---
id: java-arrays
title: "Java Arrays"
category: "Programming_Language"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["자바 배열"]
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", "arrays"]
raw_sources: ["https://www.w3schools.com/java/java_arrays.asp"]
applied_in: []
github_commit: ""
---

# [[Java Arrays]]

## 🎯 한 줄 통찰 (One-line insight)
`new TYPE[size]` and the `{...}` literal shortcut cannot be combined (`new String[4] {"Volvo",...}` is illegal) — you must choose one of two modes: reserve empty slots to fill later, OR declare-and-populate at once, never both. [S1]

## 🧠 핵심 개념 (Core concepts)
- **Declaration** — `String[] cars;` declares an array variable of a type with `[]`. [S1]
- **Literal initialization** — `String[] cars = {"Volvo", "BMW", "Ford", "Mazda"};`. [S1]
- **Zero-based indexing** — `cars[0]` is the first element. [S1]
- **Element mutation** — `cars[0] = "Opel";` overwrites by index. [S1]
- **`.length`** — property (not a method call) returning element count. [S1]
- **`new` keyword** — `new String[4]` creates an empty fixed-size array to fill later; mutually exclusive with the literal shortcut in the same declaration. [S1]

## 🧩 추출된 패턴 (Extracted patterns)
- **new + literal is illegal together** — `new String[4] {"Volvo", "BMW", "Ford", "Mazda"}` doesn't compile; you either specify a size (`new String[4]`) OR values (`new String[] {...}` / the bare `{...}` shortcut), never both in one `new` expression. [S1]

## 📖 세부 내용 (Details)
- Access: `String[] cars = {"Volvo", "BMW", "Ford", "Mazda"}; System.out.println(cars[0]); // Volvo`. [S1]
- Mutation: `cars[0] = "Opel"; // Now outputs Opel instead of Volvo`. [S1]
- Length: `System.out.println(cars.length); // 4`. [S1]
- Empty-then-fill with new: `String[] cars = new String[4]; cars[0] = "Volvo"; ...`. [S1]
- Equivalent forms: `String[] cars = new String[] {"Volvo", "BMW", "Ford", "Mazda"};` vs. the shortcut `String[] cars = {"Volvo", "BMW", "Ford", "Mazda"};` (most common). [S1]

## ⚖️ 모순 및 업데이트 (Contradictions & updates)
- **new와 리터럴의 배타성**: new String[4]와 리터럴 초기화를 동시에 쓸 수 없다는 점이 소스에서 명시적으로 강조됨. [S1]

## 🛠️ 적용 사례 (Applied in summary)
현재 발견된 실제 적용 사례가 없습니다 — 여러 값을 하나의 변수로 관리하는 기본 자료구조로, 이후 루프/다차원 배열의 기반이 된다. [S1]

## 💻 코드 패턴 (Code patterns)
Array declaration and index access (Java):
```java
String[] cars = {"Volvo", "BMW", "Ford", "Mazda"};
System.out.println(cars[0]);  // Volvo
System.out.println(cars.length);  // 4
```

## ✅ 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 For Each Loop]], [[Java Arrays Loop]], [[Java Arrays Multi]]
- **참조 맥락:** 여러 값을 하나의 변수로 관리하는 기본 자료구조 — Loop/Multi 챕터로 확장.

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

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