2nd/10_Wiki/Dev/Topic_Java/Java_Inheritance.md

id, title, category, status, verification_status, canonical_id, aliases, duplicate_of, source_trust_level, confidence_score, created_at, updated_at, review_reason, merge_history, tags, raw_sources, applied_in, github_commit

id	title	category	status	verification_status	canonical_id	aliases	duplicate_of	source_trust_level	confidence_score	created_at	updated_at	review_reason	merge_history	tags	raw_sources	applied_in	github_commit
java-inheritance	Java Inheritance	Programming_Language	draft	conceptual		subclass superclass extends keyword 자바 상속		B	0.9	2026-07-04	2026-07-04			java programming w3schools oop inheritance	https://www.w3schools.com/java/java_inheritance.asp

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).