2nd/10_Wiki/Topics/Domain_Programming/Topic_Java/Java_Arrays.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-arrays	Java Arrays	Programming_Language	draft	conceptual		자바 배열		B	0.9	2026-07-04	2026-07-04			java programming w3schools arrays	https://www.w3schools.com/java/java_arrays.asp

Java Arrays

🎯 한 줄 통찰 (One-line insight)

new TYPE[size] and the {...} literal shortcut cannot be combined (new String[4] {"Volvo",...} is illegal) — you must choose one of two modes: reserve empty slots to fill later, OR declare-and-populate at once, never both. [S1]

🧠 핵심 개념 (Core concepts)

• Declaration — String[] cars; declares an array variable of a type with []. [S1]
• Literal initialization — String[] cars = {"Volvo", "BMW", "Ford", "Mazda"};. [S1]
• Zero-based indexing — cars[0] is the first element. [S1]
• Element mutation — cars[0] = "Opel"; overwrites by index. [S1]
• .length — property (not a method call) returning element count. [S1]
• new keyword — new String[4] creates an empty fixed-size array to fill later; mutually exclusive with the literal shortcut in the same declaration. [S1]

🧩 추출된 패턴 (Extracted patterns)

• new + literal is illegal together — new String[4] {"Volvo", "BMW", "Ford", "Mazda"} doesn't compile; you either specify a size (new String[4]) OR values (new String[] {...} / the bare {...} shortcut), never both in one new expression. [S1]

📖 세부 내용 (Details)

• Access: String[] cars = {"Volvo", "BMW", "Ford", "Mazda"}; System.out.println(cars[0]); // Volvo. [S1]
• Mutation: cars[0] = "Opel"; // Now outputs Opel instead of Volvo. [S1]
• Length: System.out.println(cars.length); // 4. [S1]
• Empty-then-fill with new: String[] cars = new String[4]; cars[0] = "Volvo"; .... [S1]
• Equivalent forms: String[] cars = new String[] {"Volvo", "BMW", "Ford", "Mazda"}; vs. the shortcut String[] cars = {"Volvo", "BMW", "Ford", "Mazda"}; (most common). [S1]

⚖️ 모순 및 업데이트 (Contradictions & updates)

• new와 리터럴의 배타성: new String[4]와 리터럴 초기화를 동시에 쓸 수 없다는 점이 소스에서 명시적으로 강조됨. [S1]

🛠️ 적용 사례 (Applied in summary)

현재 발견된 실제 적용 사례가 없습니다 — 여러 값을 하나의 변수로 관리하는 기본 자료구조로, 이후 루프/다차원 배열의 기반이 된다. [S1]

💻 코드 패턴 (Code patterns)

Array declaration and index access (Java):

String[] cars = {"Volvo", "BMW", "Ford", "Mazda"};
System.out.println(cars[0]);  // Volvo
System.out.println(cars.length);  // 4

✅ 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 For Each Loop, Java Arrays Loop, Java Arrays Multi
• 참조 맥락: 여러 값을 하나의 변수로 관리하는 기본 자료구조 — Loop/Multi 챕터로 확장.

📚 출처 (Sources)

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

📝 변경 이력 (Change history)

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