[Ch15b] A test to see what's happening under the covers with CopyOnWriteArrayList

package ch15b;

import org.junit.jupiter.api.Test;

import java.util.Iterator;

import java.util.concurrent.CopyOnWriteArrayList;

public class COWALTest {

  @Test

  void doIGetTheSameIterator() {

    CopyOnWriteArrayList<String> list = new CopyOnWriteArrayList<>();

    list.add("Hi");

    list.add("There");

    list.add("Everyone");

    // use the debugger to inspect these objects

    // the iterators are different instances (of course, because they will track different iterations of the data)

    // but the snapshot of the list that they iterate over are the same array

    System.out.println(list.iterator());

    System.out.println(list.iterator());

  }

  @Test

  void showMeTheNewArrayAfterWriting() {

    CopyOnWriteArrayList<String> list = new CopyOnWriteArrayList<>();

    list.add("Hi");

    list.add("There");

    list.add("Everyone");

    // breakpoint here

    // initial iterator/backing array

    System.out.println(list.iterator());

    Iterator<String> iterator = list.iterator();

    System.out.println(iterator);

    // write to the list

    list.add("Hey I'm new here");

    // breakpoint here. Take a look at the backing array on a new iterator

    System.out.println(list.iterator());

  }

}