Initial commit

.gitignore

+contracts/
+.classpath
+.project
+.history/
+.idea
+.jqwik-database
+.lib/
+.worksheet
+.settings/
+*.iml
+*.ipr
+*.iws
+*.log
+project/boot/
+project/plugins/project/
+project/project/
+project/*-shim.sbt
+project/target/
+target/
+openjfx/
+build/
+.gradle/
+doc/

.gitlab-ci.yml

+image: maven:latest
+
+variables:
+  # This will supress any download for dependencies and plugins or upload messages which would clutter the console log.
+  # `showDateTime` will show the passed time in milliseconds. You need to specify `--batch-mode` to make this work.
+  MAVEN_OPTS: "-Dhttps.protocols=TLSv1.2 -Dmaven.repo.local=$CI_PROJECT_DIR/.m2/repository -Dorg.slf4j.simpleLogger.log.org.apache.maven.cli.transfer.Slf4jMavenTransferListener=WARN -Dorg.slf4j.simpleLogger.showDateTime=true -Djava.awt.headless=true"
+  MAVEN_CLI_OPTS: "--batch-mode --errors --fail-at-end --show-version"
+  # -DinstallAtEnd=true -DdeployAtEnd=true"
+
+# Cache downloaded dependencies and plugins between builds.
+# To keep cache across branches add ''
+cache:
+  key: "$CI_JOB_NAME"
+  paths:
+    - .m2/repository
+
+build:
+  stage: build
+  script:
+    - mvn compile
+
+test:
+  stage: test
+  script:
+    - mvn test

