Yyangbongsooinyangbongsoo.hashnode.dev·May 15, 2022 · 4 min readThe meaning of the Optional form (Monad)I don't deal with the exact concept of Monad, but try to look at the form used by Java Optional from a Monad application perspective. Monad has a variety of applications and Optional is one of them (Optional are also called maybe monad). The terms ...00
Yyangbongsooinyangbongsoo.hashnode.dev·May 8, 2022 · 2 min readJava Date format compatibleIf we make java.util.Date object, basically log format is below. Sun May 08 18:03:23 KST 2022 Our team has an old system that is more than 10 years old so we are developing for renewal. The legacy program log format likes above. But We have to make s...00
Yyangbongsooinyangbongsoo.hashnode.dev·Apr 30, 2022 · 1 min readSLF4J Error Log FormatVariable s has string value. If I put that variable in Integer.valueOf method, I must encounter NumberFormatException. But It's not important. I just want to make exception. Let's see the below code. I can log variable s and exception e together usin...00
Yyangbongsooinyangbongsoo.hashnode.dev·Apr 24, 2022 · 1 min readBeware of using spring WebClient(Episode7)This episode story is simple. If we receive response that is list type, we can use flatMapIterable operator(finally return type is Flux). Sometimes, I found the Mono<List<T>> type. public Flux<String> getData() { return this.webClient.get() ...00
Yyangbongsooinyangbongsoo.hashnode.dev·Apr 17, 2022 · 2 min readBeware of using spring WebClient(Episode6)Let's imagine we received the WebClient response data and then binding to ResponseDto. Message value in ResponseDto can be null. public class ResponseDto { private String id; @Nullable private String message; public String getMessag...00
