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77 lines
3.5 KiB
Markdown
77 lines
3.5 KiB
Markdown
---
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id: java-date
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title: "Java Date"
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category: "Programming_Language"
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status: "draft"
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verification_status: "conceptual"
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canonical_id: ""
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aliases: ["java.time package", "자바 날짜와 시간"]
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duplicate_of: ""
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source_trust_level: "B"
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confidence_score: 0.9
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created_at: 2026-07-04
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updated_at: 2026-07-04
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review_reason: ""
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merge_history: []
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tags: ["java", "programming", "w3schools", "date", "time", "java.time"]
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raw_sources: ["https://www.w3schools.com/java/java_date.asp"]
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applied_in: []
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github_commit: ""
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---
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# [[Java Date]]
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## 🎯 한 줄 통찰 (One-line insight)
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Java has NO built-in Date class of its own — dates/times require importing the `java.time` package (LocalDate/LocalTime/LocalDateTime/DateTimeFormatter), a design choice the tutorial states upfront rather than assuming a language-level date type. [S1]
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## 🧠 핵심 개념 (Core concepts)
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- **`java.time` package** — required import for all date/time functionality. [S1]
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- **`LocalDate`** — represents a date only (`yyyy-MM-dd`). [S1]
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- **`LocalTime`** — represents a time only (`HH-mm-ss-ns`). [S1]
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- **`LocalDateTime`** — combines both date and time. [S1]
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- **`DateTimeFormatter`** — formats/parses date-time objects via `ofPattern(...)`. [S1]
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- **`.now()`** — static method on LocalDate/LocalTime/LocalDateTime returning the current value. [S1]
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- **The "T" separator** — LocalDateTime's default string form uses "T" to separate date from time; removable via formatting. [S1]
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## 📖 세부 내용 (Details)
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- Current date: `LocalDate myObj = LocalDate.now(); // 2026-07-04`. [S1]
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- Current time: `LocalTime myObj = LocalTime.now(); // 9:58:29.366162`. [S1]
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- Current date+time: `LocalDateTime myObj = LocalDateTime.now(); // 2026-07-04T09:58:29.366392`. [S1]
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- Custom formatting: `DateTimeFormatter myFormatObj = DateTimeFormatter.ofPattern("dd-MM-yyyy HH:mm:ss"); String formattedDate = myDateObj.format(myFormatObj); // 04-07-2026 09:58:29`. [S1]
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- Pattern examples: `yyyy-MM-dd` → "1988-09-29"; `dd/MM/yyyy` → "29/09/1988"; `dd-MMM-yyyy` → "29-Sep-1988"; `E, MMM dd yyyy` → "Thu, Sep 29 1988". [S1]
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## ⚖️ 모순 및 업데이트 (Contradictions & updates)
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소스에서 모순되는 정보는 발견되지 않음.
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## 🛠️ 적용 사례 (Applied in summary)
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현재 발견된 실제 적용 사례가 없습니다 — 로그 타임스탬프, 사용자 표시용 날짜 포맷 변환의 표준 패턴이다. [S1]
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## 💻 코드 패턴 (Code patterns)
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Custom date-time formatting (Java):
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```java
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import java.time.LocalDateTime;
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import java.time.format.DateTimeFormatter;
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LocalDateTime myDateObj = LocalDateTime.now();
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DateTimeFormatter myFormatObj = DateTimeFormatter.ofPattern("dd-MM-yyyy HH:mm:ss");
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String formattedDate = myDateObj.format(myFormatObj);
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```
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## ✅ 검증 상태 및 신뢰도
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- **상태:** draft
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- **검증 단계:** conceptual
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- **출처 신뢰도:** B (W3Schools — widely used educational reference, not a primary standards body)
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- **신뢰 점수:** 0.90
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- **중복 검사 결과:** 신규 생성 (New discovery)
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## 🔗 지식 그래프 (Knowledge Graph)
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- **상위/루트:** [[Java Tutorial]]
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- **관련 개념:** [[Java Packages]], [[Java User Input]], [[Java Errors]]
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- **참조 맥락:** java.time 패키지를 통한 날짜/시간 처리 — 에러/예외 챕터로 이어짐.
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## 📚 출처 (Sources)
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- [S1] W3Schools — Java Date and Time — https://www.w3schools.com/java/java_date.asp
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## 📝 변경 이력 (Change history)
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- 2026-07-04: Initial draft synthesized from the W3Schools "Java Date and Time" page (Astra wiki-curation, P-Reinforce v3.1 format).
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