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78 lines
3.4 KiB
Markdown
78 lines
3.4 KiB
Markdown
---
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id: java-abstraction
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title: "Java Abstraction"
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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: ["abstract classes", "자바 추상화"]
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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", "oop", "abstraction", "abstract-class"]
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raw_sources: ["https://www.w3schools.com/java/java_abstract.asp"]
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applied_in: []
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github_commit: ""
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---
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# [[Java Abstraction]]
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## 🎯 한 줄 통찰 (One-line insight)
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An abstract class can freely mix abstract methods (no body) and regular concrete methods (`sleep()` with a real implementation) in the same class — abstraction isn't all-or-nothing; a class can force subclasses to implement SOME behavior while providing shared behavior for the rest. [S1]
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## 🧠 핵심 개념 (Core concepts)
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- **Abstraction** — hiding implementation details, showing only essential information to the user. [S1]
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- **Two mechanisms** — abstract classes or interfaces (interfaces covered next chapter). [S1]
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- **Abstract class** — cannot be instantiated directly; must be inherited to be used. [S1]
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- **Abstract method** — declared in an abstract class, has no body; the subclass supplies the body. [S1]
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- **Mixed abstract class** — can contain BOTH abstract methods and fully-implemented regular methods. [S1]
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## 📖 세부 내용 (Details)
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- Abstract class definition: `abstract class Animal { public abstract void animalSound(); public void sleep() { System.out.println("Zzz"); } }`. [S1]
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- Cannot instantiate: `Animal myObj = new Animal(); // error`. [S1]
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- Subclass provides the body: `class Pig extends Animal { public void animalSound() { System.out.println("The pig says: wee wee"); } } ... Pig myPig = new Pig(); myPig.animalSound(); myPig.sleep();`. [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 — 보안(중요 세부사항만 노출)을 위한 설계 원칙으로 소개된다. [S1]
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## 💻 코드 패턴 (Code patterns)
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Abstract class mixing abstract and regular methods (Java):
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```java
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abstract class Animal {
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public abstract void animalSound(); // no body
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public void sleep() { // regular method
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System.out.println("Zzz");
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}
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}
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class Pig extends Animal {
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public void animalSound() {
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System.out.println("The pig says: wee wee");
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}
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}
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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 Non Access Modifiers]], [[Java Polymorphism]], [[Java Interface]]
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- **참조 맥락:** 인터페이스와 함께 추상화를 달성하는 두 방법 중 하나 — Interface 챕터로 직접 이어짐.
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## 📚 출처 (Sources)
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- [S1] W3Schools — Java Abstraction — https://www.w3schools.com/java/java_abstract.asp
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## 📝 변경 이력 (Change history)
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- 2026-07-04: Initial draft synthesized from the W3Schools "Java Abstraction" page (Astra wiki-curation, P-Reinforce v3.1 format).
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