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78 lines
3.3 KiB
Markdown
78 lines
3.3 KiB
Markdown
---
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id: java-variables
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title: "Java Variables"
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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: ["자바 변수"]
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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", "variables"]
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raw_sources: ["https://www.w3schools.com/java/java_variables.asp"]
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applied_in: []
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github_commit: ""
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---
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# [[Java Variables]]
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## 🎯 한 줄 통찰 (One-line insight)
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Unlike Python, Java is statically typed — every variable declaration must state a type (`type variableName = value;`), and that type cannot silently change later the way Python's dynamic typing allows. [S1]
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## 🧠 핵심 개념 (Core concepts)
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- **Basic types** — `String` (text, double-quoted), `int` (whole numbers), `float` (decimals), `char` (single character, single-quoted), `boolean` (true/false). [S1]
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- **Declaration syntax** — `type variableName = value;`. [S1]
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- **Declare-then-assign** — `int myNum; myNum = 15;` is also valid, splitting declaration and assignment. [S1]
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- **Reassignment overwrites** — assigning a new value replaces the old one. [S1]
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- **`final` keyword** — makes a variable unchangeable/read-only; reassigning raises a compile error. [S1]
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## 🧩 추출된 패턴 (Extracted patterns)
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- **Static typing is the core Java/Python divergence** — every Java variable's type is fixed at declaration and enforced by the compiler, unlike Python where `x = 4; x = "Sally"` is legal. [S1]
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## 📖 세부 내용 (Details)
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- String declaration: `String name = "John"; System.out.println(name);`. [S1]
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- Int declaration: `int myNum = 15;`. [S1]
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- Separate declare/assign: `int myNum; myNum = 15;`. [S1]
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- Reassignment: `int myNum = 15; myNum = 20;`. [S1]
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- final (immutable): `final int myNum = 15; myNum = 20; // error`. [S1]
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- All basic types together: `int myNum = 5; float myFloatNum = 5.99f; char myLetter = 'D'; boolean myBool = true; String myText = "Hello";`. [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 — 이후 Data Types 챕터에서 각 타입이 상세히 다뤄진다. [S1]
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## 💻 코드 패턴 (Code patterns)
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Five basic types declared (Java):
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```java
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int myNum = 5;
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float myFloatNum = 5.99f;
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char myLetter = 'D';
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boolean myBool = true;
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String myText = "Hello";
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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 Constants Final]], [[Python Variables]]
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- **참조 맥락:** 정적 타이핑이라는 Java의 핵심 특성 — Python의 동적 타이핑과 대비.
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## 📚 출처 (Sources)
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- [S1] W3Schools — Java Variables — https://www.w3schools.com/java/java_variables.asp
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## 📝 변경 이력 (Change history)
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- 2026-07-04: Initial draft synthesized from the W3Schools "Java Variables" page (Astra wiki-curation, P-Reinforce v3.1 format).
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