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.
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+---
+id: java-lambda
+title: "Java Lambda"
+category: "Programming_Language"
+status: "draft"
+verification_status: "conceptual"
+canonical_id: ""
+aliases: ["lambda expressions", "자바 람다"]
+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", "lambda", "functional-interface"]
+raw_sources: ["https://www.w3schools.com/java/java_lambda.asp"]
+applied_in: []
+github_commit: ""
+---
+
+# [[Java Lambda]]
+
+## 🎯 한 줄 통찰 (One-line insight)
+A lambda can only replace an anonymous class when the target interface is "functional" (exactly ONE abstract method) — the tutorial's own rule of thumb draws the line precisely there: lambda for short single-method interfaces, anonymous class when you need multiple methods, extra fields, or to extend a class. [S1]
+
+## 🧠 핵심 개념 (Core concepts)
+- **Lambda expression** (Java 8+) — a short, nameless block of code taking parameters and returning a value. [S1]
+- **Syntax** — `parameter -> expression`; multiple parameters need parentheses; complex bodies need `{ }` + explicit `return`. [S1]
+- **Functional interface requirement** — a lambda's target type must be an interface with EXACTLY one abstract method. [S1]
+- **Common use** — passed as arguments to methods like `ArrayList.forEach()`. [S1]
+- **Built-in functional interfaces** — e.g. `Consumer<T>` from `java.util.function`. [S1]
+- **Custom functional interfaces** — user-defined single-method interfaces work as lambda targets too. [S1]
+- **Lambda vs. anonymous class rule of thumb** — lambda for short single-method interfaces; anonymous class for multiple methods/fields/extending a class. [S1]
+
+## 📖 세부 내용 (Details)
+- forEach with lambda: `numbers.forEach((n) -> { System.out.println(n); });`. [S1]
+- Lambda stored in a variable (Consumer): `Consumer<Integer> method = (n) -> { System.out.println(n); }; numbers.forEach(method);`. [S1]
+- Lambda as method parameter (custom functional interface): `interface StringFunction { String run(String str); } ... StringFunction exclaim = (s) -> s + "!"; printFormatted("Hello", exclaim);`. [S1]
+- Same task via anonymous class vs. lambda: `Greeting g = new Greeting() { public void sayHello() {...} };` vs. `Greeting g = () -> System.out.println("Hello from lambda");`. [S1]
+
+## ⚖️ 모순 및 업데이트 (Contradictions & updates)
+- **람다 사용의 전제 조건**: 대상 인터페이스가 반드시 함수형 인터페이스(추상 메서드 1개)여야 익명 클래스를 람다로 대체할 수 있다는 점이 규칙으로 명시됨. [S1]
+
+## 🛠️ 적용 사례 (Applied in summary)
+현재 발견된 실제 적용 사례가 없습니다 — ArrayList.forEach()에 람다를 전달하는 패턴이 가장 흔한 실전 활용이다. [S1]
+
+## 💻 코드 패턴 (Code patterns)
+Lambda passed to forEach() (Java):
+```java
+ArrayList<Integer> numbers = new ArrayList<Integer>();
+numbers.add(5); numbers.add(9); numbers.add(8); numbers.add(1);
+numbers.forEach((n) -> { System.out.println(n); });
+```
+
+## ✅ 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 Anonymous]], [[Java Interface]], [[Java Threads]], [[Java Advanced Sorting]]
+- **참조 맥락:** 익명 클래스의 축약형 — 고급 정렬(Comparator 람다) 챕터로 직접 이어짐.
+
+## 📚 출처 (Sources)
+- [S1] W3Schools — Java Lambda Expressions — https://www.w3schools.com/java/java_lambda.asp
+
+## 📝 변경 이력 (Change history)
+- 2026-07-04: Initial draft synthesized from the W3Schools "Java Lambda Expressions" page (Astra wiki-curation, P-Reinforce v3.1 format).