2nd/10_Wiki/Dev/Topic_Java/Java_Data_Structures.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-data-structures	Java Data Structures	Programming_Language	draft	conceptual		자바 자료구조 개요		B	0.88	2026-07-04	2026-07-04			java programming w3schools data-structures	https://www.w3schools.com/java/java_data_structures.asp

Java Data Structures

🎯 한 줄 통찰 (One-line insight)

The choice between ArrayList/HashSet/HashMap comes down to a single 3-column decision table (order-kept? duplicates-allowed? best-for) — order+duplicates → ArrayList, uniqueness → HashSet, key-based lookup → HashMap, giving a fast heuristic before diving into each structure's details. [S1]

🧠 핵심 개념 (Core concepts)

• Data structure — a way to store/organize data efficiently; arrays are the simplest example. [S1]
• ArrayList — resizable array; keeps insertion order; allows duplicates; access by index. [S1]
• HashSet — every element unique; adding a duplicate is silently ignored; no fixed order. [S1]
• HashMap — stores key-value pairs for fast lookup by key; keys unique, values can duplicate. [S1]
• Iterator — a standard way to loop through any data structure via hasNext()/next(). [S1]

📖 세부 내용 (Details)

• ArrayList: ArrayList<String> cars = new ArrayList<String>(); cars.add("Volvo"); cars.add("BMW"); .... [S1]
• HashSet dedup: HashSet<String> cars = new HashSet<String>(); cars.add("BMW"); cars.add("BMW"); // duplicate ignored. [S1]
• HashMap key-value: HashMap<String, String> capitalCities = new HashMap<String, String>(); capitalCities.put("England", "London"); .... [S1]
• Iterator loop: Iterator<String> it = cars.iterator(); while(it.hasNext()) { System.out.println(it.next()); }. [S1]
• Comparison table: ArrayList (ordered, duplicates OK, index access), HashSet (unique, no order, fast checks), HashMap (key-value, no order, fast key lookup). [S1]

⚖️ 모순 및 업데이트 (Contradictions & updates)

소스에서 모순되는 정보는 발견되지 않음.

🛠️ 적용 사례 (Applied in summary)

현재 발견된 실제 적용 사례가 없습니다 — 국가-수도 매핑(HashMap)이 키 기반 조회의 대표 예시다. [S1]

💻 코드 패턴 (Code patterns)

Quick comparison: ArrayList, HashSet, HashMap (Java):

ArrayList<String> cars = new ArrayList<String>(); // ordered, duplicates OK
HashSet<String> uniqueCars = new HashSet<String>(); // unique only
HashMap<String, String> capitalCities = new HashMap<String, String>(); // key-value

✅ 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 Collections, Java List, Java Set, Java Map, Java Iterator
• 참조 맥락: 자료구조 전체 섹션의 개념적 도입부 — Collections Framework 챕터로 이어짐.

📚 출처 (Sources)

• [S1] W3Schools — Java Data Structures — https://www.w3schools.com/java/java_data_structures.asp

📝 변경 이력 (Change history)

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