Thread is not working properly (synchronization)

Question

When I run this code, the output is "something is added" and then infinite loop ...

My program should print:

something is added

something is printed

I don't understand why the program can not exit while loop

import java.util.LinkedList;
public class Test {
static LinkedList<String> list = new LinkedList<String>();
public static void main(String[] args) {
    new Thread(new Runnable() {

        @Override
        public void run() {
            while(list.isEmpty()); // here is the loop
            System.out.println("something is printed"+list.get(0));
        }
    }).start(); 
    new Thread(new Runnable() {

        @Override
        public void run() {
            try{
                Thread.sleep(200);
                list.add("something");
                System.out.println("something is added");
            }catch (Exception e) {}
        }
    }).start(); 
  }
}

I am looking for solution and explanation

Thanks A lot

Answer 1

In order for threads to communicate and share data safely, they have to be properly synchronized. The simplest way to do that in your example is to wrap your list in a synchronized wrapper:

static List<String> list = Collections.synchronizedList(new LinkedList<>());