迭代器

Iterator接口，具有两个方法：hasNext及next,hasNext用于判断是否有下一个元素，next用于获得下一个元素。

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

public class TestIterator {
    public static void main(String[] args) {
        List<String> list = new ArrayList<>();
        list.add("aa");
        list.add("bb");
        list.add("cc");

        for (Iterator<String> iter = list.iterator(); iter.hasNext();) {
            String temp = iter.next();
            System.out.println(temp);
        }
    }

}

        Map<String, String> map = new HashMap<>();
        map.put("A", "1");
        map.put("B", "2");
        map.put("C", "3");
        Set<Map.Entry<String, String>> entries = map.entrySet();
        for (Iterator<Map.Entry<String, String>> iter = entries.iterator(); iter.hasNext(); ) {
            Map.Entry<String, String> next = iter.next();
            System.out.println(next.getKey() + "--------------" + next.getValue());
        }