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Antigravity Agent e9cbf23ab5 docs(10_Wiki): Dev 폴더 누락분 반영 — Topic_Programming으로 통합

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  JavaScript/PHP/Python/SQL/W3CSS, 1201개)는 전부 Topic_Programming 하위로 이동.
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- Topic_Programming 최종 문서 수: 2784 → 3985.

2026-07-05 00:39:13 +09:00

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title

Java Inheritance

🎯 한 줄 통찰 (One-line insight)

The choice between protected and private on a parent attribute directly determines whether inheritance "works" for that field — the source deliberately uses protected on Vehicle's brand and notes that private would have blocked Car from accessing it at all. [S1]

🧠 핵심 개념 (Core concepts)

Subclass (child) — the class that inherits from another. [S1]
Superclass (parent) — the class being inherited from. [S1]
extends — keyword used to inherit from a class. [S1]
protected — required (not private) if a subclass needs to access a parent attribute directly. [S1]
final on a class — prevents any class from extending it; attempting to do so is a compile error. [S1]
Motivation — code reusability: inherit attributes/methods of an existing class into a new one. [S1]

📖 세부 내용 (Details)

Basic inheritance: class Vehicle { protected String brand = "Ford"; public void honk() { System.out.println("Tuut, tuut!"); } } class Car extends Vehicle { private String modelName = "Mustang"; ... } ... myCar.honk(); myCar.brand + " " + myCar.modelName;. [S1]
Final class blocks inheritance: final class Vehicle { ... } class Car extends Vehicle { ... } // error: cannot inherit from final Vehicle. [S1]

⚖️ 모순 및 업데이트 (Contradictions & updates)

protected 필수성: brand가 private이었다면 Car 클래스가 접근할 수 없었을 것이라는 점이 명시적으로 강조됨. [S1]

🛠️ 적용 사례 (Applied in summary)

현재 발견된 실제 적용 사례가 없습니다 — Vehicle→Car 상속 구조는 다형성(Polymorphism) 챕터의 직접적 전제가 된다. [S1]

💻 코드 패턴 (Code patterns)

Subclass inheriting a protected attribute and a method (Java):

class Vehicle {
    protected String brand = "Ford";
    public void honk() {
        System.out.println("Tuut, tuut!");
    }
}
class Car extends Vehicle {
    private String modelName = "Mustang";
    public static void main(String[] args) {
        Car myCar = new Car();
        myCar.honk();
        System.out.println(myCar.brand + " " + myCar.modelName);
    }
}

✅ 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 Modifiers, Java Polymorphism, Java Super Keyword, Java Abstraction
참조 맥락: 클래스 간 속성/메서드 재사용 — 다형성/super 키워드 챕터로 직접 이어짐.

📚 출처 (Sources)

[S1] W3Schools — Java Inheritance (Subclass and Superclass) — https://www.w3schools.com/java/java_inheritance.asp

📝 변경 이력 (Change history)

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

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