2nd/10_Wiki/Dev/Topic_Java/Java_Errors.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-errors	Java Errors	Programming_Language	draft	conceptual		자바 에러 유형		B	0.9	2026-07-04	2026-07-04			java programming w3schools errors	https://www.w3schools.com/java/java_errors.asp

Java Errors

🎯 한 줄 통찰 (One-line insight)

Logical errors are explicitly called "hardest to find" because the program compiles AND runs without crashing — it just produces wrong results (e.g., x - y instead of x + y), meaning no error message points you to the bug; only testing against expected output reveals it. [S1]

🧠 핵심 개념 (Core concepts)

• Compile-time error — detected by the compiler, prevents the code from running (syntax/type issues). [S1]
• Runtime error — occurs while running, often causes crashes (e.g., division by zero, out-of-bounds access). [S1]
• Logical error — code runs and produces output, but the output is wrong; hardest category to detect. [S1]
• Good habits — meaningful variable names, reading error messages for line numbers, checking for missing semicolons/braces, watching for typos. [S1]

📖 세부 내용 (Details)

• Missing semicolon: int x = 5 System.out.println(x); // error: ';' expected. [S1]
• Undeclared variable: System.out.println(myVar); // cannot find symbol: variable myVar. [S1]
• Mismatched types: int x = "Hello"; // incompatible types: String cannot be converted to int. [S1]
• Division by zero: int x = 10; int y = 0; int result = x / y; // ArithmeticException: / by zero. [S1]
• Array out of bounds: int[] numbers = {1, 2, 3}; System.out.println(numbers[8]); // ArrayIndexOutOfBoundsException. [S1]
• Logical error: int sum = x - y; when addition was intended — no exception thrown, just wrong output. [S1]

⚖️ 모순 및 업데이트 (Contradictions & updates)

소스에서 모순되는 정보는 발견되지 않음.

🛠️ 적용 사례 (Applied in summary)

현재 발견된 실제 적용 사례가 없습니다 — 세 가지 에러 유형 분류는 이후 디버깅/예외 처리 챕터의 기초 개념이다. [S1]

💻 코드 패턴 (Code patterns)

Logical error — code runs but result is wrong (Java):

int x = 10;
int y = 2;
int sum = x - y;  // mistakenly subtracts instead of adds
System.out.println("x + y = " + sum);  // "x + y = 8" (expected 12)

✅ 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 Debugging, Java Try Catch
• 참조 맥락: 에러 유형 분류(컴파일/런타임/논리) — 디버깅 챕터로 직접 이어짐.

📚 출처 (Sources)

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

📝 변경 이력 (Change history)

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