---
id: java-enums
title: "Java Enums"
category: "Programming_Language"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["enum keyword", "자바 열거형"]
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", "oop", "enums"]
raw_sources: ["https://www.w3schools.com/java/java_enums.asp"]
applied_in: []
github_commit: ""
---

# [[Java Enums]]

## 🎯 한 줄 통찰 (One-line insight)
Enums can have attributes and methods just like classes, but with one key restriction that defines their whole purpose — enum constants are always `public`, `static`, and `final`, meaning you can never create an object from an enum or override its values, only select from a fixed listed set. [S1]

## 🧠 핵심 개념 (Core concepts)
- **`enum`** — a special class representing a group of unchangeable constants. [S1]
- **Naming convention** — constants written in uppercase, comma-separated. [S1]
- **Dot-syntax access** — `Level myVar = Level.MEDIUM;`. [S1]
- **Enum inside a class** — enums can be nested inside a regular class. [S1]
- **Switch compatibility** — enums work naturally as switch expressions, with case labels matching constant names (no dot prefix in case labels). [S1]
- **`values()`** — built-in method returning an array of all enum constants, useful for looping. [S1]
- **Constraints vs. classes** — cannot instantiate objects from an enum; cannot extend other classes (but CAN implement interfaces). [S1]

## 📖 세부 내용 (Details)
- Basic enum: `enum Level { LOW, MEDIUM, HIGH } ... Level myVar = Level.MEDIUM;`. [S1]
- Switch on enum: `switch(myVar) { case LOW: ...; case MEDIUM: System.out.println("Medium level"); break; case HIGH: ...; }`. [S1]
- Loop via values(): `for (Level myVar : Level.values()) { System.out.println(myVar); } // LOW MEDIUM HIGH`. [S1]

## ⚖️ 모순 및 업데이트 (Contradictions & updates)
- **불변성 제약**: enum 상수는 public, static, final이므로 객체 생성이 불가하고 값 재정의도 불가하다는 점이 명확히 구분됨. [S1]

## 🛠️ 적용 사례 (Applied in summary)
현재 발견된 실제 적용 사례가 없습니다 — 요일, 색상, 카드 덱처럼 값이 절대 바뀌지 않는 고정 집합을 표현할 때 사용된다. [S1]

## 💻 코드 패턴 (Code patterns)
Enum used in a switch statement (Java):
```java
enum Level { LOW, MEDIUM, HIGH }
Level myVar = Level.MEDIUM;
switch (myVar) {
    case LOW: System.out.println("Low level"); break;
    case MEDIUM: System.out.println("Medium level"); break;
    case HIGH: System.out.println("High level"); break;
}
```

## ✅ 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 Switch]], [[Java Enum Constructor]], [[Java Interface]]
- **참조 맥락:** 고정 상수 집합 표현 — 생성자를 갖는 enum(Enum Constructor)으로 확장.

## 📚 출처 (Sources)
- [S1] W3Schools — Java Enums — https://www.w3schools.com/java/java_enums.asp

## 📝 변경 이력 (Change history)
- 2026-07-04: Initial draft synthesized from the W3Schools "Java Enums" page (Astra wiki-curation, P-Reinforce v3.1 format).