arraylist java。util。尝试使用迭代器时发生ConcurrentModificationException错误
我正在编写一个程序,其中我创建了一个ArrayList
,我想用迭代器遍历列表:
ArrayList<Person> flightAttendants = new ArrayList<Person>();
Iterator<Person> itr = flightAttendants.iterator();
我正在尝试遍历arraylist的元素:
我还定义了一个toString
方法:
while(itr.hasNext())
{
System.out.println(itr.next());
}
public String toString()
{
System.out.println("name of the passenger : "+name);
System.out.println("Age of the passenger : "+age);
System.out.println("Seat number of the passenger : "+seatNumber);
return "\n";
}
每当我尝试运行它时,它都会给我一个错误:java。util。ConcurrentModificationException
这里的错误在哪里
更新:以下是完整代码:
import java.util.*;
import java.io.*;
class Person
{
Integer age;
String name;
String seatNumber;
Integer fare;
int pnr;
Person()
{
try
{
BufferedReader b = new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter the name of the passenger");
name = b.readLine();
System.out.println("Enter the age of the passenger");
age = Integer.parseInt(b.readLine());
System.out.println("Enter the Seat Number you want");
seatNumber = b.readLine();
pnr = (int)(Math.random()*100000000);
System.out.println("PNR number of the passenger is : "+pnr);
}
catch(Exception e)
{
System.out.println("");
}
}
public String toString()
{
System.out.println("name of the passenger : "+name);
System.out.println("Age of the passenger : "+age);
System.out.println("Seat number of the passenger : "+seatNumber);
return "\n";
}
}
class EconomyPassenger extends Person
{
}
class BusinessPassenger extends Person
{
}
class Crew extends Person
{
}
public class Airline
{
public static void main(String[] args)
{
ArrayList<Person> flightAttendants = new ArrayList<Person>();
Iterator<Person> itr = flightAttendants.iterator();
while(true)
{
try
{
System.out.println("Welcome to Indigo!!!");
BufferedReader b = new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter your Choice");
System.out.println("1.Book Tickets");
System.out.println("2.Check Reservation");
System.out.println("3.Update Tickets");
System.out.println("4.Exit");
int choice=Integer.parseInt(b.readLine());
if(choice<0 || choice>4)
{
throw new InvalidChoiceException("Enter a valid choice between 1 and 4");
}
switch(choice)
{
case 1: System.out.println("\n\n1.Economy*******2.Business*******3.Crew Login*******4.Exit");
// BufferedReader c = new BufferedReader(new InputStreamReader(System.in));
int c = Integer.parseInt(b.readLine());
if(c==1)
{
flightAttendants.add(new EconomyPassenger());
}
else if(c==2)
{
flightAttendants.add(new BusinessPassenger());
}
else if(c==3)
{
flightAttendants.add(new Crew());
}
else if(c==4)
{
break;
}
break;
case 2: // System.out.println("Enter your PNR Number : ");
// int p = Integer.parseInt(b.readLine());
// System.out.println(p);
while(itr.hasNext())
{
System.out.println(itr.next());
}
break;
case 3: System.out.println("case 3");break;
case 4: return;
default: System.out.println("default");
}
}
catch(InvalidChoiceException ic)
{
// System.out.println(ic);
}
catch(Exception e)
{
System.out.println(e);
}
}
}
}
class InvalidChoiceException extends Exception
{
InvalidChoiceException()
{}
InvalidChoiceException(String msg)
{
System.out.println(msg);
}
}
# 1 楼答案
你提供的代码应该可以很好地工作,因为我已经尝试过了。除非你表明你的代码正在处理其他问题,否则我们无法进一步尝试解决。我建议您也检查一下问题Iterators and the concurrentmodificationexception,以便更好地理解您的代码可能在某个地方出现了上面提到的错误
正如Andrew提到的,将迭代器引入while循环,现在就可以正常工作了。我试过了