diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..673084a
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,43 @@
+.gradle
+build/
+!gradle/wrapper/gradle-wrapper.jar
+!**/src/main/**/build/
+!**/src/test/**/build/
+
+### IntelliJ IDEA ###
+.idea/modules.xml
+.idea/jarRepositories.xml
+.idea/compiler.xml
+.idea/libraries/
+.idea/
+*.iws
+*.iml
+*.ipr
+out/
+!**/src/main/**/out/
+!**/src/test/**/out/
+
+### Eclipse ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+bin/
+!**/src/main/**/bin/
+!**/src/test/**/bin/
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+
+### VS Code ###
+.vscode/
+
+### Mac OS ###
+.DS_Store
\ No newline at end of file
diff --git a/build.gradle.kts b/build.gradle.kts
new file mode 100644
index 0000000..b9cb47e
--- /dev/null
+++ b/build.gradle.kts
@@ -0,0 +1,26 @@
+plugins {
+ id("java")
+}
+
+group = "com"
+version = "1.0-SNAPSHOT"
+
+java {
+ toolchain {
+ languageVersion.set(JavaLanguageVersion.of(21))
+ }
+}
+
+repositories {
+ mavenCentral()
+}
+
+dependencies {
+ testImplementation(platform("org.junit:junit-bom:5.10.0"))
+ testImplementation("org.junit.jupiter:junit-jupiter")
+ implementation ("mysql:mysql-connector-java:8.0.33")
+}
+
+tasks.test {
+ useJUnitPlatform()
+}
\ No newline at end of file
diff --git a/gradle/wrapper/gradle-wrapper.jar b/gradle/wrapper/gradle-wrapper.jar
new file mode 100644
index 0000000..249e583
Binary files /dev/null and b/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
new file mode 100644
index 0000000..d427988
--- /dev/null
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -0,0 +1,6 @@
+#Fri Jan 03 00:32:13 KST 2025
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.8-bin.zip
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
diff --git a/gradlew b/gradlew
new file mode 100644
index 0000000..1b6c787
--- /dev/null
+++ b/gradlew
@@ -0,0 +1,234 @@
+#!/bin/sh
+
+#
+# Copyright © 2015-2021 the original authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+##############################################################################
+#
+# Gradle start up script for POSIX generated by Gradle.
+#
+# Important for running:
+#
+# (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is
+# noncompliant, but you have some other compliant shell such as ksh or
+# bash, then to run this script, type that shell name before the whole
+# command line, like:
+#
+# ksh Gradle
+#
+# Busybox and similar reduced shells will NOT work, because this script
+# requires all of these POSIX shell features:
+# * functions;
+# * expansions «$var», «${var}», «${var:-default}», «${var+SET}»,
+# «${var#prefix}», «${var%suffix}», and «$( cmd )»;
+# * compound commands having a testable exit status, especially «case»;
+# * various built-in commands including «command», «set», and «ulimit».
+#
+# Important for patching:
+#
+# (2) This script targets any POSIX shell, so it avoids extensions provided
+# by Bash, Ksh, etc; in particular arrays are avoided.
+#
+# The "traditional" practice of packing multiple parameters into a
+# space-separated string is a well documented source of bugs and security
+# problems, so this is (mostly) avoided, by progressively accumulating
+# options in "$@", and eventually passing that to Java.
+#
+# Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
+# and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
+# see the in-line comments for details.
+#
+# There are tweaks for specific operating systems such as AIX, CygWin,
+# Darwin, MinGW, and NonStop.
+#
+# (3) This script is generated from the Groovy template
+# https://github.com/gradle/gradle/blob/master/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+# within the Gradle project.
+#
+# You can find Gradle at https://github.com/gradle/gradle/.
+#
+##############################################################################
+
+# Attempt to set APP_HOME
+
+# Resolve links: $0 may be a link
+app_path=$0
+
+# Need this for daisy-chained symlinks.
