//Map的四种遍历方法

//Map不能直接遍历 ，只能通过遍历Key与Value间接遍历

public static void main(String[] args) {

Map<String,String> map = new HashMap<String,String>();
map.put("1","value1");
map.put("2","value2");
map.put("3","value3");

//第一种：普遍使用，二次取值
System.out.println("通过Map.keySet遍历key和value：");
for (String key : map.keySet()) {
System.out.println("key= "+ key + " and value= " + map.get(key));
}

//第二种
System.out.println("通过Map.entrySet使用iterator遍历key和value：");
Iterator<Map.Entry<String,String>> it = map.entrySet().iterator();
while (it.hasNext()) {
Map.Entry<String,String> entry = it.next();
System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());
}

//第三种：推荐，尤其是容量大时
System.out.println("通过Map.entrySet遍历key和value");
for (Map.Entry<String,String> entry : map.entrySet()) {
System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());
}@H_403_43@@H_403_43@

//第四种
System.out.println("通过Map.values()遍历所有的value，但不能遍历key");
for (String v : map.values()) {
System.out.println("value= " + v);
}
}@H_403_43@