2nd/10_Wiki/Topics/Domain_Programming/Topic_Java/Java_Enums.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-enums	Java Enums	Programming_Language	draft	conceptual		enum keyword 자바 열거형		B	0.9	2026-07-04	2026-07-04			java programming w3schools oop enums	https://www.w3schools.com/java/java_enums.asp

Java Enums

🎯 한 줄 통찰 (One-line insight)

Enums can have attributes and methods just like classes, but with one key restriction that defines their whole purpose — enum constants are always public, static, and final, meaning you can never create an object from an enum or override its values, only select from a fixed listed set. [S1]

🧠 핵심 개념 (Core concepts)

• enum — a special class representing a group of unchangeable constants. [S1]
• Naming convention — constants written in uppercase, comma-separated. [S1]
• Dot-syntax access — Level myVar = Level.MEDIUM;. [S1]
• Enum inside a class — enums can be nested inside a regular class. [S1]
• Switch compatibility — enums work naturally as switch expressions, with case labels matching constant names (no dot prefix in case labels). [S1]
• values() — built-in method returning an array of all enum constants, useful for looping. [S1]
• Constraints vs. classes — cannot instantiate objects from an enum; cannot extend other classes (but CAN implement interfaces). [S1]

📖 세부 내용 (Details)

• Basic enum: enum Level { LOW, MEDIUM, HIGH } ... Level myVar = Level.MEDIUM;. [S1]
• Switch on enum: switch(myVar) { case LOW: ...; case MEDIUM: System.out.println("Medium level"); break; case HIGH: ...; }. [S1]
• Loop via values(): for (Level myVar : Level.values()) { System.out.println(myVar); } // LOW MEDIUM HIGH. [S1]

⚖️ 모순 및 업데이트 (Contradictions & updates)

• 불변성 제약: enum 상수는 public, static, final이므로 객체 생성이 불가하고 값 재정의도 불가하다는 점이 명확히 구분됨. [S1]

🛠️ 적용 사례 (Applied in summary)

현재 발견된 실제 적용 사례가 없습니다 — 요일, 색상, 카드 덱처럼 값이 절대 바뀌지 않는 고정 집합을 표현할 때 사용된다. [S1]

💻 코드 패턴 (Code patterns)

Enum used in a switch statement (Java):

enum Level { LOW, MEDIUM, HIGH }
Level myVar = Level.MEDIUM;
switch (myVar) {
    case LOW: System.out.println("Low level"); break;
    case MEDIUM: System.out.println("Medium level"); break;
    case HIGH: System.out.println("High level"); break;
}

✅ 검증 상태 및 신뢰도

• 상태: draft
• 검증 단계: conceptual
• 출처 신뢰도: B (W3Schools — widely used educational reference, not a primary standards body)
• 신뢰 점수: 0.90
• 중복 검사 결과: 신규 생성 (New discovery)

🔗 지식 그래프 (Knowledge Graph)

• 상위/루트: Java Tutorial
• 관련 개념: Java Switch, Java Enum Constructor, Java Interface
• 참조 맥락: 고정 상수 집합 표현 — 생성자를 갖는 enum(Enum Constructor)으로 확장.

📚 출처 (Sources)

• [S1] W3Schools — Java Enums — https://www.w3schools.com/java/java_enums.asp

📝 변경 이력 (Change history)

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