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76 lines
3.5 KiB
Markdown
76 lines
3.5 KiB
Markdown
---
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id: java-numbers
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title: "Java Numbers"
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category: "Programming_Language"
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status: "draft"
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verification_status: "conceptual"
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canonical_id: ""
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aliases: ["byte short int long float double", "자바 숫자 타입"]
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duplicate_of: ""
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source_trust_level: "B"
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confidence_score: 0.9
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created_at: 2026-07-04
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updated_at: 2026-07-04
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review_reason: ""
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merge_history: []
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tags: ["java", "programming", "w3schools", "numbers", "int", "double"]
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raw_sources: ["https://www.w3schools.com/java/java_data_types_numbers.asp"]
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applied_in: []
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github_commit: ""
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---
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# [[Java Numbers]]
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## 🎯 한 줄 통찰 (One-line insight)
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`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]
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## 🧠 핵심 개념 (Core concepts)
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- **Integer types** — `byte`, `short`, `int` (preferred default for whole numbers), `long` (for values too large for int, requires `L` suffix). [S1]
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- **Floating point types** — `float` (requires `f` suffix, 6-7 decimal digit precision), `double` (15-16 digit precision, preferred for most calculations). [S1]
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- **Scientific notation** — `float f1 = 35e3f; double d1 = 12E4d;` uses `e`/`E` for powers of 10. [S1]
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## 🧩 추출된 패턴 (Extracted patterns)
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- **Literal suffix requirement scales with type size** — `L` 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]
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- **double as the safe default for decimals** — the tutorial explicitly recommends double over float for most calculations due to its much higher precision. [S1]
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## 📖 세부 내용 (Details)
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- byte: `byte myNum = 100;` (range -128 to 127). [S1]
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- short: `short myNum = 5000;` (range -32768 to 32767). [S1]
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- int: `int myNum = 100000;` (preferred default). [S1]
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- long: `long myNum = 15000000000L;` (note the `L` suffix). [S1]
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- float: `float myNum = 5.75f;`. [S1]
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- double: `double myNum = 19.99d;`. [S1]
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- Scientific notation: `float f1 = 35e3f; double d1 = 12E4d;`. [S1]
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## ⚖️ 모순 및 업데이트 (Contradictions & updates)
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소스에서 모순되는 정보는 발견되지 않음.
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## 🛠️ 적용 사례 (Applied in summary)
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현재 발견된 실제 적용 사례가 없습니다 — Type Casting 챕터에서 이 숫자 타입들 간 자동/수동 변환이 다뤄진다. [S1]
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## 💻 코드 패턴 (Code patterns)
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Long and float literal suffixes (Java):
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```java
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long myNum = 15000000000L;
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float myFloat = 5.75f;
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double myDouble = 19.99d; // d is optional (double is the default)
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```
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## ✅ 검증 상태 및 신뢰도
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- **상태:** draft
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- **검증 단계:** conceptual
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- **출처 신뢰도:** B (W3Schools — widely used educational reference, not a primary standards body)
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- **신뢰 점수:** 0.90
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- **중복 검사 결과:** 신규 생성 (New discovery)
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## 🔗 지식 그래프 (Knowledge Graph)
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- **상위/루트:** [[Java Tutorial]]
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- **관련 개념:** [[Java Data Types]], [[Java Type Casting]], [[Java Math]]
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- **참조 맥락:** 6개 숫자 타입의 상세 — 리터럴 접미사(L/f/d) 규칙이 핵심.
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## 📚 출처 (Sources)
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- [S1] W3Schools — Java Numbers — https://www.w3schools.com/java/java_data_types_numbers.asp
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## 📝 변경 이력 (Change history)
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- 2026-07-04: Initial draft synthesized from the W3Schools "Java Numbers" page (Astra wiki-curation, P-Reinforce v3.1 format).
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