README.md

+# Project description
+
+A simple hot reload system for editing live JavaFX applications without
+restarting the JVM. Requires Java 11 or later. Compatible with
+Eclipse and IntelliJ IDEA. Minor issues with Netbeans.
+
+## Installation
+
+In order to use the library, the hotreload backend library needs to be
+deployed using Maven.
+
+Maven:
+
+```bash
+$ git clone https://gitlab.utu.fi/tech/education/gui/hotreload
+
+$ cd hotreload
+
+$ mvn install
+```
+
+---
+
+## Setup
+
+To set up hotreload in your JavaFX project, the backend library
+needs to be included in project dependencies.
+
+### Maven
+
+First, add the library as a Maven dependency:
+
+```xml
+<project>
+    <dependencies>
+        <dependency>
+            <groupId>fi.utu.tech</groupId>
+            <artifactId>hotreload</artifactId>
+            <version>2.0.1</version>
+        </dependency>
+    </dependencies>
+</project>
+```
+
+### Gradle
+
+First, add the library as a Gradle dependency:
+
+```kotlin
+dependencies {
+  implementation("fi.utu.tech", "hotreload", "2.0.1")
+}
+```
+
+---
+
+## Programming API
+
+### Application class
+
+To support hot reloading, the main `Application` class should implement
+the interface `ReloadableApplication`:
+
+```java
+public interface ReloadableApplication {
+    SceneLoader getSceneLoader();
+
+    default Function<String,String> pathConverter() { return p -> p; }
+
+    default void setScene(Stage stage) {
+        ...
+    }
+
+    default void setStyleSheets(Stage stage) {
+        ...
+    }
+}
+```
+
+The default implementations for `pathConverter`,
+`setScene`, and `setStyleSheet` should work for simple projects.
+They are simply reloading the updated resources from the class and
+resource paths.
+
+The `pathConverter` is designed to rewrite resource paths
+when launching the project from IntelliJ IDEA. The demo application
+shows how to use it.
+
+The `getSceneLoader()` in `ReloadableApplication` should return a
+scene loader configuration (see below).
+
+### Scene loader configuration
+
+The `getSceneLoader()` in `ReloadableApplication` should return a
+scene loader, which is defined by the following interface:
+
+```java
+public interface SceneLoader {
+    Parent root();
+    default Controller controller() { return null; }
+    default List<String> styleSheets() { return List.of(); }
+}
+```
+
+One should define a main scene loader using this interface. The `root()`
+method should return a `Parent` object, e.g. some `Pane`. The basic idea
+is that a new `SceneLoader` implementation will be instantiated each
+time the application is reloaded. This is then used to construct the
+rest of the GUI.
+
+The `controller()` may also optionally return a new `Controller`
+object, implementing the following interface:
+
+```java
+public interface Controller {
+    default void setStage(Stage s) {}
+}
+```
+
+For instance, when initializing FXML forms, providing the stage like
+this can be useful since the default `initialize()` routine does not
+pass any values. Note that the implementation is optional.
+
+The `styleSheets` should return a list of paths to style sheet resources.
+These style sheets are then applied when the scene is reloaded.
+
+### Background monitor
+
+Finally, in order to activate the hot reload, one should initiate
+the class monitor in the `Application`'s `start()` method:
+
+```java
+
+HotReloadMonitor monitor;
+
+@Override
+public void stop() throws Exception {
+    monitor.close();
+}
+
+@Override 
+public void start(final Stage stage) {
+    try {
+        var builder = HotReloadMonitor.build(this, stage).volatilePackage(getClass().getPackageName());
+        pathConverter = builder.resourcesPathConverter();
+        monitor = builder.build();
+        monitor.start();
+    } catch (Exception e) {
+        System.err.println(e.getMessage());
+    }
+    
+    ...
+}
+```
+
+The monitor should be closed when the application is done, otherwise
+the background monitor threads will remain active.
+
+In order to initialize the application with the same scene before any
+classes have been modified, the `setScene()` method can be invoked at
+the end of the `start` method.
+
+```java
+@Override
+public void start(final Stage stage) {
+    ...
+
+    setScene(stage));
+}
+```
+
+---
+
+## Usage
+
+Once the backend library has been set up and started up properly
+in the main class, the application can be launched. The demo
+application can either use an inotify based monitor:
+        
+```
+$ ./gradlew run
+```
+
+Or listen to a socket (default port: `12345`):
+
+```
+$ ./gradlew run --args="--port=12345"
+```
+
+The build script `build.gradle.kts` has been set up to use this same
+port for notifying about the compilation in the `classes` task.
+
+### Background compiler
+
+In order to incrementally produce any class files, a background build
+task needs to be launched. Based on our experiences, due to its support
+for incremental compilation, Gradle performs much better than Maven.
+In the latest experiments, Gradle 7.1.x seems to recompile the project
+in less than 80 ms.
+
+```
+$ ./gradlew --watch-fs -t classes 
+...> Task :classes
+
+BUILD SUCCESSFUL in 85ms
+3 actionable tasks: 2 executed, 1 up-to-date
+
+Waiting for changes to input files of tasks... (ctrl-d to exit)
+modified: /tmp/hotreload/hotreload-demo/src/main/java/fi/utu/tech/demo/BoardController.java
+Change detected, executing build...
+
+> Task :classes
+
+BUILD SUCCESSFUL in 88ms
+3 actionable tasks: 2 executed, 1 up-to-date
+
+Waiting for changes to input files of tasks... (ctrl-d to exit)
+modified: /tmp/hotreload/hotreload-demo/src/main/java/fi/utu/tech/demo/BoardController.java
+Change detected, executing build...
+
+> Task :classes
+
+BUILD SUCCESSFUL in 97ms
+3 actionable tasks: 2 executed, 1 up-to-date
+
+Waiting for changes to input files of tasks... (ctrl-d to exit)
+```
+
+## Demo
+
+The video demonstrates a development session in IntelliJ IDEA. At the same time,
+a [background Gradle build task](#background-compiler) is actively searching for
+changes and recompiling the project.
+
+<a class="no-attachment-icon" href="web/hotreload.mp4" target="_blank" rel="noopener noreferrer">
+    <img src="web/hotreload.jpg" class="js-lazy-loaded qa-js-lazy-loaded">
+</a>
+
+## API documentation
+
+Online docs: <https://ftdev.utu.fi/apidocs/hotreload/>
+
+The project comes with a Doxygen configuration. Just run doxygen in the
+project root folder:
+
+```
+$ doxygen
+```
+
+The maven script will also generate standard javadoc apidocs in target/apidocs.
+
+
+## Further reading
+
+* https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/lang/ClassLoader.html
+* https://www.journaldev.com/349/java-classloader
+* https://en.wikipedia.org/wiki/Java_Classloader
+
+Hot reloading:
+
+* https://dcevm.github.io/
+* http://hotswapagent.org/index.html
+* https://github.com/bytetroll/JavaFXCSSHotReload
+* https://github.com/TravaOpenJDK/trava-jdk-11-dcevm
+* https://sites.google.com/a/athaydes.com/renato-athaydes/posts/4freewaystohot-swapcodeonthejvm
+* https://sites.google.com/a/athaydes.com/renato-athaydes/posts/saynotoelectronusingjavafxtowriteafastresponsivedesktopapplication

