2nd/10_Wiki/Topics/Domain_Programming/Topic_Java/Java_RegEx.md

id, title, category, status, verification_status, canonical_id, aliases, duplicate_of, source_trust_level, confidence_score, created_at, updated_at, review_reason, merge_history, tags, raw_sources, applied_in, github_commit

id	title	category	status	verification_status	canonical_id	aliases	duplicate_of	source_trust_level	confidence_score	created_at	updated_at	review_reason	merge_history	tags	raw_sources	applied_in	github_commit
java-regex	Java RegEx	Programming_Language	draft	conceptual		regular expressions 자바 정규표현식		B	0.88	2026-07-04	2026-07-04			java programming w3schools regex	https://www.w3schools.com/java/java_regex.asp

Java RegEx

🎯 한 줄 통찰 (One-line insight)

Java has no built-in Regular Expression type — like dates, regex requires importing java.util.regex (Pattern + Matcher classes), and the search flow is explicitly two-step: Pattern.compile() builds the pattern object first, then .matcher(text).find() runs the actual search against a specific string, decoupling "what to search for" from "where to search." [S1]

🧠 핵심 개념 (Core concepts)

• Regular expression — a sequence of characters forming a search pattern for text search/replace. [S1]
• java.util.regex package — required import; contains Pattern, Matcher, PatternSyntaxException. [S1]
• Pattern.compile(regex, flags) — builds the pattern; flags are optional (e.g. Pattern.CASE_INSENSITIVE). [S1]
• pattern.matcher(text) — returns a Matcher bound to a specific string. [S1]
• matcher.find() — returns true/false depending on whether the pattern matches. [S1]
• Bracket expressions — [abc] (any of a/b/c), [^abc] (none of a/b/c), [0-9] (digit range). [S1]
• Metacharacters — | (alternation), . (any char), ^/$ (start/end anchors), \d (digit), \s (whitespace), \b (word boundary), \uxxxx (Unicode). [S1]
• Quantifiers — n+, n*, n?, n{x}, n{x,y}, n{x,}. [S1]

📖 세부 내용 (Details)

• Basic case-insensitive search: Pattern pattern = Pattern.compile("w3schools", Pattern.CASE_INSENSITIVE); Matcher matcher = pattern.matcher("Visit W3Schools!"); boolean matchFound = matcher.find(); // true. [S1]
• Flags: Pattern.CASE_INSENSITIVE, Pattern.LITERAL (treats special chars as ordinary), Pattern.UNICODE_CASE (extends case-insensitivity beyond English). [S1]

⚖️ 모순 및 업데이트 (Contradictions & updates)

소스에서 모순되는 정보는 발견되지 않음.

🛠️ 적용 사례 (Applied in summary)

현재 발견된 실제 적용 사례가 없습니다 — 대소문자 구분 없이 특정 단어의 존재 여부를 검사하는 것이 정규표현식의 가장 기본적인 실전 활용이다. [S1]

💻 코드 패턴 (Code patterns)

Case-insensitive pattern search (Java):

import java.util.regex.Matcher;
import java.util.regex.Pattern;

Pattern pattern = Pattern.compile("w3schools", Pattern.CASE_INSENSITIVE);
Matcher matcher = pattern.matcher("Visit W3Schools!");
boolean matchFound = matcher.find(); // true

✅ 검증 상태 및 신뢰도

• 상태: draft
• 검증 단계: conceptual
• 출처 신뢰도: B (W3Schools — widely used educational reference, not a primary standards body)
• 신뢰 점수: 0.88
• 중복 검사 결과: 신규 생성 (New discovery)

🔗 지식 그래프 (Knowledge Graph)

• 상위/루트: Java Tutorial
• 관련 개념: Java Annotations, Java Strings, Java Threads
• 참조 맥락: 텍스트 검색/치환의 표준 도구 — 스레드(Threads) 챕터로 이어짐.

📚 출처 (Sources)

• [S1] W3Schools — Java Regular Expressions — https://www.w3schools.com/java/java_regex.asp

📝 변경 이력 (Change history)

• 2026-07-04: Initial draft synthesized from the W3Schools "Java Regular Expressions" page (Astra wiki-curation, P-Reinforce v3.1 format).