docs(10_Wiki): Topic_Business/General/Graphic/Programming을 Topics/ 하위로 이동

최상위 10_Wiki/Topic_*였던 4개 카테고리 폴더를 10_Wiki/Topics/Topic_* 로 재배치. 콘텐츠 변경 없음(순수 폴더 이동) — Topics/ 하위 나머지 폴더는 이미 지난 커밋에서 전부 정리된 상태(잔존 항목은 에이전트 운영 상태 및 사용자가 보존을 요청한 업데이트0615/무제 3.canvas 뿐).
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+---
+id: java-abstraction
+title: "Java Abstraction"
+category: "Programming_Language"
+status: "draft"
+verification_status: "conceptual"
+canonical_id: ""
+aliases: ["abstract classes", "자바 추상화"]
+duplicate_of: ""
+source_trust_level: "B"
+confidence_score: 0.9
+created_at: 2026-07-04
+updated_at: 2026-07-04
+review_reason: ""
+merge_history: []
+tags: ["java", "programming", "w3schools", "oop", "abstraction", "abstract-class"]
+raw_sources: ["https://www.w3schools.com/java/java_abstract.asp"]
+applied_in: []
+github_commit: ""
+---
+
+# [[Java Abstraction]]
+
+## 🎯 한 줄 통찰 (One-line insight)
+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]
+
+## 🧠 핵심 개념 (Core concepts)
+- **Abstraction** — hiding implementation details, showing only essential information to the user. [S1]
+- **Two mechanisms** — abstract classes or interfaces (interfaces covered next chapter). [S1]
+- **Abstract class** — cannot be instantiated directly; must be inherited to be used. [S1]
+- **Abstract method** — declared in an abstract class, has no body; the subclass supplies the body. [S1]
+- **Mixed abstract class** — can contain BOTH abstract methods and fully-implemented regular methods. [S1]
+
+## 📖 세부 내용 (Details)
+- Abstract class definition: `abstract class Animal { public abstract void animalSound(); public void sleep() { System.out.println("Zzz"); } }`. [S1]
+- Cannot instantiate: `Animal myObj = new Animal(); // error`. [S1]
+- 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]
+
+## ⚖️ 모순 및 업데이트 (Contradictions & updates)
+소스에서 모순되는 정보는 발견되지 않음.
+
+## 🛠️ 적용 사례 (Applied in summary)
+현재 발견된 실제 적용 사례가 없습니다 — 보안(중요 세부사항만 노출)을 위한 설계 원칙으로 소개된다. [S1]
+
+## 💻 코드 패턴 (Code patterns)
+Abstract class mixing abstract and regular methods (Java):
+```java
+abstract class Animal {
+    public abstract void animalSound(); // no body
+    public void sleep() {               // regular method
+        System.out.println("Zzz");
+    }
+}
+class Pig extends Animal {
+    public void animalSound() {
+        System.out.println("The pig says: wee wee");
+    }
+}
+```
+
+## ✅ 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 Non Access Modifiers]], [[Java Polymorphism]], [[Java Interface]]
+- **참조 맥락:** 인터페이스와 함께 추상화를 달성하는 두 방법 중 하나 — Interface 챕터로 직접 이어짐.
+
+## 📚 출처 (Sources)
+- [S1] W3Schools — Java Abstraction — https://www.w3schools.com/java/java_abstract.asp
+
+## 📝 변경 이력 (Change history)
+- 2026-07-04: Initial draft synthesized from the W3Schools "Java Abstraction" page (Astra wiki-curation, P-Reinforce v3.1 format).