배우기를 멈추는 사람은 20세건 80세건 늙은 것이다.

public static void delete(String name) { AdminClient client = AdminClient.create(properties()); DeleteTopicsResult deleteTopicsResult = client.deleteTopics(Collections.singletonList(name)); while (!deleteTopicsResult.all().isDone()) { } } https://stackoverflow.com/questions/54140543/delete-topic-not-working-for-kafka-java-client-2-1-0/70729759#70729759 delete topic not working for kafka java cli..

https://stackoverflow.com/questions/90002/what-is-a-reasonable-code-coverage-for-unit-tests-and-why What is a reasonable code coverage % for unit tests (and why)? If you were to mandate a minimum percentage code-coverage for unit tests, perhaps even as a requirement for committing to a repository, what would it be? Please explain how you arrived at your ans... stackoverflow.com https://jamie95.t..

session.timeout.ms heartbeat.interval.ms max.poll.interval.ms max.poll.records enable.auto.commit auto.commit.interval.ms auto.offset.reset https://dev-jj.tistory.com/entry/Kafka-%EA%B0%99%EC%9D%80%EB%A9%94%EC%8B%9C%EC%A7%80%EB%A5%BC-%EB%B0%98%EB%B3%B5%EC%A0%81%EC%9C%BC%EB%A1%9C-%EC%86%8C%EB%B9%84%ED%96%88%EB%8D%98-%EB%A6%AC%EB%B0%B8%EB%9F%B0%EC%8B%B1-%EC%9D%B4%EC%8A%88-%ED%95%B4%EA%B2%B0-MAX-PO..

ResultSetMetaData metaData = resultSet.getMetaData(); int count = metaData.getColumnCount(); //number of column String columnName[] = new String[count]; for (int i = 1; i

@Profile("prd") // 운영시에만 사용하겠다. @Profile("!prd") // 운영이 아닌 모든곳에서 사용하겠다. @Profile({"local", "dev"}) // local과 dev phase에 사용하겠다. @Value("${spring.profiles.active}") private String activeProfile; @Value("${spring.profiles.active:}") private String activeProfile; String profile = System.getProperty("spring.profiles.active; https://oingdaddy.tistory.com/393 Springboot Profile 설정방법 및 가져오기 프로젝트를 진행 시 p..

public static void create(String name) { AdminClient client = AdminClient.create(properties()); NewTopic topic = new NewTopic( name, (int)conf().get("partition"), Short.parseShort(String.valueOf(conf().get("replication.factor")))); client.createTopics(Collections.singleton(topic)); client.close(); } https://stackoverflow.com/questions/64077406/why-is-adminclient-not-failing-when-creating-a-topic..

https://stackoverflow.com/questions/20414804/java-backslash-encode-special-characters-like-quote-tab-newline-backslash-to Java backslash encode special characters like quote, tab, newline, backslash to make parseable I'm writing Java that gets strings like "C:\Temp\file.txt" and generates C source code containing those strings, the code will be compiled later. So I need to render the strings in ..

### char - 고정길이 - 고정길이 필드 사용 ### varchar, varchar2 - 가변길이 - 길이가 몇인지 계산 (추가 연산 비용) https://kasckasc.tistory.com/entry/Oracle-CHAR-VARCHAR-VARCHAR2-%EC%B0%A8%EC%9D%B4 [Oracle] CHAR, VARCHAR, VARCHAR2 차이 데이터베이스 데이터 유형 및 CHAR와 VARCHAR 비교 데이터 유형은 데이터베이스의 테이블에 특정 자료를 입력할 때, 그 자료를 받아들일 공간을 자료의 유형별로 나누는 기준이다. 따라서 선언한 kasckasc.tistory.com https://mozi.tistory.com/229 [DBA] 데이터타입 CHAR 와 VARCHAR 중 어느것을 써야할..

