Feature/runner

.github/workflows/ci.yaml

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+name: CI
+
+on:
+  push:
+    branches: [ main, dev ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+
+  # ── Linux ────────────────────────────────────────────────────
+  test-linux:
+    name: Test on Linux
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up JDK 21
+        uses: actions/setup-java@v4
+        with:
+          java-version: '21'
+          distribution: 'temurin'
+
+      - name: Make runner executable
+        run: chmod +x runner.sh
+
+      - name: Run HelloWorld
+        run: ./runner.sh examples/HelloWorld.java
+
+      - name: Run FizzBuzz
+        run: ./runner.sh examples/FizzBuzz.java
+
+      - name: Run auto-detect from examples/
+        run: |
+          mkdir -p /tmp/test-autodetect
+          cp examples/HelloWorld.java /tmp/test-autodetect/
+          cd /tmp/test-autodetect
+          bash "$GITHUB_WORKSPACE/runner.sh"
+
+  # ── macOS ────────────────────────────────────────────────────
+  test-macos:
+    name: Test on macOS
+    runs-on: macos-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up JDK 21
+        uses: actions/setup-java@v4
+        with:
+          java-version: '21'
+          distribution: 'temurin'
+
+      - name: Make runner executable
+        run: chmod +x runner.sh
+
+      - name: Run HelloWorld
+        run: ./runner.sh examples/HelloWorld.java
+
+      - name: Run FizzBuzz
+        run: ./runner.sh examples/FizzBuzz.java
+
+  # ── Windows ──────────────────────────────────────────────────
+  test-windows:
+    name: Test on Windows
+    runs-on: windows-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up JDK 21
+        uses: actions/setup-java@v4
+        with:
+          java-version: '21'
+          distribution: 'temurin'
+
+      - name: Run HelloWorld
+        run: .\runner.bat examples\HelloWorld.java
+
+      - name: Run FizzBuzz
+        run: .\runner.bat examples\FizzBuzz.java
+
+      - name: Run auto-detect from examples\
+        run: |
+          New-Item -ItemType Directory -Force -Path "$env:TEMP\test-autodetect"
+          Copy-Item examples\HelloWorld.java "$env:TEMP\test-autodetect\"
+          Set-Location "$env:TEMP\test-autodetect"
+          & "$env:GITHUB_WORKSPACE\runner.bat"
+        shell: pwsh

examples/HelloWorld.java

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+public class HelloWorld {
+    public static void main(String[] args) {
+        System.out.println("Hello, World!");
+        System.out.println("java-runner is working correctly.");
+    }
+}

