docs(10_Wiki): 위키 구조 정리 — 언어 튜토리얼 카테고리 폴더 제거 + 신규 자산 동기화

Topic_CSS/Topic_HTML/Topic_JavaScript/Topic_Prompt/Topic_Comfyui 등 기존 카테고리 폴더를 정리하고, Topic_Graphic/Dev 등 신규 산출물과 Topics 내부 세션/메모리 기록을 동기화.
2026-07-05 00:10:59 +09:00
parent a397bc4720
commit 1cfd3bbb56
1495 changed files with 68534 additions and 27 deletions
@@ -0,0 +1,70 @@
+---
+id: java-wrapper-classes
+title: "Java Wrapper Classes"
+category: "Programming_Language"
+status: "draft"
+verification_status: "conceptual"
+canonical_id: ""
+aliases: ["자바 래퍼 클래스"]
+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", "wrapper-classes"]
+raw_sources: ["https://www.w3schools.com/java/java_wrapper_classes.asp"]
+applied_in: []
+github_commit: ""
+---
+
+# [[Java Wrapper Classes]]
+
+## 🎯 한 줄 통찰 (One-line insight)
+Wrapper classes exist specifically to solve a structural problem, not for convenience — Collections like ArrayList can ONLY store objects, so `ArrayList<int>` is flatly invalid Java, forcing every primitive that needs to go into a collection to first become its object wrapper (`Integer`, `Double`, etc.). [S1]
+
+## 🧠 핵심 개념 (Core concepts)
+- **Wrapper class** — lets a primitive type be used as an object. [S1]
+- **Full mapping** — byte→Byte, short→Short, int→Integer, long→Long, float→Float, double→Double, boolean→Boolean, char→Character. [S1]
+- **Required for Collections** — `ArrayList<int>` is invalid; `ArrayList<Integer>` is required. [S1]
+- **Value-extraction methods** — `intValue()`, `doubleValue()`, `charValue()`, `booleanValue()`, etc. — read the primitive value back out of the wrapper. [S1]
+- **`toString()`** — converts a wrapper object to a String, enabling String methods like `.length()`. [S1]
+
+## 📖 세부 내용 (Details)
+- Invalid vs. valid: `ArrayList<int> myNumbers = new ArrayList<int>(); // Invalid` vs. `ArrayList<Integer> myNumbers = new ArrayList<Integer>(); // Valid`. [S1]
+- Creating wrapper objects: `Integer myInt = 5; Double myDouble = 5.99; Character myChar = 'A';`. [S1]
+- Extracting values: `myInt.intValue(); myDouble.doubleValue(); myChar.charValue();`. [S1]
+- toString + String method chaining: `Integer myInt = 100; String myString = myInt.toString(); System.out.println(myString.length());`. [S1]
+
+## ⚖️ 모순 및 업데이트 (Contradictions & updates)
+소스에서 모순되는 정보는 발견되지 않음.
+
+## 🛠️ 적용 사례 (Applied in summary)
+현재 발견된 실제 적용 사례가 없습니다 — Integer를 String으로 변환 후 length()를 호출하는 패턴이 래퍼 클래스와 String 메서드 결합의 실전 사례다. [S1]
+
+## 💻 코드 패턴 (Code patterns)
+Converting a wrapper object to String via toString() (Java):
+```java
+Integer myInt = 100;
+String myString = myInt.toString();
+System.out.println(myString.length());
+```
+
+## ✅ 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 ArrayList]], [[Java Data Types]], [[Java Generics]]
+- **참조 맥락:** 원시 타입을 컬렉션에 저장하기 위한 필수 도구 — 제네릭(Generics) 챕터로 이어짐.
+
+## 📚 출처 (Sources)
+- [S1] W3Schools — Java Wrapper Classes — https://www.w3schools.com/java/java_wrapper_classes.asp
+
+## 📝 변경 이력 (Change history)
+- 2026-07-04: Initial draft synthesized from the W3Schools "Java Wrapper Classes" page (Astra wiki-curation, P-Reinforce v3.1 format).