2nd/10_Wiki/Dev/Topic_Java/Java_Abstraction.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-abstraction	Java Abstraction	Programming_Language	draft	conceptual		abstract classes 자바 추상화		B	0.9	2026-07-04	2026-07-04			java programming w3schools oop abstraction abstract-class	https://www.w3schools.com/java/java_abstract.asp

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):

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).