java 集合和迭代器

import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;

public class Test2 {
    public static void main(String[] args) {
        //集合
        Collection<String> collection = new ArrayList<>();
        collection.add("a");
        collection.add("b");
        collection.add("c");
        collection.add("d");
        System.out.println(collection);
        collection.remove("b");
        System.out.println(collection);

        //迭代器
        Iterator<String> iterator = collection.iterator();
        while (iterator.hasNext()) {
            String next = iterator.next();
            System.out.println(next);
        }


        System.out.printf("hello,world");
    }
}