java - 字符串值数据成员被编译器跳过

Question

这个问题已经有答案了:

Scanner is skipping nextLine() after using next() or nextFoo()? (25 个回答)

已关闭 3 年前。

尽管告诉计算机显示，但字符串值并未全部显示，请帮忙

import java.util.Scanner;

class Author
{
    private String name;
    private String email;
    private char gender;

    public Author (String name, String email, char gender) {
        this.name=name;
        this.setEmail(email);
        this.gender=gender;
    }

    /**
     * @return the name
     */
    public String getName() {
        return name;
    }

    /**
     * @return the email
     */
    public String getEmail() {
        return email;
    }
    /**
     * @param email the email to set
     */
    public void setEmail(String email) {
        this.email = email;
    }
    /**
     * @return the gender
     */
    public char getGender() {
        return gender;
    }

    @Override
    public String toString() {
        return "Author [name=" + name + ", email=" + email + ", gender=" + gender + "]";
    }


}
class Book
{
    private String Name;
    Author auth;
    private double price;
    private int qty;

    /**
     * @param name
     * @param auth
     * @param price
     */
    public Book(String name, Author auth, double price) {
        super();
        Name = name;
        this.auth = auth;
        this.price = price;
    }

    /**
     * @param name
     * @param auth
     * @param price
     * @param qty
     */
    public Book(String name, Author auth, double price, int qty) {
        super();
        Name = name;
        this.auth = auth;
        this.price = price;
        this.qty = qty;
    }

    public String getName() {
        return Name;
    }


    public Author getAuth() {
        return auth;
    }



    public double getPrice() {
        return price;
    }

    public void setPrice(double price) {
        this.price = price;
    }

    public int getQty() {
        return qty;
    }

    public void setQty(int qty) {
        this.qty = qty;
    }

    @Override
    public String toString() {
        return "Book [Name=" + Name + ", auth=" + auth + ", price=" + price + ", qty=" + qty + "]";
    }



}
class Student
{
    private String Name;
    private int roll;
    date issueDate;
    date returnDate;
    /**
     * @param name
     * @param roll
     * @param issueDate``
     * @param returnDate
     */
    public Student(String name, int roll, date issueDate, date returnDate) {
        super();
        Name = name;
        this.roll = roll;
        this.issueDate = issueDate;
        this.returnDate = returnDate;
    }
    public String getName() {
        return Name;
    }

    public int getRoll() {
        return roll;
    }

    public date getIssueDate() {

        return issueDate;
    }

    public date getReturnDate() {
        return returnDate;
    }
    public void setReturnDate(date returnDate) {
        this.returnDate = returnDate;

    }



}
public class Main {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner sc=new Scanner(System.in);
        Author ahTeck=null;
        System.out.println("How many Book are there in library ?");
        int n=sc.nextInt();
        Book []ob=new Book[n];
        for(int i=0;i<n;++i)
        {   System.out.println("Author's name");
            String s=sc.nextLine();
            sc.nextLine();
            System.out.println("Author's Email Id");
            String s1=sc.nextLine();
            System.out.println("gender:");
            char c = sc.next(".").charAt(0);
            sc.nextLine();
            System.out.println("Book Name:");
            String b=sc.nextLine();
            System.out.println("Book price:");
            double price=sc.nextInt();
            System.out.println("Book quantity");
            int q=sc.nextInt();
            ob[i]=new Book(b, new Author(s, s1, c),price,q);
            System.out.println(ob[i]);
        }

    }

}

问题出现在 https://www.ntu.edu.sg/home/ehchua/programming/java/J3f_OOPExercises.html

输出如下

Book [Name=g, auth=Author [name=, email=e, gender=m], price=6.0, qty=6]

跳过作者姓名的显示

Answer 1

啊是的。老扫描仪。

在顶部输入整数后，立即调用 sc.nextLine();

int n = sc.nextInt();
sc.nextLine();

实际上，您甚至不必在输入字符串或字符后调用 sc.nextLine()。问题是，当您输入数字时，您也会按回车键。当您使用 nextInt() 时，Scanner 类将其视为另一个 token ，因此数字会正确存储，但回车键 \n 会被视为另一个 token .

因此，当您在输入数字后调用 nextLine() 时，系统会发现 Scanner 对象中已经剩余了一个 token ，因此它将 '\n' 作为其输入。因此，该名称实际上存储了“\n”，它是空的。