Design a code to handle error codes
I have to say that the question examined is of great help to my programming concept.
This question is actually a question I encountered during the interview. The main thing is to examine the engineering ability, but at the time I only thought about using the table to drive the optimization. As a result, the range of the error code could not be recorded, and I did not think of it. However, the interviewer gave a hint, saying that the time complexity may not be O(N), so let's use the configuration file to solve this problem.
请补全这个函数String getInfo(int errCode)，输入错误码返回错误信息，比如：
错误代码1，用户名错误；
错误代码2，密码错误；
错误代码10-100，数据库错误；
错误代码200-1000，文件找不到错误。
要求这个函数要使修改错误码和错误信息时尽可能少修改代码（代码可维护）
We can abstract the error code into a class, use two boundaries to represent the upper and lower boundaries of the error code, and then compare it with the error code information read from the configuration file or the network to obtain the error code field. The time complexity is O(N ), but the reusability of the code is greatly improved.
/**
* 请补全这个函数String getInfo(int errCode)，输入错误码返回错误信息，比如：
* 错误代码1，用户名错误；
* 错误代码2，密码错误；
* 错误代码10-100，数据库错误；
* 错误代码200-1000，文件找不到错误。
* 要求这个函数要使修改错误码和错误信息时尽可能少修改代码（代码可维护）
*/
public class ErrCodeHelper {
/**
* 实现思路，把错误信息写在配置文件，或者从网络读取错误信息
*/
public static List<ErrCode> errCodes;
static class ErrCode{
public int min;
public int max;
public String errInfo;
public ErrCode(int min, int max, String errInfo) {
this.min = min;
this.max = max;
this.errInfo = errInfo;
}
}
public static String getInfo(int errCode){
String errInfo=null;
try {
errInfo=getInfo(errCode,loadErrCodeList());
} catch (Exception e) {
e.printStackTrace();
}
return errInfo;
}
public static String getInfo(int errCode, List<ErrCode> errCodeList) throws Exception {
if(errCodeList==null||errCodeList.isEmpty()){
throw new Exception("ErrCode List Error");
}
for (ErrCode code:errCodeList){
if(errCode>=code.min&&errCode<=code.max){
return code.errInfo;
}
}
throw new Exception("ErrCode Not Found Exception");
}
public static List<ErrCode> loadErrCodeList(){
if(errCodes==null){
//read from disk or network
errCodes=new LinkedList<>();
}
return errCodes;
}
}