2nd/10_Wiki/Topic_Programming/Topic_Java/Java_Algorithms.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-algorithms	Java Algorithms	Programming_Language	draft	conceptual		Collections class algorithms 자바 알고리즘		B	0.88	2026-07-04	2026-07-04			java programming w3schools algorithms collections	https://www.w3schools.com/java/java_algorithms.asp

Java Algorithms

🎯 한 줄 통찰 (One-line insight)

Collections.binarySearch() REQUIRES the list to already be sorted — the example explicitly calls Collections.sort(names) immediately before binarySearch(), since binary search's speed advantage depends entirely on the data being in order; searching an unsorted list with it gives undefined/incorrect results. [S1]

🧠 핵심 개념 (Core concepts)

• Algorithm — a procedure to solve a problem (search, sort, manipulate data structures). [S1]
• Collections class — provides built-in algorithms in java.util, avoiding the need to hand-write them. [S1]
• Collections.binarySearch(list, key) — fast search, but requires a pre-sorted list. [S1]
• Collections.sort(list) / sort(list, reverseOrder()) — ascending/descending sort. [S1]
• Collections.max() / min() — largest/smallest element. [S1]
• Collections.shuffle() — randomly reorders elements. [S1]
• Collections.frequency(list, element) — counts occurrences of a value. [S1]
• Collections.swap(list, i, j) — swaps two elements by index. [S1]

📖 세부 내용 (Details)

• Binary search (must sort first): Collections.sort(names); int index = Collections.binarySearch(names, "Angie");. [S1]
• Max/min: Collections.max(numbers); Collections.min(numbers);. [S1]
• Shuffle: Collections.shuffle(cards);. [S1]
• Frequency: int count = Collections.frequency(fruits, "Banana");. [S1]
• Swap: Collections.swap(fruits, 0, 2); // Swap first and third element. [S1]

⚖️ 모순 및 업데이트 (Contradictions & updates)

• 정렬 선행 조건: binarySearch()는 리스트가 반드시 정렬되어 있어야 정확히 동작한다는 점이 예제에서 명시적으로 지켜짐. [S1]

🛠️ 적용 사례 (Applied in summary)

현재 발견된 실제 적용 사례가 없습니다 — 카드 셔플(Collections.shuffle)이나 과일 빈도 계산(frequency)이 실전 알고리즘 활용의 대표 사례다. [S1]

💻 코드 패턴 (Code patterns)

Sort-then-binarySearch pattern (Java):

ArrayList<String> names = new ArrayList<>();
names.add("Liam"); names.add("Jenny"); names.add("Kasper"); names.add("Angie");
Collections.sort(names); // required before binarySearch
int index = Collections.binarySearch(names, "Angie");

✅ 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 Sort List, Java Iterator, Java Advanced Sorting
• 참조 맥락: Collections 클래스의 내장 알고리즘 — 고급 정렬(Advanced Sorting) 챕터로 이어짐.

📚 출처 (Sources)

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

📝 변경 이력 (Change history)

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