2nd/10_Wiki/Dev/Topic_Java/Java_Packages.md

id, title, category, status, verification_status, canonical_id, aliases, duplicate_of, source_trust_level, confidence_score, created_at, updated_at, review_reason, merge_history, tags, raw_sources, applied_in, github_commit

id	title	category	status	verification_status	canonical_id	aliases	duplicate_of	source_trust_level	confidence_score	created_at	updated_at	review_reason	merge_history	tags	raw_sources	applied_in	github_commit
java-packages	Java Packages	Programming_Language	draft	conceptual		import keyword 자바 패키지		B	0.88	2026-07-04	2026-07-04			java programming w3schools oop packages import	https://www.w3schools.com/java/java_packages.asp

Java Packages

🎯 한 줄 통찰 (One-line insight)

Building your own package requires a two-step compile that most beginners miss — first javac MyPackageClass.java, then javac -d . MyPackageClass.java (the -d flag actually creates the package's folder structure); skipping the second step means the package folder never materializes. [S1]

🧠 핵심 개념 (Core concepts)

• Package — groups related classes, like a folder; avoids name conflicts, improves maintainability. [S1]
• Built-in packages — the Java API, a library of prewritten classes (e.g. java.util). [S1]
• User-defined packages — created via the package keyword, mapped to actual filesystem directories. [S1]
• import — import package.name.Class; for a single class, import package.name.*; for the whole package. [S1]
• -d compiler flag — specifies the destination folder, forcing the compiler to create the package directory structure. [S1]
• Lowercase package naming convention — avoids conflicts with class names (which start uppercase). [S1]

📖 세부 내용 (Details)

• Import a single class: import java.util.Scanner; ... Scanner myObj = new Scanner(System.in); String userName = myObj.nextLine();. [S1]
• Import whole package: import java.util.*;. [S1]
• User-defined package: package mypack; class MyPackageClass { public static void main(String[] args) { System.out.println("This is my package!"); } }. [S1]
• Compile + run: javac MyPackageClass.java then javac -d . MyPackageClass.java, then run via java mypack.MyPackageClass. [S1]

⚖️ 모순 및 업데이트 (Contradictions & updates)

소스에서 모순되는 정보는 발견되지 않음.

🛠️ 적용 사례 (Applied in summary)

현재 발견된 실제 적용 사례가 없습니다 — Scanner 클래스를 이용한 사용자 입력 처리가 java.util 패키지 활용의 대표 실전 사례다. [S1]

💻 코드 패턴 (Code patterns)

Using Scanner from java.util for user input (Java):

import java.util.Scanner;
class Main {
    public static void main(String[] args) {
        Scanner myObj = new Scanner(System.in);
        System.out.println("Enter username");
        String userName = myObj.nextLine();
        System.out.println("Username is: " + userName);
    }
}

✅ 검증 상태 및 신뢰도

• 상태: draft
• 검증 단계: conceptual
• 출처 신뢰도: B (W3Schools — widely used educational reference, not a primary standards body)
• 신뢰 점수: 0.88
• 중복 검사 결과: 신규 생성 (New discovery)

🔗 지식 그래프 (Knowledge Graph)

• 상위/루트: Java Tutorial
• 관련 개념: Java Encapsulation, Java Inheritance, Java User Input
• 참조 맥락: 클래스 그룹화 및 import 문법 — 사용자 입력(Scanner)/상속 챕터로 이어짐.

📚 출처 (Sources)

• [S1] W3Schools — Java Packages & API — https://www.w3schools.com/java/java_packages.asp

📝 변경 이력 (Change history)

• 2026-07-04: Initial draft synthesized from the W3Schools "Java Packages & API" page (Astra wiki-curation, P-Reinforce v3.1 format).