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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
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-numbers Java Numbers Programming_Language draft conceptual
byte short int long float double
자바 숫자 타입
B 0.9 2026-07-04 2026-07-04
java
programming
w3schools
numbers
int
double
https://www.w3schools.com/java/java_data_types_numbers.asp

Java Numbers

🎯 한 줄 통찰 (One-line insight)

long values need a trailing L and float values need a trailing f (double needs d, but it's optional since double is the default) — omitting these suffixes on large/decimal literals causes compile errors or silent precision loss. [S1]

🧠 핵심 개념 (Core concepts)

  • Integer typesbyte, short, int (preferred default for whole numbers), long (for values too large for int, requires L suffix). [S1]
  • Floating point typesfloat (requires f suffix, 6-7 decimal digit precision), double (15-16 digit precision, preferred for most calculations). [S1]
  • Scientific notationfloat f1 = 35e3f; double d1 = 12E4d; uses e/E for powers of 10. [S1]

🧩 추출된 패턴 (Extracted patterns)

  • Literal suffix requirement scales with type sizeL for long, f for float, d for double (optional) — the suffix tells the compiler which literal type to use, since Java's default numeric literal types are int and double. [S1]
  • double as the safe default for decimals — the tutorial explicitly recommends double over float for most calculations due to its much higher precision. [S1]

📖 세부 내용 (Details)

  • byte: byte myNum = 100; (range -128 to 127). [S1]
  • short: short myNum = 5000; (range -32768 to 32767). [S1]
  • int: int myNum = 100000; (preferred default). [S1]
  • long: long myNum = 15000000000L; (note the L suffix). [S1]
  • float: float myNum = 5.75f;. [S1]
  • double: double myNum = 19.99d;. [S1]
  • Scientific notation: float f1 = 35e3f; double d1 = 12E4d;. [S1]

⚖️ 모순 및 업데이트 (Contradictions & updates)

소스에서 모순되는 정보는 발견되지 않음.

🛠️ 적용 사례 (Applied in summary)

현재 발견된 실제 적용 사례가 없습니다 — Type Casting 챕터에서 이 숫자 타입들 간 자동/수동 변환이 다뤄진다. [S1]

💻 코드 패턴 (Code patterns)

Long and float literal suffixes (Java):

long myNum = 15000000000L;
float myFloat = 5.75f;
double myDouble = 19.99d;  // d is optional (double is the default)

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)

📚 출처 (Sources)

📝 변경 이력 (Change history)

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