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75 lines
3.7 KiB
Markdown
75 lines
3.7 KiB
Markdown
---
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id: java-regex
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title: "Java RegEx"
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category: "Programming_Language"
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status: "draft"
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verification_status: "conceptual"
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canonical_id: ""
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aliases: ["regular expressions", "자바 정규표현식"]
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duplicate_of: ""
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source_trust_level: "B"
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confidence_score: 0.88
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created_at: 2026-07-04
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updated_at: 2026-07-04
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review_reason: ""
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merge_history: []
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tags: ["java", "programming", "w3schools", "regex"]
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raw_sources: ["https://www.w3schools.com/java/java_regex.asp"]
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applied_in: []
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github_commit: ""
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---
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# [[Java RegEx]]
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## 🎯 한 줄 통찰 (One-line insight)
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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]
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## 🧠 핵심 개념 (Core concepts)
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- **Regular expression** — a sequence of characters forming a search pattern for text search/replace. [S1]
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- **`java.util.regex` package** — required import; contains `Pattern`, `Matcher`, `PatternSyntaxException`. [S1]
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- **`Pattern.compile(regex, flags)`** — builds the pattern; flags are optional (e.g. `Pattern.CASE_INSENSITIVE`). [S1]
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- **`pattern.matcher(text)`** — returns a `Matcher` bound to a specific string. [S1]
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- **`matcher.find()`** — returns true/false depending on whether the pattern matches. [S1]
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- **Bracket expressions** — `[abc]` (any of a/b/c), `[^abc]` (none of a/b/c), `[0-9]` (digit range). [S1]
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- **Metacharacters** — `|` (alternation), `.` (any char), `^`/`$` (start/end anchors), `\d` (digit), `\s` (whitespace), `\b` (word boundary), `\uxxxx` (Unicode). [S1]
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- **Quantifiers** — `n+`, `n*`, `n?`, `n{x}`, `n{x,y}`, `n{x,}`. [S1]
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## 📖 세부 내용 (Details)
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- Basic case-insensitive search: `Pattern pattern = Pattern.compile("w3schools", Pattern.CASE_INSENSITIVE); Matcher matcher = pattern.matcher("Visit W3Schools!"); boolean matchFound = matcher.find(); // true`. [S1]
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- Flags: `Pattern.CASE_INSENSITIVE`, `Pattern.LITERAL` (treats special chars as ordinary), `Pattern.UNICODE_CASE` (extends case-insensitivity beyond English). [S1]
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## ⚖️ 모순 및 업데이트 (Contradictions & updates)
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소스에서 모순되는 정보는 발견되지 않음.
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## 🛠️ 적용 사례 (Applied in summary)
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현재 발견된 실제 적용 사례가 없습니다 — 대소문자 구분 없이 특정 단어의 존재 여부를 검사하는 것이 정규표현식의 가장 기본적인 실전 활용이다. [S1]
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## 💻 코드 패턴 (Code patterns)
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Case-insensitive pattern search (Java):
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```java
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import java.util.regex.Matcher;
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import java.util.regex.Pattern;
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Pattern pattern = Pattern.compile("w3schools", Pattern.CASE_INSENSITIVE);
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Matcher matcher = pattern.matcher("Visit W3Schools!");
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boolean matchFound = matcher.find(); // true
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```
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## ✅ 검증 상태 및 신뢰도
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- **상태:** draft
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- **검증 단계:** conceptual
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- **출처 신뢰도:** B (W3Schools — widely used educational reference, not a primary standards body)
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- **신뢰 점수:** 0.88
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- **중복 검사 결과:** 신규 생성 (New discovery)
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## 🔗 지식 그래프 (Knowledge Graph)
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- **상위/루트:** [[Java Tutorial]]
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- **관련 개념:** [[Java Annotations]], [[Java Strings]], [[Java Threads]]
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- **참조 맥락:** 텍스트 검색/치환의 표준 도구 — 스레드(Threads) 챕터로 이어짐.
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## 📚 출처 (Sources)
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- [S1] W3Schools — Java Regular Expressions — https://www.w3schools.com/java/java_regex.asp
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## 📝 변경 이력 (Change history)
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- 2026-07-04: Initial draft synthesized from the W3Schools "Java Regular Expressions" page (Astra wiki-curation, P-Reinforce v3.1 format).
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