2020-10-25

package act4_2;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;

public class TestIterator {
    public static void main(String[] args) {
        // create a list instance
        List<String> list = new ArrayList<>();
        
        // add some elements into the list
        list.add("red");
        list.add("green");
        list.add("blue");
        list.add("pink");
        
        // print all elements
        System.out.println("print all elements before removing 'blue'");
        Iterator<String> iter = list.iterator();
        while (iter.hasNext()) {
            System.out.println(iter.next());
        }
        
        // remove an element within the iterator loop
        iter = list.iterator();
        while (iter.hasNext()) {
            String element = iter.next();
            if (element.equals("blue")) {
                iter.remove();
                break;
            }
        }
        
        System.out.println("print all elements after removing 'blue'");
        iter = list.iterator();
        while (iter.hasNext()) {
            System.out.println(iter.next());
        }
        
        System.out.println("print all elements by ListIterator: forward");
        ListIterator<String> listIterator = list.listIterator();
        while (listIterator.hasNext()) {
            System.out.println(listIterator.next());
        }
        
        System.out.println("print all elements by ListIterator: backward");
        while (listIterator.hasPrevious()) {
            System.out.println(listIterator.previous());
        }
        
        System.out.println("replace 'pink' with 'yellow':");
        while (listIterator.hasNext()) {
            if (listIterator.next().equals("pink")) {
                listIterator.set("yellow");
                break;
            }
        }
        
        System.out.println("After replacing:");
        iter = list.iterator();
        while (iter.hasNext()) {
            System.out.println(iter.next());
        }
    }
}