无法在循环中输入第一个字符串，它总是从java中的第二个输入开始

Question

我创建了一个 Employee 类，我只在其中传递值并打印数组。你可以看到：

package practicequestion;

import java.util.Scanner;
import practicequestion.employeeq.Employee;

public class EmployeeMain {
    public static void main(String[] args) {
        Employee[] obj = new Employee[3];
        Scanner sc = new Scanner(System.in);
        System.out.println("Enter the number of inputs you want ");
        int n = sc.nextInt();
        for (int i = 0; i < n; i++) {

            System.out.println("Enter FirstName");
            String firstname = sc.nextLine();
            System.out.println("Enter LastName");
            String lastname = sc.nextLine();
            System.out.println("Enter Email");
            String email = sc.nextLine();
            System.out.println("Enter Salary");
            int salary = sc.nextInt();
            System.out.println("Enter Mobile Number");
            long mobileno = sc.nextLong();
            System.out.println("Enter Experience");
            int empexp = sc.nextInt();
            System.out.println("Enter Employee Id");
            int empid = sc.nextInt();
            if (i < n) {
                obj[i] = new Employee(firstname, lastname, email, salary, empid, empexp, mobileno);
            }
        }
        for (int i = 0; i < 3; i++) {
            System.out.println("Employee " + i +  " values are: ");
            obj[i].Display();
        }
        if (sc != null) {
            sc.close();   
        }
    }

}

但我无法输入名字，因为每当我运行程序时，它都会从姓氏开始输入。它的类是这样的：

package practicequestion.employeeq;

public class Employee {
   String FirstName;
   String LastName;
   String Email;
   int Salary;
   long MobileNo;
   int EmployeeExp;
   int EmployeeId;

    public Employee(String FirstName,String LastName,String Email,int Salary,int EmployeeId,int EmployeeExp,long MobileNo) {
        this.FirstName = FirstName;
        this.LastName = LastName;
        this.Email = Email;
        this.Salary = Salary;
        this.EmployeeId = EmployeeId;
        this.EmployeeExp = EmployeeExp;
        this.MobileNo = MobileNo;
    }
    public void Display() {
        System.out.println(FirstName +"\n" + LastName + "\n" + Email + "\n" + Salary + "\n" + EmployeeId +"\n" + EmployeeId +"\n" + MobileNo);
    }
}

谁能解决这个问题？

Answer 1

试试这个。我将记录我所做的更改。

Scanner sc = new Scanner(System.in);
System.out.println("Enter the number of inputs you want ");
int n = sc.nextInt();
// allocate the Employee array after you get the number of inputs.
Employee[] obj = new Employee[n];

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

    // get the newline out of the buffer here. That also
    // takes care of the `nextInt` problem at the end of this loop
    sc.nextLine();
    
    System.out.println("Enter FirstName");
    String firstname = sc.nextLine();
    System.out.println("Enter LastName");
    String lastname = sc.nextLine();
    System.out.println("Enter Email");
    String email = sc.nextLine();
    System.out.println("Enter Salary");
    int salary = sc.nextInt();
    System.out.println("Enter Mobile Number");
    long mobileno = sc.nextLong();
    System.out.println("Enter Experience");
    int empexp = sc.nextInt();
    System.out.println("Enter Employee Id");
    int empid = sc.nextInt();
    // you don't need to verify `i` here.  The for loop does that
    // for you
    obj[i] = new Employee(firstname, lastname, email, salary,
            empid, empexp, mobileno);
    
}

// use the number of inputs `n` to limit the loop
for (int i = 0; i < n; i++) {
    System.out.println("Employee " + i + " values are: ");
    obj[i].Display();
}

关闭扫描仪通常不是一个好习惯。

Answer 2

这里已经回答了这个问题：Scanner is skipping nextLine() after using next() or nextFoo()?

基本上问题在于您在进入循环之前调用的 Scanner.nextInt() 。 Scanner.nextInt() 仅读取用户输入的下一个 Integer，而不是整行，因此当您在 Scanner.nextLine() 直接接受您输入整数的行的剩余（和空）部分之后调用它时。

要解决这个问题，您要么必须调用 Scanner.nextLine() 一次，要么使用 Scanner.nextLine() 获取 Integer，然后将其转换为 Integer。