Java-语法和逻辑错误，我找不到答案

Java程序运行不正常，我不知道问题出在哪里 还有构造函数，我要添加它 他们有很多问题，但我不知道如何解决，所以如果有人愿意帮忙，我会非常感激

//头文件

import java.util.*;
import java.io.*;

public class Phonedir
{
  public static void main(String [] args)
  {
    String First_name, Last_name, Phone_Num;
    String First, Last, Num;
    int choice=0;

    Scanner in = new Scanner(System.in);

    LinkedList<T> listOfTs = new LinkedList<T>();

    System.out.println("A Program to keep a Phone Directory:");

    //looping menu
    while(true)
    {
        Menu();

      //enter the choice
      if(choice==0)
        System.out.println("No choice selected");
      else  
        System.out.println(listOfTs.get(choice-1));

      System.out.print("Enter the choice ");
        String command = in.next().trim();

      //show all entries
      if(command.equalsIgnoreCase("a"))
      {
        System.out.println();
        System.out.println(First_name+" "+Last_name+" "+Phone_Num);


        //for loop
        for(int i=0; i<listOfTs.size(); i++)
          System.out.println(listOfRecords.get(i));

      }

      //Delete choice
      else if(command.equalsIgnoreCase("d"))
      {
        if(choice==0)
          System.out.println("No Record selected");
        else
        {
          System.out.println("Deleted: "+listOfRecords.remove(choice-1));
          choice=0;          //update choice counter of reference of linked list
        }

      }

      //change first name of choice Record
      else if(command.equalsIgnoreCase("f"))
      {
        if(choice==0)
          System.out.println("No Record selected");
        else
        {
          System.out.print("New first name: ");
            First = in.next().trim();

          listOfRecords.get(choice-1).changeFirst(First);
        }
      }

      //Change last name of selected record
      else if(command.equalsIgnoreCase("l"))
      {
        if(choice==0)
          System.out.println("No Record selected");
        else
        {
          System.out.print("New last name: ");
            Last = in.next().trim();

          listOfRecords.get(choice-1).changeLast(Last);
        }
      }

      //add new contact

      else if(command.equalsIgnoreCase("n"))
      {
        System.out.print("Enter first name: ");
                First_name = in.next().trim();
        System.out.print("Enter last name: ");
                Last_name = in.next().trim();
        //check in valid phone number input
        //if phone number does not equal 10 then reprompt
        while(true)
        {
          System.out.print("Enter phone number");
                  Phone_Num = in.next().trim();

          if(Phone_Num.length()!=10)
            System.out.println("Please enter correct phone number!");
          else
            break;
        }

        listOfRecords.add(new Record(First_name, Last_name, Phone_Num));
          choice = listOfRecords.size();
      }

      //Change phone number
      else if(command.equalsIgnoreCase("p"))
      {
        if(choice==0)
          System.out.println("No Record selected");
        else
        {
          System.out.print("Enter new phone number: ");
            Num = in.next().trim();

          listOfRecords.get(choice-1).changePhone(Num);
        }
      }

      //Exit
      else if(command.equalsIgnoreCase("q"))
      {
        System.out.println("Quit");
        System.exit(1);
      }


      else

      if(command.equalsIgnoreCase("s"))
      {

        String testName;
        int test=0;
        System.out.print("Enter first name: ");
          First_name = in.next().trim();

        for(int i=0; i<listOfRecords.size(); i++)
        {
          testName = listOfRecords.get(i).getFirst();
          if(testName.equals(First_name))
          {
            choice=i+1;
            test++;
          }
        }

        //print if no match found
        if(test==1);
          System.out.println("No Record found");
      }

      else
        System.out.println("Choice not correct");
    }
  }

  //print menu
  static void Menu()
  {
    System.out.println();
    System.out.println("\t(a) Show all records");
    System.out.println("\t(d) Delete the current record");
    System.out.println("\t(f) Change the first name in the current record");
    System.out.println("\t(l) Change the last name in the current record");
    System.out.println("\t(n) Add a new record");
    System.out.println("\t(p) Change the phone number in the current record");
    System.out.println("\t(q) Quit");
    System.out.println("\t(s) Select a record from the record list to become current record");
  }
}
      }

      //change first name of choice Record
      else if(command.equalsIgnoreCase("f"))
      {
        if(choice==0)
          System.out.println("No Record selected");
        else
        {
          System.out.print("New first name: ");
            First = in.next().trim();

          listOfRecords.get(choice-1).changeFirst(First);
        }
      }

      //Change last name of selected record
      else if(command.equalsIgnoreCase("l"))
      {
        if(choice==0)
          System.out.println("No Record selected");
        else
        {
          System.out.print("New last name: ");
            Last = in.next().trim();

          listOfRecords.get(choice-1).changeLast(Last);
        }
      }

      //add new contact

      else if(command.equalsIgnoreCase("n"))
      {
        System.out.print("Enter first name: ");
                First_name = in.next().trim();
        System.out.print("Enter last name: ");
                Last_name = in.next().trim();
        //check in valid phone number input
        //if phone number does not equal 10 then reprompt
        while(true)
        {
          System.out.print("Enter phone number");
                  Phone_Num = in.next().trim();

          if(Phone_Num.length()!=10)
            System.out.println("Please enter correct phone number!");
          else
            break;
        }

        listOfRecords.add(new Record(First_name, Last_name, Phone_Num));
          choice = listOfRecords.size();
      }

