10. Iterators

import java.util.Iterator;
import java.util.LinkedList;
 
public class App {
 
    public static void main(String[] args) {
 
        LinkedList<String> animals = new LinkedList<String>();
 
        animals.add("fox");
        animals.add("cat");
        animals.add("dog");
        animals.add("rabbit");
         
        // "Old" way of iterating through lists (except that generics
        // didn't exist pre Java 5). This way is still an integral part
        // of Java; it allows you to remove items from the list
        // and also supports the "for each" syntax behind the scenes.
 
        Iterator<String> it = animals.iterator();
 
        while (it.hasNext()) {
            String value = it.next();
            System.out.println(value);
             
            if(value.equals("cat")) {
                it.remove();
            }
        }
 
        System.out.println();
         
        /*
         * If you want to add items to a list while iterating through
         * it, get a ListIterator using the .listIterator() method.
         * ListIterator also has a previous() method, allowing you to
         * "rewind" the iterator so that you can add items before
         * the current item.
         */
 
        // / Modern iteration, Java 5 and later; "for each" loop
 
        for (String animal : animals) {
            System.out.println(animal);
             
            // The following won't work; you need an iterator.
            // Throws ConcurrentModificationException
            // animals.remove(2);
        }
    }
 
}