行并返回被跳过的输入。

此方法返回当前行的其余部分，不包括末尾的任何行分隔符。位置设置为下一行的开头。

由于此方法继续搜索输入以查找行分隔符，因此如果不存在行分隔符，它可能会缓冲所有搜索要跳过的行的输入。

您的代码现在看起来像：

public static void main(String[] args) {

    Scanner sc = new Scanner(System.in);

    System.out.print("Enter number of students: ");

    int n = sc.nextInt();

    sc.nextLine();                         // <----- observe this

    String name[] = new String[n];

    int totalmarks[] = new int[n];

    for (int i = 0; i < n; i++) {

        System.out.println("Student " + (i + 1));

        System.out.print("Enter name: ");

        name[i] = sc.nextLine();

        System.out.print("Enter marks: ");

        totalmarks[i] = sc.nextInt();

        sc.nextLine();                     // <----- observe this  

    }

    int sum = 0;

    for (int i = 0; i < n; i++) {

        sum = sum + totalmarks[i];

    }

    double average = (double) sum / n;

    System.out.println("Average is " + average);

    for (int i = 0; i < n; i++) {

        double deviation = totalmarks[i] - average;

        System.out.println("Deviation of " + name[i] + " is " + deviation);

    }

}

Answer 2

试试这个..你的 sc.nextLine() 在你输入整数值后读取空字符串

import java.util.Scanner;

class Student

    {//start of class

        public static void main(String[] args)

        {//start of method main

        Scanner sc = new Scanner(System.in);

        System.out.print("Enter number of students: ");

        int n = sc.nextInt();

        String emp = sc.nextLine();

        String name[] = new String[n];

        int totalmarks[] = new int[n];

        for (int i=0;i<n;i++)

        {

        System.out.println("Student " + (i + 1));

        System.out.print("Enter name: ");

        name[i] = sc.nextLine();

        System.out.print("Enter marks: ");

        totalmarks[i] = sc.nextInt();

        emp = sc.nextLine();

        }

        int sum = 0;

        for (int i = 0; i < n; i++)

        {

        sum = sum + totalmarks[i];//calculating total marks

        }

        double average = (double) sum / n;

        System.out.println("Average is " + average);

        for (int i = 0; i < n; i++)

        {

        double deviation = totalmarks[i] - average;

        System.out.println("Deviation of " + name[i] + " is " + deviation);

        }

        }//end of method main

        }//end of class