---
id: java-while-loop
title: "Java While Loop"
category: "Programming_Language"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["while loop", "자바 while 반복문"]
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", "loops", "while"]
raw_sources: ["https://www.w3schools.com/java/java_while_loop.asp"]
applied_in: []
github_commit: ""
---

# [[Java While Loop]]

## 🎯 한 줄 통찰 (One-line insight)
A while loop's condition is checked BEFORE each iteration, so a condition that's false from the start means the loop body never runs even once — a property the source contrasts against the (not-yet-covered) do/while loop's guaranteed-first-run behavior. [S1]

## 🧠 핵심 개념 (Core concepts)
- **`while (condition) { ... }`** — repeats the block as long as the condition stays true. [S1]
- **Counter variable `i`** — conventional name meaning "index"/"iterator"; short and traditional. [S1]
- **Must update the condition variable** — forgetting `i++` causes an infinite loop. [S1]
- **Countdown pattern** — decrementing (`countdown--`) works the same way. [S1]
- **False-from-start behavior** — if the condition is false initially, the loop body never executes. [S1]

## 📖 세부 내용 (Details)
- Basic counting: `int i = 0; while (i < 5) { System.out.println(i); i++; }`. [S1]
- Countdown: `int countdown = 3; while (countdown > 0) { System.out.println(countdown); countdown--; } System.out.println("Happy New Year!!");`. [S1]
- Never runs: `int i = 10; while (i < 5) { System.out.println("This will never be printed"); i++; }`. [S1]

## ⚖️ 모순 및 업데이트 (Contradictions & updates)
소스에서 모순되는 정보는 발견되지 않음.

## 🛠️ 적용 사례 (Applied in summary)
현재 발견된 실제 적용 사례가 없습니다 — 카운트다운, 조건 기반 반복의 기본형이며 do/while과의 차이가 다음 챕터의 핵심 주제다. [S1]

## 💻 코드 패턴 (Code patterns)
Basic while loop with counter (Java):
```java
int i = 0;
while (i < 5) {
    System.out.println(i);
    i++;
}
```

## ✅ 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 Do While Loop]], [[Java While Loop Real Life]], [[Java For Loop]]
- **참조 맥락:** 조건 기반 반복의 기본형 — do/while과의 실행 시점 차이가 핵심 대비점.

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

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