Java 菜单界面学生记录系统

我有一个部分工作的记录系统，但我的菜单界面有问题。基本上，菜单应允许您：

添加一个学生

删除学生

印刷学生

退出

现在菜单工作正常，但我在添加学生部分遇到问题。当他们添加学生时，他们需要：

• 输入名字的提示
• 姓氏提示
• 提示输入身份证号码

当他们这样做时，它会询问他们是否想再添加一个；如果输入“y”，它将再次循环，如果输入“n”，它将返回主菜单

现在在我的电脑上，当他们按“n”时，什么都不会发生，当你按y时，它会再次循环，但它不会让你为名字输入任何值

以下是系统的所有代码：

REGISTRYINTERFACE.java

/**
 * @version 1.0
 * @author parry2411 
 */
package student;

import java.util.Scanner;

    public class RegistryInterface
    {

        private Registry theRegistry = new Registry();
        Scanner input = new Scanner(System.in);

        public RegistryInterface(Registry theRegistry)
        {
        }

        public void doMenu()
        {
            boolean done = false;

            while (!done)
            {
                try
                {
                    System.out.println("\nRegistry Main Menu\n*******************\n");
                    System.out.println("1. Add a Student \n2. Delete a Student"
                            + "\n3. Print Registry\n0. Quit");

                    System.out.println("Select Option [1, 2, 3, 0] :>");
                    String userDecission = input.nextLine();

                    int decission = Integer.parseInt(userDecission);

                    switch (decission)
                    {
                        case 0:
                            System.out.println("System Closing Down..");
                            break;

                        case 1:
                            doAddStudent();
                            break;

                        case 2:
                            doDeleteStudent();
                            break;

                        case 3:
                            doPrintRegistry();
                            break;

                        default:
                            System.out.println("\nPlease Enter in a valid"
                                    + " Menu Option");
                            doMenu();
                            break;
                    }
                    done = true;
                }catch(Exception e)
                {
                    System.out.println("Incorrect Value Entered, Try Again....");
                }
            }
        }


    private void doAddStudent()
        {
            String addMore;
            do
            {
                System.out.println("\nAdd New Student\n***********\n");

                try
                {
                    System.out.println("Enter Students Forename :>");
                    String fName = input.nextLine();

                    System.out.println("Enter Student Surname :>");
                    String sName = input.nextLine();

                    System.out.println("Enter Student ID Number :>");
                    int idNum = input.nextInt();

                    theRegistry.addStudent(new Student(fName, sName, idNum));

                } catch (Exception e)
                {
                    System.out.println("\nERROR OCCURED: Incorect Value Entered"
                            + "\nTry Again... \nStudent Was NOT added");
                }


                System.out.println("\nAdd Another Student (Y/N) : >");
                addMore = input.next();



            } while (!"n".equals(addMore));
        }

        private void doDeleteStudent()
        {
            String another;
            do
            {
                System.out.println("\nDelete Student\n***********\n");
                System.out.println("Enter Student ID To Delete :>");
                try
                {
                    int studID = input.nextInt();
                    theRegistry.deleteStudent(studID);

                } catch (Exception e)
                {
                    System.out.println("\nERROR OCCURED: Incorect Value Entered"
                            + "\nTry Again...\n");
                }

                System.out.println("\nDelete Another? (Y/N)");
                another = input.next();


            } while (!"n".equals(another));
        }

        private void doPrintRegistry()
        {

            System.out.println("\nPrinting Registry\n***********\n");

            if(theRegistry.studentList.size() == 0)
            {
                System.out.println("The Student Record System Contains No Student"
                        + " Records, Please Add Students\n\n");
            }
            else
            {
               System.out.println(theRegistry.format()); 
                System.out.println("\n****Printing Finished........");
            }

            doMenu();

        }
    }

REGISTRY.java

/**
 * @version 1.0
 * @author parry2411 
 */
package student;

import java.util.Iterator;
import java.util.LinkedList;

public class Registry
{
    public LinkedList<Student> studentList = new LinkedList<>();
    public Iterator<Student> iter = studentList.iterator();

    public Registry()
    {
    }

    public void addStudent(Student aStudent)
    {
        Iterator<Student> addIterator = studentList.iterator();

        while (addIterator.hasNext())
        {
            Student ob = addIterator.next();
            if (ob.getStudentID() == aStudent.getStudentID())
            {
                System.out.println("This Student ID "
                        + ""+ aStudent.getStudentID()+ " Is Already Used"
                        + "\n Try Adding Again......");
                return;
            }
        }
        System.out.println("Student "+ aStudent.getForeName() + " "
                + "" + aStudent.getSurName() +" "
                + "Successfully Added To System.....");

