---
id: java-date
title: "Java Date"
category: "Programming_Language"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["java.time package", "자바 날짜와 시간"]
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", "date", "time", "java.time"]
raw_sources: ["https://www.w3schools.com/java/java_date.asp"]
applied_in: []
github_commit: ""
---

# [[Java Date]]

## 🎯 한 줄 통찰 (One-line insight)
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]

## 🧠 핵심 개념 (Core concepts)
- **`java.time` package** — required import for all date/time functionality. [S1]
- **`LocalDate`** — represents a date only (`yyyy-MM-dd`). [S1]
- **`LocalTime`** — represents a time only (`HH-mm-ss-ns`). [S1]
- **`LocalDateTime`** — combines both date and time. [S1]
- **`DateTimeFormatter`** — formats/parses date-time objects via `ofPattern(...)`. [S1]
- **`.now()`** — static method on LocalDate/LocalTime/LocalDateTime returning the current value. [S1]
- **The "T" separator** — LocalDateTime's default string form uses "T" to separate date from time; removable via formatting. [S1]

## 📖 세부 내용 (Details)
- Current date: `LocalDate myObj = LocalDate.now(); // 2026-07-04`. [S1]
- Current time: `LocalTime myObj = LocalTime.now(); // 9:58:29.366162`. [S1]
- Current date+time: `LocalDateTime myObj = LocalDateTime.now(); // 2026-07-04T09:58:29.366392`. [S1]
- Custom formatting: `DateTimeFormatter myFormatObj = DateTimeFormatter.ofPattern("dd-MM-yyyy HH:mm:ss"); String formattedDate = myDateObj.format(myFormatObj); // 04-07-2026 09:58:29`. [S1]
- 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]

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

## 🛠️ 적용 사례 (Applied in summary)
현재 발견된 실제 적용 사례가 없습니다 — 로그 타임스탬프, 사용자 표시용 날짜 포맷 변환의 표준 패턴이다. [S1]

## 💻 코드 패턴 (Code patterns)
Custom date-time formatting (Java):
```java
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;

LocalDateTime myDateObj = LocalDateTime.now();
DateTimeFormatter myFormatObj = DateTimeFormatter.ofPattern("dd-MM-yyyy HH:mm:ss");
String formattedDate = myDateObj.format(myFormatObj);
```

## ✅ 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 Packages]], [[Java User Input]], [[Java Errors]]
- **참조 맥락:** java.time 패키지를 통한 날짜/시간 처리 — 에러/예외 챕터로 이어짐.

## 📚 출처 (Sources)
- [S1] W3Schools — Java Date and Time — https://www.w3schools.com/java/java_date.asp

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