@Profile(value = {"swagger"}) @Configuration @EnableSwagger2 public class SwaggerConfiguration { ... } import org.apache.commons.lang3.StringUtils; import org.springframework.context.annotation.Profile; import org.springframework.http.HttpStatus; import org.springframework.http.ResponseEntity; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.GetMap..

brew install mysql mysql.server start http://meonggae.blogspot.com/2017/03/db-mac-mysql-1-error-2002-hy000-cant.html [db] mac에서 mysql환경설정 셋팅하기 1편 - 설치 및 접속, ERROR 2002 (HY000) : Can't connect to local MySQL server db, mysql, error2002 meonggae.blogspot.com

DatabaseMetaData dbm = con.getMetaData(); // check if "employee" table is there ResultSet tables = dbm.getTables(null, null, "employee", null); if (tables.next()) { // Table exists } else { // Table does not exist } https://stackoverflow.com/questions/2942788/check-if-table-exists Check if table exists I have a desktop application with a database embedded in it. When I execute my program I need ..

ResultSet rs = stmt.executeQuery("SELECT a, b, c FROM TABLE2"); ResultSetMetaData rsmd = rs.getMetaData(); String name = rsmd.getColumnName(1); https://stackoverflow.com/questions/696782/retrieve-column-names-from-java-sql-resultset Retrieve column names from java.sql.ResultSet With java.sql.ResultSet is there a way to get a column's name as a String by using the column's index? I had a look thr..

https://stackoverflow.com/questions/26544091/checking-if-type-list-in-python Checking if type == list in python I may be having a brain fart here, but I really can't figure out what's wrong with my code: for key in tmpDict: print type(tmpDict[key]) time.sleep(1) if(type(tmpDict[key])==list): ... stackoverflow.com https://stackoverflow.com/questions/25231989/how-to-check-if-a-variable-is-a-dictio..

https://www.w3schools.com/sql/sql_datatypes.asp SQL Data Types for MySQL, SQL Server, and MS Access W3Schools offers free online tutorials, references and exercises in all the major languages of the web. Covering popular subjects like HTML, CSS, JavaScript, Python, SQL, Java, and many, many more. www.w3schools.com

https://kim-jong-hyun.tistory.com/32 [JAVA] - JSON 데이터(object, array)를 다뤄보기 2장에서는 JAVA에서 JSON 데이터로 HTTP 통신을 해보는 시간을 가졌는데 이번에는 직접 JSON 데이터를 다뤄보는 시간을 가져보자 JSON 데이터를 다루기 위한 라이브러리와 HTTP통신하는 예제는 아래링 kim-jong-hyun.tistory.com

package util; import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; import java.util.Map; import java.util.Random; public class RandomUtils { private static class SHA256 { public static String encrypt(String text) { MessageDigest md = null; try { md = MessageDigest.getInstance("SHA-256"); } catch (NoSuchAlgorithmException e) { e.printStackTrace(); } md.update(text.ge..

CREATE USER IF NOT EXISTS 'akm'@'localhost' IDENTIFIED BY 'akm' PASSWORD EXPIRE NEVER; GRANT ALL PRIVILEGES ON akm.* TO 'akm'@'localhost'; FLUSH PRIVILEGES; https://www.lesstif.com/dbms/mysql-24445981.html MySQL 데이타베이스와 사용자 계정 생성하기 설치후 최초 root 암호를 변경할 경우 아래 구문 사용 www.lesstif.com

import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; public class SHA256 { public String encrypt(String text) throws NoSuchAlgorithmException { MessageDigest md = MessageDigest.getInstance("SHA-256"); md.update(text.getBytes()); return bytesToHex(md.digest()); } private String bytesToHex(byte[] bytes) { StringBuilder builder = new StringBuilder(); for (byte b : byte..