        studentList.addLast(aStudent);
    }

    public void deleteStudent(int studentID)
    {
        Iterator<Student> deleteIterator = studentList.iterator();
        boolean removed = false;

        while(deleteIterator.hasNext())
        {
            Student ob = deleteIterator.next();

            if(ob.getStudentID() == studentID)
            {
                deleteIterator.remove();
                removed = true;
                System.out.println(ob.getForeName() + " " + ob.getSurName() + " Was Succesffully Removed from System. \n");
            }
        }
        if(!removed)
        {
            System.out.println("Student ID not found");
        }
    }

    public String format()
    {
        StringBuilder sB = new StringBuilder();
        Iterator<Student> formatIterator = studentList.iterator();

        while(formatIterator.hasNext())
        {
            Student ob = formatIterator.next();
            sB.append(ob.format());      
        }
        return sB.toString();
    }

    @Override
    public String toString()
    {
        Iterator<Student> toStringIterator = studentList.iterator();
        StringBuilder sB = new StringBuilder();

        while(toStringIterator.hasNext())
        {
            Student ob = toStringIterator.next();
            sB.append(ob.toString()).append("\n");
        }
        return sB.toString();
    }
}

Student.java

/**
 * @version 1.0
 * @author parry2411
 * Date Created: 18-Mar-2013
 */

package student;

public class Student 
{
    private String foreName;
    private String surName;
    private int studentID;


    public Student(String foreName, String surName, int studentID)
    {
        this.foreName = foreName;
        this.surName = surName;
        this.studentID = studentID;
    }

    public String getForeName()
    {
        return foreName;
    }

    public void setForeName(String foreName)
    {
        this.foreName = foreName;
    }

    public String getSurName()
    {
        return surName;
    }

    public void setSurName(String surName)
    {
        this.surName = surName;
    }

    public int getStudentID()
    {
        return studentID;
    }

    public void setStudentID(int studentID)
    {
        this.studentID = studentID;
    }

    @Override
    public String toString()
    {
        return getClass().getSimpleName()+"{" + "foreName=" + foreName + ", surName=" + surName + ", studentID=" + studentID + '}';
    }

    public String format()
    {
        return String.format("%-5s %-5s \t\t %-5d \n",foreName,surName,studentID);
    }
}

---

谢谢

将您的

DOADStudent

方法更改为以下方式：

private void doAddStudent()
    {
        String addMore;
        do
        {
            System.out.println("\nAdd New Student\n***********\n");

            try
            {
                System.out.println("Enter Students Forename :>");
                String fName = input.next();//use next() instead of nextLine()

                System.out.println("Enter Student Surname :>");
                String sName = input.next();//use next() instead of nextLine();

                System.out.println("Enter Student ID Number :>");
                int idNum = input.nextInt();

                theRegistry.addStudent(new Student(fName, sName, idNum));

            } catch (Exception e)
            {
                System.out.println("\nERROR OCCURED: Incorect Value Entered"
                        + "\nTry Again... \nStudent Was NOT added");
            }


            System.out.println("\nAdd Another Student (Y/N) : >");
            addMore = input.next();



        } while (!"n".equals(addMore));
    }

由于使用的是

Scanner.nextLine（）

，所以出现错误。现在的问题是为什么？

如官方文件所述：

使此扫描仪前进到当前行，并返回所需的输入 已跳过。此方法返回当前行的其余部分， 不包括末端的任何行分隔符。该位置设置为 下一行的开头

Scanner.next（）

无法正确终止分配的内存行。因此，当通过

String fName=input.nextLine（）调用
nextLine（）
时

after

addMore=input.next（）

在用户输入

y

之后，它实际上终止了前一行中实际包含值的内容——通过

next（）

输入，而不是接收新的

字符串

值。这就是它跳过用户输入内容的原因。因此，为了继续读取输入的值而不是前一个空行（因为

next（）

）返回的值没有终止），您可以使用根据官方文件规定的值：

查找并返回来自此扫描仪的下一个完整令牌。

更新
您还应替换：

String userDecission = input.nextLine();

到

---

您可以发布一个包含反映问题的代码的精简版本吗？基本上，错误发生在RegistryInterface类，老实说，我无法将其减少，因为问题可能在该类的任何地方。是的，它可能在任何地方-这就是问题的关键：如果您可以定位问题，你甚至不用发帖就能解决它。尝试阅读SSCCE页面。这已经起作用了，但当我按n键添加更多时，它应该会加载菜单，这只是添加If语句的情况吗？

String userDecission = input.nextLine();

String userDecission = input.next();