Question

有一个恭维错误，说明类名已定义，我找不到解决方法

此类名称仅被声明一次，无法找到出错的地方

package practo;
import java.io.*;
import java.lang.*;
import java.util.*;

@SuppressWarnings("unused")
class Customer     /* compilation error occurs here */
{
    private int id;
    private String name;
    private String email;
    private String address;
    void setid(int id)
    {
        this.id=id;
    }
    int getid()
    {
        return id;
    }
    void setname(String name)
    {
        this.name=name;
    }
    String getname()
    {
        return name;
    }
    void setemail(String email)
    {
        this.email=email;
    }
    String getemail()
    {
        return email;
    }
    void setaddress(String address)
    {
        this.address=address;
    }
    String getaddress()
    {
        return address;
    }
    class PhoneNumber
    {
        private String phoneNumber;
        private String heldFromDate;
        private String heldToDate;
        void setphoneNumber(String phoneNumber)
        {
            this.phoneNumber=phoneNumber;
        }
        String getphoneNumber()
        {
            return phoneNumber;
        }

        void setheldToDate(String heldToDate)
        {
            this.heldToDate=heldToDate;
        }
        String getheldToDate()
        {
            return heldToDate;
        }

        public String getHeldFromDate() {
            return heldFromDate;
        }
        public void setHeldFromDate(String heldFromDate) {
            this.heldFromDate = heldFromDate;
        }
        class NumberType
        {
            private String code;
            private String description;
            void setcode(String code)
            {
                this.code=code;
            }
            void setdescription(String description)
            {
                this.description=description;
            }
            String getcode()
            {
                return code;
            }
            String getdescription()
            {
                return description;
            }
        }
    }
}

class x1
{
    public void main(String args[])
    {
        @SuppressWarnings("resource")
        Scanner s=new Scanner(System.in);
        Customer c=new Customer();
        Customer.PhoneNumber p=c.new PhoneNumber();
        Customer.PhoneNumber.NumberType n=p.new NumberType();
        System.out.println("Enter the customer details");
        System.out.println("Enter the  id :");
        int id=s.nextInt();
        c.setid(id);
        System.out.println(c.getid());
        System.out.println("Enter the name :");
        String name=s.nextLine();
        c.setname(name);
        System.out.println(c.getname());
        System.out.println("Enter the email :");
        String email=s.nextLine();
        c.setemail(email);
        System.out.println(c.getemail());
        System.out.println("Enter the address :");
        String address=s.nextLine();
        c.setaddress(address);
        System.out.println(c.getaddress());
        System.out.println("Enter the customer contact details");
        System.out.println("Enter the phone number :");
        String phoneNumber=s.nextLine();
        p.setphoneNumber(phoneNumber);
        System.out.println(p.getphoneNumber());
        System.out.println("Enter the held from date (dd/MM/yyyy)  :");
        String heldFromDate=s.next();
        p.setHeldFromDate(heldFromDate);
        System.out.println(p.getHeldFromDate());
        System.out.println("Enter the held to date (dd/MM/yyyy)  :");
        String heldToDate=s.next();
        p.setheldToDate(heldToDate);
        System.out.println(p.getheldToDate());
        System.out.println("Enter number type code :");
        String code=s.next();
        n.setcode(code);
        System.out.println(n.getcode());
        System.out.println("Enter number type description");
        String description=s.next();
        n.setdescription(description);
        System.out.println(n.getdescription());
    }

}

Answer 1

您能否确认客户类别不重复？如果不存在，可以从“项目”菜单中选择“清除”，它可能会修复这些错误。有时候日食困扰着我们。

Answer 2

检查包Customer中是否有另一个名为practo的班级。这会导致名称冲突。

Answer 3

您的课程没有给我任何编译错误。您可以尝试将该类设为公共，即public class Customer和名称为Customer.java的文件名。包practo已经包含名为Customer的类。

可能会发生

Answer 4

许多改进建议：

每个文件打开公共类，每个类打开一个文件。你的安排令人困惑。
学习并遵循Java编码标准。
使用Date作为日期而不是String是一种更好的设计，特别是对于JDK 8和java.time包。
学习JUnit而不是x1.main。

这些是您的课程外观的示例。

Customer.java

    package practo;

/**
 * Created by Michael
 * Creation date 5/29/2016.
 * @link https://stackoverflow.com/questions/37511168/it-show-the-error-that-customer-is-already-defined-please-let-me-know-whats-wron
 */
public class Customer {

    private int id;
    private String name;
    private String email;
    private String address;

    public Customer() {
        this(0, "", "", "");
    }

    public Customer(int id, String name, String email, String address) {
        this.id = id;
        this.name = name;
        this.email = email;
        this.address = address;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }
}

PhoneNumber.java：

package practo;

/**
 * Created by Michael
 * Creation date 5/29/2016.
 * @link https://stackoverflow.com/questions/37511168/it-show-the-error-that-customer-is-already-defined-please-let-me-know-whats-wron
 */
public class PhoneNumber {

    private String phoneNumber;
    private String heldFromDate;  // Bad design.  This ought to be a Date, not a String
    private String heldToDate;    // Bad design.  This ought to be a Date, not a String

    public PhoneNumber() {
        this("", "", "");
    }

    public PhoneNumber(String phoneNumber, String heldFromDate, String heldToDate) {
        this.phoneNumber = phoneNumber;
        this.heldFromDate = heldFromDate;
        this.heldToDate = heldToDate;
    }

    public String getPhoneNumber() {
        return phoneNumber;
    }

    public void setPhoneNumber(String phoneNumber) {
        this.phoneNumber = phoneNumber;
    }

    public String getHeldFromDate() {
        return heldFromDate;
    }

    public void setHeldFromDate(String heldFromDate) {
        this.heldFromDate = heldFromDate;
    }

    public String getHeldToDate() {
        return heldToDate;
    }

    public void setHeldToDate(String heldToDate) {
        this.heldToDate = heldToDate;
    }
}

它显示了客户已经定义的错误。请让我知道什么是错的以及如何纠正它

4 个答案: