久久久久久久久99久

One problem with the factory method pattern is that the creation of the class depends on the factory class, that is to say, if you want to expand the program, you must modify the factory class, which violates the closure principle. Therefore, from the design point of view, there are certain problems, how to solve them? We use the abstract factory mode to create multiple factory classes, so that once new functions need to be added, we can directly add new factory classes without modifying the previous code. Because the abstract factory is not very easy to understand, let's look at the diagram first, and then it is easier to understand with the code.(3) The principle of electric time relay is similar to that of clocks and watches. It is delayed by the internal motor driving the reduction gear to rotate. This kind of relay has high delay accuracy and wide delay range (0.4 ~ 72h), but its structure is complicated and its price is very expensive.四人一拍即合，决心合力伏妖，共同解决人界危机，拯救世间万物。一场正邪之战，就此展开......In 15 years, P2P interest rates were still very high at that time, with 20% and 30% everywhere. I didn't know what fear was. There were also 30 + and 40 + investors. Only when thunder came did they slowly regain their rationality.Int result = cal.calate (exp);