集合框架_集合的使用步骤图解、迭代器的原理及源码解析

public iterface Iterator{
    public abstract boolean hasNext();
    public abstract Object next();
}

public interface Iterable {
    Iterator iterator();
}

public iterface Collection extends Iterable{
    Iterator iterator();
}

public iterface List extends Collection{
    Iterator iterator();
}

public class ArrayList implements List{
     public Iterator iterator() {
        return new Itr();
     }
     
     private class Itr implements Iterator {
        public boolean hasNext(){}
        public Object next(){}
     }
}


Collection c = new ArrayList();
c.add("hello");
c.add("world");
c.add("java");
Iterator it = c.iterator(); //new Itr();
while(it.hasNext()){
    String s = (String)it.next(); 
    System.out.println(s);
}