hotreload-demo/build.gradle.kts

+// How to use:
+//
+// $ gradle run
+// 
+// $ gradle jlink
+// $ ./build/image/bin/launch
+
+import java.io.BufferedOutputStream
+import java.io.PrintWriter
+import java.net.Socket
+
+group = "fi.utu.tech"
+version = "2.0.0"
+
+plugins {
+    java
+    //kotlin("jvm") version "1.5.21"
+    id("org.openjfx.javafxplugin") version "0.0.10"
+    id("org.beryx.jlink") version "2.24.0"
+    application
+}
+
+java {
+    sourceCompatibility = org.gradle.api.JavaVersion.VERSION_11
+
+    sourceSets["main"].java {
+        srcDir("src/main/java")
+    }
+    sourceSets["main"].resources {
+        srcDir("src/main/resources")
+    }
+    sourceSets["test"].java {
+        srcDir("src/test/java")
+    }
+    sourceSets["test"].resources {
+        srcDir("src/test/resources")
+    }
+}
+
+javafx {
+    version = "16"
+    modules = listOf("javafx.controls", "javafx.fxml", "javafx.graphics")
+}
+
+repositories {
+    mavenLocal()
+    mavenCentral()
+    maven("https://ftdev.utu.fi/maven2")
+}
+
+dependencies {
+    implementation("fi.utu.tech", "hotreload", "2.0.0")
+    //implementation("org.jetbrains.kotlin", "kotlin-stdlib-jdk8", "1.5.21")
+    testImplementation("org.junit.jupiter", "junit-jupiter-api", "5.7.1")
+    testImplementation("org.junit.jupiter", "junit-jupiter-engine", "5.7.1")
+    testImplementation("org.junit.jupiter", "junit-jupiter-params", "5.7.1")
+    testImplementation("org.junit.platform", "junit-platform-commons", "1.7.1")
+    testImplementation("net.jqwik", "jqwik", "1.5.1")
+}
+
+application {
+    mainClass.set("fi.utu.tech.demo.Main")
+    mainModule.set("fi.utu.tech.demo")
+    applicationDefaultJvmArgs = arrayListOf("-ea")
+}
+
+tasks {
+    getByName<ProcessResources>("processResources") {
+        duplicatesStrategy = DuplicatesStrategy.INCLUDE // allow duplicates
+    }
+
+    named("classes") {
+        doLast {
+            try {
+                Socket("localhost", 12345).use {
+                    PrintWriter(it.getOutputStream()).println("done")
+                }
+            } catch (e: Exception) {
+                println("Cannot connect")
+            }
+        }
+    }
+    
+    test {
+        useJUnitPlatform()
+    }
+
+    compileJava {
+        options.encoding = "UTF-8"
+    }
+}
+
+
+jlink {
+    launcher {
+        name = "launch"
+    }
+    
+    // https://github.com/beryx/badass-jlink-plugin/issues/165
+    //forceMerge("kotlin")
+}

hotreload-demo/gradle/wrapper/gradle-wrapper.properties

+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.1.1-bin.zip
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists

hotreload-demo/gradlew

+#!/usr/bin/env sh
+
+#
+# Copyright 2015 the original author or 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 UN*X
+##
+##############################################################################
+
+# Attempt to set APP_HOME
+# Resolve links: $0 may be a link
+PRG="$0"
+# Need this for relative symlinks.
+while [ -h "$PRG" ] ; do
+    ls=`ls -ld "$PRG"`
+    link=`expr "$ls" : '.*-> \(.*\)$'`
+    if expr "$link" : '/.*' > /dev/null; then
+        PRG="$link"
+    else
+        PRG=`dirname "$PRG"`"/$link"
+    fi
+done
+SAVED="`pwd`"
+cd "`dirname \"$PRG\"`/" >/dev/null
+APP_HOME="`pwd -P`"
+cd "$SAVED" >/dev/null
+
+APP_NAME="Gradle"
+APP_BASE_NAME=`basename "$0"`
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD="maximum"
+
+warn () {
+    echo "$*"
+}
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+}
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "`uname`" in
+  CYGWIN* )
+    cygwin=true
+    ;;
+  Darwin* )
+    darwin=true
+    ;;
+  MSYS* | MINGW* )
+    msys=true
+    ;;
+  NONSTOP* )
+    nonstop=true
+    ;;
+esac
+
+CLASSPATH=$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" = "false" -a "$darwin" = "false" -a "$nonstop" = "false" ] ; then
+    MAX_FD_LIMIT=`ulimit -H -n`
+    if [ $? -eq 0 ] ; then
+        if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then
+            MAX_FD="$MAX_FD_LIMIT"
+        fi
+        ulimit -n $MAX_FD
+        if [ $? -ne 0 ] ; then
+            warn "Could not set maximum file descriptor limit: $MAX_FD"
+        fi
+    else
+        warn "Could not query maximum file descriptor limit: $MAX_FD_LIMIT"
+    fi
+fi
+
+# For Darwin, add options to specify how the application appears in the dock
+if $darwin; then
+    GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
+fi
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if [ "$cygwin" = "true" -o "$msys" = "true" ] ; then
+    APP_HOME=`cygpath --path --mixed "$APP_HOME"`
+    CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
+
+    JAVACMD=`cygpath --unix "$JAVACMD"`
+
+    # We build the pattern for arguments to be converted via cygpath
+    ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null`
+    SEP=""
+    for dir in $ROOTDIRSRAW ; do
+        ROOTDIRS="$ROOTDIRS$SEP$dir"
+        SEP="|"
+    done
+    OURCYGPATTERN="(^($ROOTDIRS))"
+    # Add a user-defined pattern to the cygpath arguments
+    if [ "$GRADLE_CYGPATTERN" != "" ] ; then
+        OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)"
+    fi
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    i=0
+    for arg in "$@" ; do
+        CHECK=`echo "$arg"|egrep -c "$OURCYGPATTERN" -`
+        CHECK2=`echo "$arg"|egrep -c "^-"`                                 ### Determine if an option
+
+        if [ $CHECK -ne 0 ] && [ $CHECK2 -eq 0 ] ; then                    ### Added a condition
+            eval `echo args$i`=`cygpath --path --ignore --mixed "$arg"`
+        else
+            eval `echo args$i`="\"$arg\""
+        fi
+        i=`expr $i + 1`
+    done
+    case $i in
+        0) set -- ;;
+        1) set -- "$args0" ;;
+        2) set -- "$args0" "$args1" ;;
+        3) set -- "$args0" "$args1" "$args2" ;;
+        4) set -- "$args0" "$args1" "$args2" "$args3" ;;
+        5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
+        6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
+        7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
+        8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
+        9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
+    esac
+fi
+
+# Escape application args
+save () {
+    for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
+    echo " "
+}
+APP_ARGS=`save "$@"`
+
+# Collect all arguments for the java command, following the shell quoting and substitution rules
+eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS"
+
+exec "$JAVACMD" "$@"