+while
+ APP_HOME=${app_path%"${app_path##*/}"} # leaves a trailing /; empty if no leading path
+ [ -h "$app_path" ]
+do
+ ls=$( ls -ld "$app_path" )
+ link=${ls#*' -> '}
+ case $link in #(
+ /*) app_path=$link ;; #(
+ *) app_path=$APP_HOME$link ;;
+ esac
+done
+
+APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
+
+APP_NAME="Gradle"
+APP_BASE_NAME=${0##*/}
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD=maximum
+
+warn () {
+ echo "$*"
+} >&2
+
+die () {
+ echo
+ echo "$*"
+ echo
+ exit 1
+} >&2
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "$( uname )" in #(
+ CYGWIN* ) cygwin=true ;; #(
+ Darwin* ) darwin=true ;; #(
+ MSYS* | MINGW* ) msys=true ;; #(
+ NONSTOP* ) nonstop=true ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+ if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+ # IBM's JDK on AIX uses strange locations for the executables
+ JAVACMD=$JAVA_HOME/jre/sh/java
+ else
+ JAVACMD=$JAVA_HOME/bin/java
+ fi
+ if [ ! -x "$JAVACMD" ] ; then
+ die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+ fi
+else
+ JAVACMD=java
+ which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+
+# Increase the maximum file descriptors if we can.
+if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
+ case $MAX_FD in #(
+ max*)
+ MAX_FD=$( ulimit -H -n ) ||
+ warn "Could not query maximum file descriptor limit"
+ esac
+ case $MAX_FD in #(
+ '' | soft) :;; #(
+ *)
+ ulimit -n "$MAX_FD" ||
+ warn "Could not set maximum file descriptor limit to $MAX_FD"
+ esac
+fi
+
+# Collect all arguments for the java command, stacking in reverse order:
+# * args from the command line
+# * the main class name
+# * -classpath
+# * -D...appname settings
+# * --module-path (only if needed)
+# * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables.
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if "$cygwin" || "$msys" ; then
+ APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
+ CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
+
+ JAVACMD=$( cygpath --unix "$JAVACMD" )
+
+ # Now convert the arguments - kludge to limit ourselves to /bin/sh
+ for arg do
+ if
+ case $arg in #(
+ -*) false ;; # don't mess with options #(
+ /?*) t=${arg#/} t=/${t%%/*} # looks like a POSIX filepath
+ [ -e "$t" ] ;; #(
+ *) false ;;
+ esac
+ then
+ arg=$( cygpath --path --ignore --mixed "$arg" )
+ fi
+ # Roll the args list around exactly as many times as the number of
+ # args, so each arg winds up back in the position where it started, but
+ # possibly modified.
+ #
+ # NB: a `for` loop captures its iteration list before it begins, so
+ # changing the positional parameters here affects neither the number of
+ # iterations, nor the values presented in `arg`.
+ shift # remove old arg
+ set -- "$@" "$arg" # push replacement arg
+ done
+fi
+
+# Collect all arguments for the java command;
+# * $DEFAULT_JVM_OPTS, $JAVA_OPTS, and $GRADLE_OPTS can contain fragments of
+# shell script including quotes and variable substitutions, so put them in
+# double quotes to make sure that they get re-expanded; and
+# * put everything else in single quotes, so that it's not re-expanded.
+
+set -- \
+ "-Dorg.gradle.appname=$APP_BASE_NAME" \
+ -classpath "$CLASSPATH" \
+ org.gradle.wrapper.GradleWrapperMain \
+ "$@"
+
+# Use "xargs" to parse quoted args.
+#
+# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
+#
+# In Bash we could simply go:
+#
+# readarray ARGS < <( xargs -n1 <<<"$var" ) &&
+# set -- "${ARGS[@]}" "$@"
+#
+# but POSIX shell has neither arrays nor command substitution, so instead we
+# post-process each arg (as a line of input to sed) to backslash-escape any
+# character that might be a shell metacharacter, then use eval to reverse
+# that process (while maintaining the separation between arguments), and wrap
+# the whole thing up as a single "set" statement.
+#
+# This will of course break if any of these variables contains a newline or
+# an unmatched quote.
+#
+
+eval "set -- $(
+ printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" |
+ xargs -n1 |
+ sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' |
+ tr '\n' ' '
+ )" '"$@"'
+
+exec "$JAVACMD" "$@"
diff --git a/gradlew.bat b/gradlew.bat
new file mode 100644
index 0000000..107acd3
--- /dev/null
+++ b/gradlew.bat
@@ -0,0 +1,89 @@
+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+
+@if "%DEBUG%" == "" @echo off
+@rem ##########################################################################
+@rem
+@rem Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%" == "" set DIRNAME=.