runner.bat

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+@echo off
+REM ─────────────────────────────────────────────────────────────
+REM  java-runner - run Java exercises without an IDE (Windows)
+REM  Usage: runner.bat [File.java] [--watch]
+REM ─────────────────────────────────────────────────────────────
+
+setlocal EnableDelayedExpansion
+
+set "FILE="
+set "WATCH=false"
+
+REM ── Parse arguments ───────────────────────────────────────────
+for %%A in (%*) do (
+  if "%%A"=="--watch" set "WATCH=true"
+  if "%%~xA"==".java" set "FILE=%%A"
+  if "%%A"=="--help" goto :help
+  if "%%A"=="-h" goto :help
+)
+
+REM ── Auto-detect .java file ────────────────────────────────────
+if "%FILE%"=="" (
+  set "count=0"
+  for %%F in (*.java) do (
+    set "FILE=%%F"
+    set /a count+=1
+  )
+
+  REM If none found in current dir, fall back to examples\
+  if "!count!"=="0" (
+    if exist examples\ (
+      echo [INFO] No .java in current dir, searching examples\
+      for %%F in (examples\*.java) do (
+        set "FILE=%%F"
+        set /a count+=1
+      )
+    )
+  )
+
+  if "!count!"=="0" (
+    echo [ERROR] No .java file found in current directory or examples\
+    exit /b 1
+  )
+  if !count! GTR 1 (
+    echo [WARNING] Multiple .java files found. Please specify one:
+    for %%F in (*.java) do echo   %%F
+    if exist examples\ for %%F in (examples\*.java) do echo   %%F
+    exit /b 1
+  )
+)
+
+REM ── Validate file exists ──────────────────────────────────────
+if not exist "%FILE%" (
+  echo [ERROR] File not found: %FILE%
+  exit /b 1
+)
+
+REM ── Watch mode ────────────────────────────────────────────────
+if "%WATCH%"=="true" (
+  echo [WATCH] Watch mode enabled - save the file to rerun
+  :watchloop
+  call :run
+  echo [WATCH] Waiting for changes... Press Ctrl+C to stop.
+  REM Poll every 2 seconds (Windows has no native inotify)
+  timeout /t 2 /nobreak >nul
+  goto :watchloop
+)
+
+call :run
+exit /b
+
+REM ── Help ──────────────────────────────────────────────────────
+:help
+echo Usage: runner.bat [File.java] [--watch]
+echo   File.java   Java file to compile and run
+echo   --watch     Recompile and rerun every 2 seconds
+exit /b
+
+REM ── Main run function ─────────────────────────────────────────
+:run
+  for %%F in ("%FILE%") do set "CLASSNAME=%%~nF"
+  set "TMPDIR=%TEMP%\java-runner-%RANDOM%"
+  mkdir "%TMPDIR%" 2>nul
+
+  echo.
+  echo [....] Compiling %CLASSNAME%.java...
+
+  javac -d "%TMPDIR%" "%FILE%" 2>"%TMPDIR%\errors.txt"
+  if errorlevel 1 (
+    echo [FAIL] Compilation failed:
+    echo.
+    type "%TMPDIR%\errors.txt"
+    rmdir /s /q "%TMPDIR%"
+    exit /b 1
+  )
+
+  echo [ OK ] Compiled successfully
+  echo ───────────────────────── output ─────────────────────────
+
+  set "START_TIME=%TIME%"
+  java -cp "%TMPDIR%" "%CLASSNAME%"
+  set "END_TIME=%TIME%"
+
+  echo ───────────────────────────────────────────────────────────
+  echo [ OK ] Done
+  echo.
+
+  rmdir /s /q "%TMPDIR%"
+  exit /b