      //Change phone number
      else if(command.equalsIgnoreCase("p"))
      {
        if(choice==0)
          System.out.println("No Record selected");
        else
        {
          System.out.print("Enter new phone number: ");
            Num = in.next().trim();

          listOfRecords.get(choice-1).changePhone(Num);
        }
      }

      //Exit
      else if(command.equalsIgnoreCase("q"))
      {
        System.out.println("Quit");
        System.exit(1);
      }


      else

      if(command.equalsIgnoreCase("s"))
      {

        String testName;
        int test=0;
        System.out.print("Enter first name: ");
          First_name = in.next().trim();

        for(int i=0; i<listOfRecords.size(); i++)
        {
          testName = listOfRecords.get(i).getFirst();
          if(testName.equals(First_name))
          {
            choice=i+1;
            test++;
          }
        }

        //print if no match found
        if(test==1);
          System.out.println("No Record found");
      }

      else
        System.out.println("Choice not correct");
    }
  }

  //print menu
  static void Menu()
  {
    System.out.println();
    System.out.println("\t(a) Show all records");
    System.out.println("\t(d) Delete the current record");
    System.out.println("\t(f) Change the first name in the current record");
    System.out.println("\t(l) Change the last name in the current record");
    System.out.println("\t(n) Add a new record");
    System.out.println("\t(p) Change the phone number in the current record");
    System.out.println("\t(q) Quit");
    System.out.println("\t(s) Select a record from the record list to become current record");
  }
}

import java.util.*；
导入java.io.*；
公共类Phonedir
{
公共静态void main（字符串[]args）
{
字符串First_name、Last_name、Phone_Num；
字符串First，Last，Num；
int-choice=0；
扫描仪输入=新扫描仪（系统输入）；
LinkedList listOfTs=新建LinkedList（）；
System.out.println（“保存电话目录的程序：”）；
//循环菜单
while（true）
{
菜单（）；
//输入选项
如果（选项==0）
System.out.println（“未选择选项”）；
其他的
System.out.println（listOfTs.get（choice-1））；
系统输出打印（“输入选项”）；
String命令=in.next（）.trim（）；
//显示所有条目
if（command.equalsIgnoreCase（“a”））
{
System.out.println（）；
System.out.println（名字+姓氏+电话号码）；
//for循环
对于（int i=0；i我已经更正了您的代码。我能够成功地执行并插入少量记录

下面是两个类
Phonedir.java
和
Record.java

Phonedir.java

package stackoverflow;
import java.util.*;
import java.io.*;

public class Phonedir
{

    //print menu
      static void Menu()
      {
        System.out.println();
        System.out.println("\t(a) Show all records");
        System.out.println("\t(d) Delete the current record");
        System.out.println("\t(f) Change the first name in the current record");
        System.out.println("\t(l) Change the last name in the current record");
        System.out.println("\t(n) Add a new record");
        System.out.println("\t(p) Change the phone number in the current record");
        System.out.println("\t(q) Quit");
        System.out.println("\t(s) Select a record from the record list to become current record");
      }

  public static void main(String [] args)
  {
    String First_name, Last_name, Phone_Num;
    String First, Last, Num;
    int choice=0;

    Scanner in = new Scanner(System.in);

    LinkedList<Record> listOfRecords = new LinkedList<Record>();

    System.out.println("A Program to keep a Phone Directory:");

    //looping menu
    while(true)
    {
        Menu();

      //enter the choice
      if(choice==0)
        System.out.println("No choice selected");
      else  
        System.out.println(listOfRecords.get(choice-1));

      System.out.print("Enter the choice ");
        String command = in.next().trim();

      //show all entries
      if(command.equalsIgnoreCase("a"))
      {
        System.out.println();



        //for loop
        for(int i=0; i<listOfRecords.size(); i++) {
            Record record = listOfRecords.get(i);
             System.out.println(record.getFirstName() +" "+  record.getLastName() +" "+ record.getPhone());
        }


      }

      //Delete choice
      else if(command.equalsIgnoreCase("d"))
      {
        if(choice==0)
          System.out.println("No Record selected");
        else
        {
          System.out.println("Deleted: "+listOfRecords.remove(choice-1));
          choice=0;          //update choice counter of reference of linked list
        }