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if "%ERRORLEVEL%" == "0" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
+
+:end
+@rem End local scope for the variables with windows NT shell
+if "%ERRORLEVEL%"=="0" goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+if not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
+exit /b 1
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega
diff --git a/settings.gradle.kts b/settings.gradle.kts
new file mode 100644
index 0000000..fb67571
--- /dev/null
+++ b/settings.gradle.kts
@@ -0,0 +1,2 @@
+rootProject.name = "pre-homwork"
+
diff --git a/src/main/java/Main.java b/src/main/java/Main.java
new file mode 100644
index 0000000..1978d78
--- /dev/null
+++ b/src/main/java/Main.java
@@ -0,0 +1,15 @@
+//TIP 코드를 실행하려면 을(를) 누르거나
+// 에디터 여백에 있는 아이콘을 클릭하세요.
+public class Main {
+ public static void main(String[] args) {
+ //TIP 캐럿을 강조 표시된 텍스트에 놓고 을(를) 누르면
+ // IntelliJ IDEA이(가) 수정을 제안하는 것을 확인할 수 있습니다.
+ System.out.printf("Hello and welcome!");
+
+ for (int i = 1; i <= 5; i++) {
+ //TIP 을(를) 눌러 코드 디버그를 시작하세요. 1개의 중단점을 설정해 드렸습니다
+ // 언제든 을(를) 눌러 중단점을 더 추가할 수 있습니다.
+ System.out.println("i = " + i);
+ }
+ }
+}
diff --git a/src/main/java/thread/Item.java b/src/main/java/thread/Item.java
new file mode 100644
index 0000000..1af273c
--- /dev/null
+++ b/src/main/java/thread/Item.java
@@ -0,0 +1,53 @@
+package thread;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
+
+public class Item {
+ private String itemName;
+ private int stock;
+ private final Lock lock = new ReentrantLock(); // 동시성 문제 해결을 위한 Lock 사용
+
+ public Item(String itemName, int stock) {
+ this.itemName = itemName;
+ this.stock = stock;
+
+ }
+
+ public String getItemName() {
+ return itemName;
+ }
+
+ public void setItemName(String itemName) {
+ this.itemName = itemName;
+ }
+
+ public int getStock() {
+ return stock;
+ }
+
+ public void setStock(int stock) {
+ this.stock = stock;
+ }
+
+ /**
+ * @brief 구매한 아이템의 재고를 감소한다.
+ * @param cnt 구매할 개수
+ */
+ public void buyItems(int cnt) {
+ lock.lock();
+ try{
+ if (cnt > stock) {
+ System.out.println(Thread.currentThread().getName() + " - shortage of stock !");
+ } else {
+ this.stock -= cnt;
+ System.out.println(Thread.currentThread().getName() + " - purchase: " + cnt + " (stock: "+ this.stock + ")");
+ }
+ } finally {
+ lock.unlock();
+ }
+ }
+}
diff --git a/src/main/java/thread/LatestOrderDatabase.java b/src/main/java/thread/LatestOrderDatabase.java
new file mode 100644
index 0000000..7970884
--- /dev/null
+++ b/src/main/java/thread/LatestOrderDatabase.java
@@ -0,0 +1,29 @@
+package thread;
+
+public class LatestOrderDatabase {
+ private String userName;
+ private String itemName;
+ private int orderAmount;
+
+ public LatestOrderDatabase(String userName, String itemName, int orderAmount) {
+ this.userName = userName;
+ this.itemName = itemName;
+ this.orderAmount = orderAmount;
+ }
+
+ public String getUserName() {
+ return userName;
+ }
+
+ public String getItemName() {
+ return itemName;
+ }
+
+ public int getOrderAmount() {
+ return orderAmount;
+ }
+
+ public String getLatestOrderInfo() {
+ return "User : " + this.userName + ", Item : " + this.itemName + ", Order Amount : " + this.orderAmount;
+ }
+}
diff --git a/src/main/java/thread/MyshopMain.java b/src/main/java/thread/MyshopMain.java
new file mode 100644
index 0000000..c82f51a
--- /dev/null
+++ b/src/main/java/thread/MyshopMain.java
@@ -0,0 +1,58 @@
+package thread;
+
+import java.util.Map;
+import java.util.Random;
+import java.util.concurrent.ConcurrentHashMap;
+
+public class MyshopMain {
+
+ // 동시성 문제가 발생할 수 있는 스레드를 재현한다.