runner.sh

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+#!/usr/bin/env bash
+# ─────────────────────────────────────────────────────────────
+#  java-runner - run Java exercises without an IDE
+#  Usage: ./runner.sh [File.java] [--watch]
+# ─────────────────────────────────────────────────────────────
+
+set -euo pipefail
+
+# ── Colors ────────────────────────────────────────────────────
+RED='\033[0;31m'
+GREEN='\033[0;32m'
+YELLOW='\033[1;33m'
+CYAN='\033[0;36m'
+RESET='\033[0m'
+
+# ── Detect OS ─────────────────────────────────────────────────
+OS="$(uname -s)"
+case "$OS" in
+  Linux*)  PLATFORM="linux" ;;
+  Darwin*) PLATFORM="mac" ;;
+  *)       PLATFORM="unknown" ;;
+esac
+
+# ── Arguments ─────────────────────────────────────────────────
+FILE=""
+WATCH=false
+
+for arg in "$@"; do
+  case $arg in
+    --watch) WATCH=true ;;
+    *.java)  FILE="$arg" ;;
+    --help|-h)
+      echo -e "Usage: ./runner.sh [File.java] [--watch]"
+      echo -e "  File.java   Java file to compile and run (optional if only one .java exists)"
+      echo -e "  --watch     Recompile and rerun on every file save"
+      exit 0
+      ;;
+  esac
+done
+
+# ── Auto-detect .java file ────────────────────────────────────
+if [[ -z "$FILE" ]]; then
+  mapfile -t found < <(find . -maxdepth 1 -name "*.java")
+
+  # If none in current dir, fall back to examples/
+  if [[ ${#found[@]} -eq 0 ]] && [[ -d "./examples" ]]; then
+    mapfile -t found < <(find ./examples -maxdepth 1 -name "*.java")
+    [[ ${#found[@]} -gt 0 ]] && echo -e "${YELLOW}⚠ No .java in current dir, searching examples/${RESET}"
+  fi
+
+  if [[ ${#found[@]} -eq 1 ]]; then
+    FILE="${found[0]}"
+  elif [[ ${#found[@]} -eq 0 ]]; then
+    echo -e "${RED}✗ No .java file found in current directory or examples/${RESET}"
+    exit 1
+  else
+    echo -e "${YELLOW}⚠ Multiple .java files found. Please specify one:${RESET}"
+    printf '  %s\n' "${found[@]}"
+    exit 1
+  fi
+fi
+
+# ── Validate file exists ──────────────────────────────────────
+if [[ ! -f "$FILE" ]]; then
+  echo -e "${RED}✗ File not found: $FILE${RESET}"
+  exit 1
+fi
+
+# ── Main run function ─────────────────────────────────────────
+run() {
+  local classname
+  classname=$(basename "$FILE" .java)
+  local tmpdir
+  tmpdir=$(mktemp -d)
+
+  echo -e ""
+  echo -e "${CYAN}▶  Compiling ${classname}.java...${RESET}"
+
+  # Compile - capture errors
+  if ! javac -d "$tmpdir" "$FILE" 2>"$tmpdir/errors.txt"; then
+    echo -e "${RED}✗  Compilation failed:${RESET}\n"
+    # Strip absolute path noise
+    sed "s|$PWD/||g" "$tmpdir/errors.txt"
+    rm -rf "$tmpdir"
+    return 1
+  fi
+
+  echo -e "${GREEN}✓  Compiled successfully${RESET}"
+  echo -e "${CYAN}───────────────────────── output ─────────────────────────${RESET}"
+
+  # Run and measure time
+  local start
+  start=$(date +%s%N 2>/dev/null || date +%s)
+  java -cp "$tmpdir" "$classname"
+  local end
+  end=$(date +%s%N 2>/dev/null || date +%s)
+
+  # Calculate elapsed (nanoseconds if available, else seconds)
+  local elapsed
+  if [[ ${#start} -gt 10 ]]; then
+    elapsed=$(( (end - start) / 1000000 ))
+    echo -e "${CYAN}───────────────────────────────────────────────────────────${RESET}"
+    echo -e "${GREEN}✓  Finished in ${elapsed}ms${RESET}\n"
+  else
+    elapsed=$(( end - start ))
+    echo -e "${CYAN}───────────────────────────────────────────────────────────${RESET}"
+    echo -e "${GREEN}✓  Finished in ${elapsed}s${RESET}\n"
+  fi
+
+  rm -rf "$tmpdir"
+}
+
+# ── Watch mode ────────────────────────────────────────────────
+if $WATCH; then
+  echo -e "${YELLOW}👁  Watch mode enabled - save the file to rerun${RESET}"
+  run || true
+
+  if [[ "$PLATFORM" == "linux" ]]; then
+    if ! command -v inotifywait &>/dev/null; then
+      echo -e "${RED}✗  inotifywait not found. Install it with: sudo apt install inotify-tools${RESET}"
+      exit 1
+    fi
+    while inotifywait -q -e close_write "$FILE"; do
+      echo -e "\n${YELLOW}↻  Change detected...${RESET}"
+      run || true
+    done
+
+  elif [[ "$PLATFORM" == "mac" ]]; then
+    if ! command -v fswatch &>/dev/null; then
+      echo -e "${RED}✗  fswatch not found. Install it with: brew install fswatch${RESET}"
+      exit 1
+    fi
+    fswatch -o "$FILE" | while read -r; do
+      echo -e "\n${YELLOW}↻  Change detected...${RESET}"
+      run || true
+    done
+
+  else
+    echo -e "${RED}✗  Watch mode is not supported on this platform${RESET}"
+    exit 1
+  fi
+
+else
+  run
+fi