how to create Synchronized arraylist

Question

i have created synchronized arrayList like this

import java.text.SimpleDateFormat;
import java.util.*;


class HelloThread  
{

 int i=1;
 List arrayList;
           


        

Answer 1

As Spike said, you can't modify a collection while iterating it. However, I think the solution is to lock the list while iterating.

class HelloThread  
{

 int i=1;
 List arrayList;
  public  void go()
  {
 arrayList=Collections.synchronizedList(new ArrayList());
 Thread thread1=new Thread(new Runnable() {

  public void run() {
  while(i<=10)
  {
synchronized(someLock) {
   arrayList.add(i);
}
   i++;
  }
  }
 });
 thread1.start();
 Thread thred2=new Thread(new Runnable() {
  public void run() {
     while(true)
     {
synchronized(someLock) {
   Iterator it=arrayList.iterator();
      while(it.hasNext())
      {
       System.out.println(it.next());
      }
}
     }
  }
 });
 thred2.start();
  }
 }

public class test
{
  public static void main(String[] args)
  {
   HelloThread hello=new HelloThread();
   hello.go();
  }
}

I'm not sure what you're trying to do, so I hope this doesn't break the functionality of your code.