遍历HashMap取出所有的Key和Value

public class HashMapSet {
 public static void main(String [] ags){
  Map m = new HashMap();
  m.put("w", "111");
  m.put("h", "222");
  m.put("g", "333");
  m.put("d", "444");
  m.put("s", "555");

  System.out.println("--------------------遍历key和value----------------------");
  //entrySet()方法用于在获得关键字的同时也获得值该方法返回一个Map.Entry实例后的对象集
  //该方法和keySet()方法相比 keySet每次只获得关键字 获得关键字以后 再返回获得值 比较麻烦
  //同时Map.Entry方法 也提供了两个方法 getKey();getValue()
  for(Iterator iter = m.entrySet().iterator();iter.hasNext();){
    Map.Entry element = (Map.Entry)iter.next();
    Object strKey = element.getKey();
    Object strValue = element.getValue();

    System.out.println(strKey+"/"+strValue);
  }

  System.out.println();
  System.out.println("--------------------遍历整个HashMap----------------------");
  //Collection 类是Map和Set接口的父类
  Collection objs = m.entrySet();
  for (Iterator iterator=objs.iterator(); iterator.hasNext();){
   Object obj = iterator.next();
   System.out.println(obj);
  }

  System.out.println();
  System.out.println("--------------------遍历HashMap的key----------------------");
  Collection keys = m.keySet();
  for (Iterator iterator=keys.iterator(); iterator.hasNext();){
   Object key = iterator.next();
   System.out.println(key);
  }

  System.out.println();
  System.out.println("--------------------遍历HashMap的value----------------------");
  Collection values = m.values();
  for (Iterator iterator=values.iterator(); iterator.hasNext();){
   Object value = iterator.next();
   System.out.println(value);
  }
 }
}