2nd/10_Wiki/Topics/Topic_Programming/Topic_Java/Java_LinkedHashMap.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-linkedhashmap	Java LinkedHashMap	Programming_Language	draft	conceptual		자바 LinkedHashMap		B	0.89	2026-07-04	2026-07-04			java programming w3schools collections-framework linkedhashmap	https://www.w3schools.com/java/java_linkedhashmap.asp

Java LinkedHashMap

🎯 한 줄 통찰 (One-line insight)

LinkedHashMap completes the exact same three-way pattern seen in the Set hierarchy (HashSet/TreeSet/LinkedHashSet) — HashMap (no order, fastest), TreeMap (sorted, slowest), LinkedHashMap (insertion order, middle ground) — showing Java's Collections Framework applies this identical order/speed trade-off symmetrically across both Set and Map implementations. [S1]

🧠 핵심 개념 (Core concepts)

• LinkedHashMap — stores key-value pairs, preserving INSERTION order (not sorted order). [S1]
• Same API as HashMap/TreeMap — put(), get(), remove(), clear(), size(), keySet(), values(). [S1]
• Duplicate key handling — same as HashMap: re-putting an existing key overwrites its value silently. [S1]
• Performance — slightly slower than HashMap due to order tracking (same trade-off pattern as LinkedHashSet vs. HashSet). [S1]

📖 세부 내용 (Details)

• Insertion-order preservation: LinkedHashMap<String, String> capitalCities = new LinkedHashMap<>(); capitalCities.put("England", "London"); capitalCities.put("India", "New Dehli"); ... // {England=London, India=New Dehli, Austria=Wien, Norway=Oslo, USA=Washington DC} — insertion order preserved. [S1]
• Comparison table: HashMap (no order, faster random access) vs. LinkedHashMap (insertion order preserved, slightly slower). [S1]

⚖️ 모순 및 업데이트 (Contradictions & updates)

소스에서 모순되는 정보는 발견되지 않음.

🛠️ 적용 사례 (Applied in summary)

현재 발견된 실제 적용 사례가 없습니다 — 입력된 순서 그대로 국가-수도 목록을 유지해야 할 때 LinkedHashMap이 적합하다. [S1]

💻 코드 패턴 (Code patterns)

LinkedHashMap preserves insertion order (Java):

LinkedHashMap<String, String> capitalCities = new LinkedHashMap<>();
capitalCities.put("England", "London");
capitalCities.put("India", "New Dehli");
capitalCities.put("Austria", "Wien");
System.out.println(capitalCities);
// {England=London, India=New Dehli, Austria=Wien}

✅ 검증 상태 및 신뢰도

• 상태: draft
• 검증 단계: conceptual
• 출처 신뢰도: B (W3Schools — widely used educational reference, not a primary standards body)
• 신뢰 점수: 0.89
• 중복 검사 결과: 신규 생성 (New discovery)

🔗 지식 그래프 (Knowledge Graph)

• 상위/루트: Java Tutorial
• 관련 개념: Java HashMap, Java TreeMap, Java Iterator
• 참조 맥락: Map 구현체의 마지막 — Iterator 챕터로 이어짐(모든 자료구조 공통 순회 도구).

📚 출처 (Sources)

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

📝 변경 이력 (Change history)

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