---
id: java-errors
title: "Java Errors"
category: "Programming_Language"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["자바 에러 유형"]
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", "errors"]
raw_sources: ["https://www.w3schools.com/java/java_errors.asp"]
applied_in: []
github_commit: ""
---

# [[Java Errors]]

## 🎯 한 줄 통찰 (One-line insight)
Logical errors are explicitly called "hardest to find" because the program compiles AND runs without crashing — it just produces wrong results (e.g., `x - y` instead of `x + y`), meaning no error message points you to the bug; only testing against expected output reveals it. [S1]

## 🧠 핵심 개념 (Core concepts)
- **Compile-time error** — detected by the compiler, prevents the code from running (syntax/type issues). [S1]
- **Runtime error** — occurs while running, often causes crashes (e.g., division by zero, out-of-bounds access). [S1]
- **Logical error** — code runs and produces output, but the output is wrong; hardest category to detect. [S1]
- **Good habits** — meaningful variable names, reading error messages for line numbers, checking for missing semicolons/braces, watching for typos. [S1]

## 📖 세부 내용 (Details)
- Missing semicolon: `int x = 5 System.out.println(x); // error: ';' expected`. [S1]
- Undeclared variable: `System.out.println(myVar); // cannot find symbol: variable myVar`. [S1]
- Mismatched types: `int x = "Hello"; // incompatible types: String cannot be converted to int`. [S1]
- Division by zero: `int x = 10; int y = 0; int result = x / y; // ArithmeticException: / by zero`. [S1]
- Array out of bounds: `int[] numbers = {1, 2, 3}; System.out.println(numbers[8]); // ArrayIndexOutOfBoundsException`. [S1]
- Logical error: `int sum = x - y;` when addition was intended — no exception thrown, just wrong output. [S1]

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

## 🛠️ 적용 사례 (Applied in summary)
현재 발견된 실제 적용 사례가 없습니다 — 세 가지 에러 유형 분류는 이후 디버깅/예외 처리 챕터의 기초 개념이다. [S1]

## 💻 코드 패턴 (Code patterns)
Logical error — code runs but result is wrong (Java):
```java
int x = 10;
int y = 2;
int sum = x - y;  // mistakenly subtracts instead of adds
System.out.println("x + y = " + sum);  // "x + y = 8" (expected 12)
```

## ✅ 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 Debugging]], [[Java Try Catch]]
- **참조 맥락:** 에러 유형 분류(컴파일/런타임/논리) — 디버깅 챕터로 직접 이어짐.

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

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