hotreload-demo/gradlew.bat

+@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

hotreload-demo/pom.xml

+<project>
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>hotreload-demo</artifactId>
+    <version>2.0.1-SNAPSHOT</version>
+    <name>Hot reloader demo</name>
+    <url>https://gitlab.utu.fi/tech/education/gui/hotreload</url>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>fi.utu.tech</groupId>
+        <artifactId>hotreload-meta</artifactId>
+        <version>2.0.1</version>
+    </parent>
+
+    <properties>
+        <project.mainclass>fi.utu.tech.demo.Main</project.mainclass>
+        <hotreload.version>2.0.1</hotreload.version>
+    </properties>
+    
+    <dependencies>
+        <dependency>
+            <groupId>org.openjfx</groupId>
+            <artifactId>javafx-fxml</artifactId>
+            <version>${javafx.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>fi.utu.tech</groupId>
+            <artifactId>hotreload</artifactId>
+            <version>${hotreload.version}</version>
+        </dependency>
+    </dependencies>
+</project>

hotreload-demo/src/main/java/fi/utu/tech/demo/BoardController.java

+package fi.utu.tech.demo;
+
+import fi.utu.tech.hotreload.Controller;
+import javafx.application.Platform;
+import javafx.fxml.FXML;
+import javafx.scene.canvas.Canvas;
+import javafx.scene.canvas.GraphicsContext;
+import javafx.scene.control.*;
+import javafx.scene.image.ImageView;
+import javafx.scene.layout.HBox;
+import javafx.scene.paint.Color;
+import javafx.stage.Stage;
+
+// Example scene controller
+public class BoardController implements Controller {
+    @FXML
+    private Label status;
+
+    @FXML
+    private ImageView back;
+
+    @FXML
+    private Canvas canvas;
+
+    @FXML
+    private HBox bar;
+
+    public void initialize() {
+        setStatus("test " + this.getClass().getPackageName());
+    }
+
+    void rect(double x, double y, Color color) {
+        GraphicsContext context = canvas.getGraphicsContext2D();
+        context.setFill(color);
+        context.fillRect(x, y, 100, 100);
+    }
+
+    void circle(double x, double y, Color color) {
+        GraphicsContext context = canvas.getGraphicsContext2D();
+        context.setFill(color);
+        context.fillOval(x, y, x + 50, y + 50);
+    }
+
+    @Override
+    public void setStage(Stage s) {
+        System.out.println("Setting stage");
+        canvas.widthProperty().bind(s.getScene().widthProperty());
+        canvas.heightProperty().bind(s.getScene().heightProperty().subtract(bar.heightProperty()));
+        back.setPreserveRatio(false);
+        back.fitWidthProperty().bind(canvas.widthProperty());
+        back.fitHeightProperty().bind(canvas.heightProperty());
+
+        Platform.runLater(() -> {
+            GraphicsContext context = canvas.getGraphicsContext2D();
+            context.clearRect(0, 0, canvas.getWidth(), canvas.getHeight());
+
+            double x = 50, y = 10;
+            circle(x -= 100,50, Color.CADETBLUE);
+            rect(x += 100, y += 50, Color.RED);
+            rect(x += 20, y += 50, Color.BLUE);
+            rect(x -= 100, y += 50, Color.BLUE);
+            rect(x += 100, y += 50, Color.RED);
+            rect(x += 100, y += 50, Color.BLUE);
+            circle(x += 100,50, Color.CADETBLUE);
+        });
+    }
+
+    public void setStatus(String text) {
+        status.setText(text);
+    }
+}

hotreload-demo/src/main/java/fi/utu/tech/demo/Main.java

+package fi.utu.tech.demo;
+
+public class Main {
+    public static void main(String[] args) {
+        MainApp.launch(MainApp.class, args);
+    }
+}

