map集合转set集合

import java.util.*;

//Map集合的迭代器输出，先将Map集合变为Set集合，再使用Iterator迭代器
public class Java_collection {
 public static void main(String[] args) {
  Map<Integer, String> map = new HashMap<>();
  map.put(1, "张三");
  map.put(2, "李四");
  map.put(3, "王五");
  //输出Map集合
  //1.Map -> Set
  Set<Map.Entry<Integer, String>> set = map.entrySet();

  //2.取得Set接口迭代器
  Iterator<Map.Entry<Integer, String>> iterator = set.iterator();

  //3.迭代输出
  while (iterator.hasNext()) {
   Map.Entry<Integer, String> entry = iterator.next();
   System.out.println(entry.getKey() + "=" + entry.getValue());
  }

  List<Integer> list = new ArrayList<>();
  Collections.addAll(list,1,3,5,4,7,6,9);

 }
}