      }

      //change first name of choice Record
      else if(command.equalsIgnoreCase("f"))
      {
        if(choice==0)
          System.out.println("No Record selected");
        else
        {
          System.out.print("New first name: ");
            First = in.next().trim();

          listOfRecords.get(choice-1).setFirstName(First);
        }
      }

      //Change last name of selected record
      else if(command.equalsIgnoreCase("l"))
      {
        if(choice==0)
          System.out.println("No Record selected");
        else
        {
          System.out.print("New last name: ");
            Last = in.next().trim();

          listOfRecords.get(choice-1).setLastName(Last);
        }
      }

      //add new contact

      else if(command.equalsIgnoreCase("n"))
      {
        System.out.print("Enter first name: ");
                First_name = in.next().trim();
        System.out.print("Enter last name: ");
                Last_name = in.next().trim();
        //check in valid phone number input
        //if phone number does not equal 10 then reprompt
        while(true)
        {
          System.out.print("Enter phone number");
                  Phone_Num = in.next().trim();

          if(Phone_Num.length()!=10)
            System.out.println("Please enter correct phone number!");
          else
            break;
        }

        listOfRecords.add(new Record(First_name, Last_name, Phone_Num));
          choice = listOfRecords.size();
      }

      //Change phone number
      else if(command.equalsIgnoreCase("p"))
      {
        if(choice==0)
          System.out.println("No Record selected");
        else
        {
          System.out.print("Enter new phone number: ");
            Num = in.next().trim();

          listOfRecords.get(choice-1).setPhone(Num);
        }
      }

      //Exit
      else if(command.equalsIgnoreCase("q"))
      {
        System.out.println("Quit");
        System.exit(1);
      }


      else if(command.equalsIgnoreCase("s"))
      {

        String testName;
        int test=0;
        System.out.print("Enter first name: ");
          First_name = in.next().trim();

        for(int i=0; i<listOfRecords.size(); i++)
        {
          testName = listOfRecords.get(i).getFirstName();
          if(testName.equals(First_name))
          {
            choice=i+1;
            test++;
          }
        }


      }



      //change first name of choice Record
      else if(command.equalsIgnoreCase("f"))
      {
        if(choice==0)
          System.out.println("No Record selected");
        else
        {
          System.out.print("New first name: ");
            First = in.next().trim();

          listOfRecords.get(choice-1).setFirstName(First);
        }
      }

      //Change last name of selected record
      else if(command.equalsIgnoreCase("l"))
      {
        if(choice==0)
          System.out.println("No Record selected");
        else
        {
          System.out.print("New last name: ");
            Last = in.next().trim();

          listOfRecords.get(choice-1).setLastName(Last);
        }
      }

      //add new contact

      else if(command.equalsIgnoreCase("n"))
      {
        System.out.print("Enter first name: ");
                First_name = in.next().trim();
        System.out.print("Enter last name: ");
                Last_name = in.next().trim();
        //check in valid phone number input
        //if phone number does not equal 10 then reprompt
        while(true)
        {
          System.out.print("Enter phone number");
                  Phone_Num = in.next().trim();

          if(Phone_Num.length()!=10)
            System.out.println("Please enter correct phone number!");
          else
            break;
        }

        listOfRecords.add(new Record(First_name, Last_name, Phone_Num));
          choice = listOfRecords.size();
      }

      //Change phone number
      else if(command.equalsIgnoreCase("p"))
      {
        if(choice==0)
          System.out.println("No Record selected");
        else
        {
          System.out.print("Enter new phone number: ");
            Num = in.next().trim();

          listOfRecords.get(choice-1).setPhone(Num);
        }
      }

      //Exit
      else if(command.equalsIgnoreCase("q"))
      {
        System.out.println("Quit");
        System.exit(1);
      }


      else

      if(command.equalsIgnoreCase("s"))
      {

        String testName;
        int test=0;
        System.out.print("Enter first name: ");
          First_name = in.next().trim();

        for(int i=0; i<listOfRecords.size(); i++)
        {
          testName = listOfRecords.get(i).getFirstName();
          if(testName.equals(First_name))
          {
            choice=i+1;
            test++;
          }
        }

        //print if no match found
        if(test==1);
          System.out.println("No Record found");
      }

      else
        System.out.println("Choice not correct");
    }
  }


}

package stackoverflow;

public class Record {

    private String firstName;
    private String lastName;
    private String phone;

    public Record(String firstName, String lastName, String phone){
        this.firstName = firstName;
        this.lastName = lastName;
        this.phone = phone;
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public String getPhone() {
        return phone;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }



}

我还不能发表评论，所以我会回答这个问题

您的代码示例可读性不强。也许您可以尝试将其缩短
你有很多课外代码。检查你的家长
类型T未在
LinkedList listOfTs=new LinkedList（）；
我在代码中看到多个
static void Menu（）
方法。请为每个方法使用唯一的名称
将代码分成更小的部分
当你说“运转不正常”请具体说明。错误的具体原因是什么？或者与代码的预期行为相比，代码的行为是什么。没有人会在不知道他们在寻找什么的情况下查看您的代码。将您的程序缩减到一个更小的版本，使其正常工作，然后添加功能。您在第一个e中就吃了太多埃弗特。