我有以下代码
public class Test{
private static final String key = "key";
public static void main(String[] a){
ConcurrentHashMap<String,String > map = new ConcurrentHashMap<String,String>();
System.out.println(map.replace(key,"1"));
System.out.println(map.replace(key,"2"));
}
}
两次输出都为空。不应该是1秒吗?