2nd/10_Wiki/Topic_Programming/Topic_Java/Java_Iterator.md

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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-iterator	Java Iterator	Programming_Language	draft	conceptual		자바 이터레이터		B	0.9	2026-07-04	2026-07-04			java programming w3schools collections-framework iterator	https://www.w3schools.com/java/java_iterator.asp

Java Iterator

🎯 한 줄 통찰 (One-line insight)

Removing elements while looping REQUIRES an Iterator's own remove() method — the source explicitly warns that a for loop or for-each loop would NOT work correctly for conditional removal, since the collection changes size mid-loop; only Iterator.remove() is designed to safely mutate the collection during iteration. [S1]

🧠 핵심 개념 (Core concepts)

• Iterator — an object for looping through collections (ArrayList, HashSet, etc.); "iterating" = the technical term for looping. [S1]
• .iterator() — obtains an Iterator from any collection. [S1]
• hasNext() / next() — standard loop pattern: check then advance. [S1]
• remove() — Iterator-specific method that safely removes the current element DURING iteration. [S1]
• Unsafe alternative — for/for-each loops break when the collection's size changes mid-loop; only Iterator.remove() handles this correctly. [S1]

📖 세부 내용 (Details)

• Get iterator and print first: Iterator<String> it = cars.iterator(); System.out.println(it.next());. [S1]
• Full loop: while(it.hasNext()) { System.out.println(it.next()); }. [S1]
• Safe conditional removal: ArrayList<Integer> numbers = ...; Iterator<Integer> it = numbers.iterator(); while(it.hasNext()) { Integer i = it.next(); if(i < 10) { it.remove(); } }. [S1]

⚖️ 모순 및 업데이트 (Contradictions & updates)

• for/for-each 루프의 위험성: 컬렉션 순회 중 요소를 제거하려면 for 루프나 for-each 루프는 올바르게 동작하지 않는다는 점이 명시적으로 경고됨 — 반드시 Iterator.remove() 사용. [S1]

🛠️ 적용 사례 (Applied in summary)

현재 발견된 실제 적용 사례가 없습니다 — 10 미만의 숫자를 컬렉션에서 제거하는 예제가 순회 중 안전한 삭제의 표준 패턴이다. [S1]

💻 코드 패턴 (Code patterns)

Safely removing elements during iteration (Java):

ArrayList<Integer> numbers = new ArrayList<Integer>();
numbers.add(12); numbers.add(8); numbers.add(2); numbers.add(23);
Iterator<Integer> it = numbers.iterator();
while (it.hasNext()) {
    Integer i = it.next();
    if (i < 10) {
        it.remove(); // safe removal during iteration
    }
}

✅ 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 ArrayList, Java HashSet, Java For Each Loop, Java Algorithms
• 참조 맥락: 자료구조 공통 순회 도구 — Data Structures & Collections 섹션의 마지막, Advanced(알고리즘) 섹션으로 이어짐.

📚 출처 (Sources)

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

📝 변경 이력 (Change history)

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