URL sqlScriptUrl = MyServletContextListener.class .getClassLoader().getResource("sql/script.sql"); https://stackoverflow.com/questions/19414453/how-to-get-resources-directory-path-programmatically How to get resources directory path programmatically I have the following directory layout: src main java resources sql (scripts for database) spring (configuration) webapp Within a ServletContextListe..

public static Writer makeOrcWriter(String path, Class clazz) throws IOException { FileUtils.delete(path); Configuration conf = new Configuration(false); FileSystem fs = FileSystem.get(conf); return OrcFile.createWriter(new Path(path), OrcFile.writerOptions(conf) .inspector(ObjectInspectorFactory.getReflectionObjectInspector(clazz, ObjectInspectorFactory.ObjectInspectorOptions.JAVA)) .fileSystem(..

public static List files(String dirname) { if (dirname == null) { return Collections.emptyList(); } File dir = new File(dirname); if (!dir.exists()) { return Collections.emptyList(); } if (!dir.isDirectory()) { return Collections.singletonList(file(dirname)); } return Arrays.stream(Objects.requireNonNull(dir.listFiles())) .collect(Collectors.toList()); } https://stackoverflow.com/questions/18446..

http://junit.sourceforge.net/javadoc/org/junit/Assert.html Assert (JUnit API) clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait junit.sourceforge.net

https://stackoverflow.com/questions/2674554/how-do-you-know-a-variable-type-in-java How do you know a variable type in java? Let's say I declare a variable: String a = "test"; And I want to know what type it is, i.e., the output should be java.lang.String How do I do this? stackoverflow.com

https://stackoverflow.com/questions/13357760/mysql-create-user-if-not-exists mysql create user if not exists I have a query to check mysql users list for create new user. IF (SELECT EXISTS(SELECT 1 FROM `mysql`.`user` WHERE `user` = '{{ title }}')) = 0 THEN CREATE USER '{{ title }}'@'localhost' IDENT... stackoverflow.com

https://stackoverflow.com/questions/35592034/how-do-i-add-database-name-with-hyphen-character-using-script-in-ubuntu/35592181 how do i add database name with hyphen character using script in ubuntu I've tried using this code in a script but it just created what is inside the backtick. In this example, "echo "table-db"" was created in the database. It didn't create the name of the folder with .....

1. 이더리움이란 무엇인가? 이더리움(Ethereum) 월드 컴퓨터(World Computer) 결정론적(Deterministic) 한정되지 않은 머신(Unbounded State Machine) 전역적으로(Globally) 싱글톤(Singleton) 가상머신(Virtual Machine) 스마트 컨트랙트(smart contract) 이더(ether): 화폐; 실행 자원 비용을 측정하고 제한한다. 비트코인과의 비교 피어투피어(peer-to-peer) 네트워크 상태 변경을 동기화하는 비잔틴 결함 허용 합의(Byzantine fault-tolerant consensus) 알고리즘(작업증명 블록체인) 디지털 서명과 해시 디지털 화폐 (이더) 같은 암호학 기반 기술의 사용 등이 그런 공통 요소에 해당한다. 유틸..

https://programmer93.tistory.com/64 Spring boot logging - @Slf4j 어노테이션 사용법 - 삽질중인 개발자 개발을 하거나 운영을 하는 상황에서 LOGGING 은 아주 중요하다. Spring boot에서는 로그를 남기는 방법이 많이 있다. 그중 가장 편하게 사용되는 @Slf4j 어노테이션을 알아보자. SLF4J 란? 로깅에 대한 programmer93.tistory.com

https://underflow101.tistory.com/22#recentComments [통신 이론] MQTT, MQTT Protocol (MQTT 프로토콜) 이란? - 1 (이론편) 이 론 MQTT(Message Queueing Telemetry Transport)는 2016년 국제 표준화 된 (ISO 표준 ISO/IEC PRF 20922) 발행-구독(Publish-Subscribe) 기반의 메시지 송수신 프로토콜이다. 작은 코드 공간이 필요하거나 네.. underflow101.tistory.com

@Cacheable(value = "devices", key = "#hardwareId", unless = "#result == null") public Device get(String hardwareId) @CachePut(value ="devices", key= "#hardwardId", unless = "#result == null") public Device update(String hardwareId) https://stackoverflow.com/questions/48945484/java-ehcache-how-to-replace-members Java ehCache, how to replace members I have a simple method that I have annotated for..