+ // Lock을 사용하지 않을 경우, 남은 사과 개수가 예상 개수보다 많았다. (ex. 예상: 60개, 결과 68개)
+ // Lock을 사용하였을 경우, 남은 사과 개수가 예상 개수와 일치하였다.
+
+ public static void main(String[] args) {
+ // 재고 세팅
+ Item apple = new Item("apple", 100);
+
+ Map latestorderMap = new ConcurrentHashMap<>();
+ Random random = new Random();
+
+ // 스레드 수행 업무
+ Runnable buyTask = () -> {
+ int orderAmount = random.nextInt(11);
+ LatestOrderDatabase order = new LatestOrderDatabase(Thread.currentThread().getName(), "apple", orderAmount);
+ latestorderMap.put(Thread.currentThread().getName(), order.getLatestOrderInfo());
+ apple.buyItems(orderAmount);
+
+ try{
+ Thread.sleep(100);
+ } catch (InterruptedException e) {
+ Thread.currentThread().interrupt();
+ }
+
+ };
+
+ // 스레드 생성 및 실행
+ Thread[] threads = new Thread[5];
+ for (int i = 0; i < threads.length; i++) {
+ threads[i] = new Thread(buyTask, "Thread" + (i+1));
+ threads[i].start();
+ }
+
+ // 메인 스레드에서 모든 작업이 완료될 때까지 대기
+ for (Thread thread : threads) {
+ try {
+ thread.join();
+ } catch (InterruptedException e) {
+ Thread.currentThread().interrupt();
+ }
+ }
+
+ // 최종 재고 확인
+ System.out.println("FINAL STOCKED APPLE : " + apple.getStock());
+
+ // 사용자별 최종 구매 아이템 확인
+// System.out.println("LAST ORDER LIST FOR USER : " + latestorderMap);
+ }
+
+}
diff --git a/src/test/java/MyshopMainTest.java b/src/test/java/MyshopMainTest.java
new file mode 100644
index 0000000..16832bf
--- /dev/null
+++ b/src/test/java/MyshopMainTest.java
@@ -0,0 +1,57 @@
+import org.junit.jupiter.api.Test;
+import thread.Item;
+import thread.LatestOrderDatabase;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.CountDownLatch;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+
+public class MyshopMainTest {
+
+ @Test
+ void testConcurrentBuyItems() throws InterruptedException {
+ // 재고 세팅
+ Item apple = new Item("apple", 100);
+
+ Map latestOrderMap = new ConcurrentHashMap<>();
+
+ // 스레드 동기화 처리를 위한 CountDownLatch
+ int numThreads = 100;
+ CountDownLatch latch = new CountDownLatch(numThreads);
+
+ // 스레드 수행 업무
+ Runnable buyTask = () -> {
+ try {
+ int orderAmount = 8;
+ apple.buyItems(orderAmount);
+ LatestOrderDatabase order = new LatestOrderDatabase(Thread.currentThread().getName(), "apple", orderAmount);
+ latestOrderMap.put(Thread.currentThread().getName() ,order.getLatestOrderInfo());
+
+ // 스레드 종료 대기
+ latch.countDown();
+ } catch (Exception e) {
+ e.printStackTrace();
+ }
+ };
+
+ // 스레드 생성 및 실행
+ Thread[] threads = new Thread[numThreads];
+ for (int i = 0; i < threads.length; i++) {
+ threads[i] = new Thread(buyTask, "Thread" + (i+1));
+ threads[i].start();
+ }
+
+ // 메인 스레드에서 모든 작업이 완료될 때까지 대기
+ latch.await(); // 모든 스레드가 작업을 완료할 때까지 대기
+
+ // 최종 재고 확인
+ assertEquals(4, apple.getStock(), "Final stock should match expected value after orders");
+
+ // 여기서 최종 주문 내역 확인
+ assertNotNull(latestOrderMap, "Order map should not be null");
+ assertEquals(numThreads, latestOrderMap.size(), "There should be exactly 100 orders placed.");
+ }
+}