---
id: java-try-catch
title: "Java Try Catch"
category: "Programming_Language"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["exception handling", "자바 예외 처리"]
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", "exceptions", "try-catch"]
raw_sources: ["https://www.w3schools.com/java/java_try_catch.asp"]
applied_in: []
github_commit: ""
---

# [[Java Try Catch]]

## 🎯 한 줄 통찰 (One-line insight)
`finally` runs regardless of outcome — even after a caught exception — making it the guaranteed place for cleanup code that must execute whether the try block succeeded or the catch block fired, distinct from code placed after the whole try/catch structure. [S1]

## 🧠 핵심 개념 (Core concepts)
- **Exception** — Java's technical term for the error object thrown when something goes wrong at runtime. [S1]
- **`try`** — defines a block of code to test for errors during execution. [S1]
- **`catch(Exception e)`** — defines a block that runs if an error occurs in the try block. [S1]
- **`finally`** — runs after try/catch regardless of the result. [S1]
- **`throw`** — creates and raises a custom exception, paired with an exception type (e.g. `ArithmeticException`). [S1]
- **Common exception types** — `ArithmeticException`, `ArrayIndexOutOfBoundsException`, `ClassNotFoundException`, `FileNotFoundException`, `InputMismatchException`, `IOException`, `NullPointerException`, `NumberFormatException`, `StringIndexOutOfBoundsException`. [S1]

## 📖 세부 내용 (Details)
- Uncaught exception: `int[] myNumbers = {1, 2, 3}; System.out.println(myNumbers[10]); // ArrayIndexOutOfBoundsException: 10`. [S1]
- Caught with try/catch: `try { System.out.println(myNumbers[10]); } catch (Exception e) { System.out.println("Something went wrong."); }`. [S1]
- With finally: `try {...} catch (Exception e) {...} finally { System.out.println("The 'try catch' is finished."); }` — finally always runs. [S1]
- Custom throw: `static void checkAge(int age) { if (age < 18) { throw new ArithmeticException("Access denied - You must be at least 18 years old."); } else { System.out.println("Access granted - You are old enough!"); } }`. [S1]

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

## 🛠️ 적용 사례 (Applied in summary)
현재 발견된 실제 적용 사례가 없습니다 — 나이 체크에 throw로 커스텀 예외를 발생시키는 패턴이 실전 검증 로직의 대표 사례다. [S1]

## 💻 코드 패턴 (Code patterns)
Try/catch/finally with custom throw (Java):
```java
static void checkAge(int age) {
    if (age < 18) {
        throw new ArithmeticException("Access denied - You must be at least 18 years old.");
    } else {
        System.out.println("Access granted - You are old enough!");
    }
}
```

## ✅ 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 Exceptions Multiple]], [[Java Try Catch Resources]]
- **참조 맥락:** 예외 처리의 기초 문법 — 다중 예외 처리(Multiple Exceptions) 챕터로 이어짐.

## 📚 출처 (Sources)
- [S1] W3Schools — Java Exceptions - Try...Catch — https://www.w3schools.com/java/java_try_catch.asp

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