Map集合遍历

Map<String,String> map = new HashMap<String, String>();
map.put("1","java");
map.put("2","c");
map.put("3","go");

1、取值遍历
for(String key:map.keySet()){
System.out.println("key="+key+"and value=" +map.get(key));
}
2、Iterator遍历
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());
}
3、遍历所有的value值
for(String v:map.values()){
System.out.println("value= "+ v);
}
4、使用entrySet遍历
for(Map.Entry<String,String > entry:map.entrySet()){
System.out.println("key=" +entry.getKey() +" and value="+entry.getValue());
}
注意：大量数据时使用第4种方式效率高