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Antigravity Agent e9cbf23ab5 docs(10_Wiki): Dev 폴더 누락분 반영 — Topic_Programming으로 통합

이전 재구성 작업에서 Dev/ 폴더가 누락되었던 것을 반영.

- Dev/Topic_Programming(중첩 폴더, 78개)은 Dev 자체 최상위 폴더들
  (Architecture/Conventions/Engineering_Intelligence 등)과 완전 중복이라 제거.
- Dev 최상위 엔지니어링 지식 폴더(Architecture/Conventions/Engineering_Intelligence/
  Failure_Library/Generalized_Principles/Language/Pattern_Catalog/Platform_Guides/
  Subsystems, 77개)는 이미 Topic_Programming/Topic_Programming에 더 최신 버전이
  존재해 중복 제거(고유 콘텐츠 1개는 예외 처리하여 이동 보존).
- Dev의 W3Schools 언어 튜토리얼 폴더(Topic_C/CPP/CSS/CSharp/HOWTO/HTML/Java/
  JavaScript/PHP/Python/SQL/W3CSS, 1201개)는 전부 Topic_Programming 하위로 이동.
- 에이전트 운영 상태(.astra/docs)는 그대로 유지, 콘텐츠 폴더만 정리.
- Topic_Programming 최종 문서 수: 2784 → 3985.

2026-07-05 00:39:13 +09:00

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title

Java Files Write

🎯 한 줄 통찰 (One-line insight)

FileWriter OVERWRITES a file by default — appending requires explicitly passing true as a SECOND constructor argument (new FileWriter("filename.txt", true)), which is easy to miss since the single-argument constructor silently discards existing content. [S1]

🧠 핵심 개념 (Core concepts)

FileWriter — the simplest class for writing text to a file. [S1]
.write(text) + .close() — writes then must manually close (or use try-with-resources). [S1]
Default behavior: overwrite — an existing file's content is replaced unless append mode is used. [S1]
Append mode — pass true as the second constructor argument: new FileWriter("filename.txt", true). [S1]
Auto-creation — if the file doesn't exist, Java creates it before appending. [S1]
Alternative write classes — FileWriter (easiest, basic text), BufferedWriter (faster, better for large files), FileOutputStream (best for binary data). [S1]

📖 세부 내용 (Details)

Basic write with manual close: FileWriter myWriter = new FileWriter("filename.txt"); myWriter.write("Files in Java might be tricky, but it is fun enough!"); myWriter.close();. [S1]
Try-with-resources (auto-close): try (FileWriter myWriter = new FileWriter("filename.txt")) { myWriter.write("..."); } catch (IOException e) {...}. [S1]
Append mode: try (FileWriter myWriter = new FileWriter("filename.txt", true)) { myWriter.write("\nAppended text!"); }. [S1]

⚖️ 모순 및 업데이트 (Contradictions & updates)

기본 동작이 덮어쓰기: 추가(append)하려면 반드시 두 번째 인자로 true를 전달해야 한다는 점이 강조됨. [S1]

🛠️ 적용 사례 (Applied in summary)

현재 발견된 실제 적용 사례가 없습니다 — 로그 파일에 내용을 추가하는 등 append 모드는 실전에서 자주 쓰이는 패턴이다. [S1]

💻 코드 패턴 (Code patterns)

Append mode via the two-argument FileWriter constructor (Java):

try (FileWriter myWriter = new FileWriter("filename.txt", true)) { // true = append
    myWriter.write("\nAppended text!");
    System.out.println("Successfully appended to the file.");
} catch (IOException e) {
    System.out.println("An error occurred.");
}

✅ 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 Files Create, Java Files Read, Java BufferedWriter, Java FileOutputStream
참조 맥락: 파일에 텍스트 쓰기 — Read 챕터로 이어지며, BufferedWriter/FileOutputStream은 후속 챕터에서 심화.

📚 출처 (Sources)

[S1] W3Schools — Java Write To Files — https://www.w3schools.com/java/java_files_write.asp

📝 변경 이력 (Change history)

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

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