hotreload-demo/src/main/java/fi/utu/tech/demo/MainApp.java

+package fi.utu.tech.demo;
+
+import fi.utu.tech.distributed.classloader.hotreload.HotReloader;
+import fi.utu.tech.hotreload.HotReloadMonitor;
+import fi.utu.tech.hotreload.ReloadableApplication;
+import fi.utu.tech.hotreload.SceneLoader;
+import javafx.application.Application;
+import javafx.stage.Stage;
+import java.util.function.Function;
+
+public class MainApp extends Application implements ReloadableApplication {
+
+    public SceneLoader getSceneLoader() {
+        return new SceneLoaderImpl();
+    }
+
+    Function<String, String> pathConverter;
+
+    @Override
+    public Function<String, String> pathConverter() {
+        return pathConverter;
+    }
+
+    HotReloadMonitor monitor;
+
+    void monitor(Stage stage, String port) {
+        try {
+            var builder =
+                    HotReloadMonitor
+                            .build(this, stage)
+                            .classRoot("hotreload-demo/"+ HotReloader.gradlePath, getClass().getPackageName())
+                            .useGradle().useIDEA();
+            if (port != null) builder.port(Integer.parseInt(port));
+            pathConverter = builder.resourcesPathConverter();
+
+            monitor = builder.build();
+
+            monitor.start();
+        } catch (Exception e) {
+            System.err.println(e.getMessage());
+        }
+    }
+
+    @Override
+    public void stop() throws Exception {
+        super.stop();
+
+        monitor.close();
+    }
+
+    @Override
+    public void start(final Stage stage) {
+        // inotify based monitoring
+        // $ gradle run
+
+        // listens to socket 12345 for messages (see the build.gradle.kts)
+        // $ gradle run --args="--port=12345"
+        String port = this.getParameters().getNamed().getOrDefault("port", null);
+
+        // activates a background process for hot reloading
+        monitor(stage, port);
+
+        stage.setResizable(true);
+        stage.show();
+        stage.setWidth(800);
+        stage.setHeight(800);
+
+        // generates the scene contents
+        // should work even without hot reloading
+        setScene(stage);
+    }
+}

hotreload-demo/src/main/java/fi/utu/tech/demo/ResourceLoader.java

+package fi.utu.tech.demo;
+
+import javafx.fxml.FXMLLoader;
+import javafx.scene.Parent;
+
+public class ResourceLoader<N extends Parent, C> {
+    public final N root;
+    public final C controller;
+
+    protected Class<?> resourceRoot() {
+        return getClass();
+    }
+
+    public ResourceLoader(String contentPath) {
+        N root_ = null;
+        C controller_ = null;
+        try {
+            // determines where to look for the resources (the root path)
+            Class<?> resourceRootClass = resourceRoot();
+
+            FXMLLoader loader = new FXMLLoader(resourceRootClass.getResource(contentPath));
+            root_ = loader.load();
+            controller_ = loader.getController();
+            //System.out.println("DEBUG: " + contentPath + " loaded.");
+        } catch (Exception e) {
+            e.printStackTrace();
+            //System.exit(1);
+        }
+        root = root_;
+        controller = controller_;
+    }
+
+    // finds resources both outside and inside jars
+    public static String locate(String fileName) {
+        return ResourceLoader.class.getResource(fileName).toExternalForm();
+    }
+}

hotreload-demo/src/main/java/fi/utu/tech/demo/SceneLoaderImpl.java

+package fi.utu.tech.demo;
+
+import fi.utu.tech.hotreload.Controller;
+import fi.utu.tech.hotreload.SceneLoader;
+import javafx.scene.Parent;
+
+import java.util.List;
+
+// Example scene configuration
+public class SceneLoaderImpl implements SceneLoader {
+    final ResourceLoader<Parent, BoardController> loader = new ResourceLoader<>("board.fxml");
+
+    public SceneLoaderImpl() {
+    }
+
+    @Override
+    public Parent root() {
+        return loader.root;
+    }
+
+    @Override
+    public Controller controller() {
+        return loader.controller;
+    }
+
+    @Override
+    public List<String> styleSheets() {
+        return List.of(ResourceLoader.locate("styles.css"));
+    }
+}

hotreload-demo/src/main/java/module-info.java

+module fi.utu.tech.demo {
+  requires transitive javafx.fxml;
+  requires fi.utu.tech.hotreload;
+  //requires kotlin.stdlib;
+  opens  fi.utu.tech.demo;
+  requires java.logging;
+  exports fi.utu.tech.demo;
+}

hotreload-demo/src/main/resources/fi/utu/tech/demo/board.fxml

+<?xml version="1.0" encoding="UTF-8"?>
+
+<?import javafx.scene.canvas.Canvas?>
+<?import javafx.scene.control.Label?>
+<?import javafx.scene.image.Image?>
+<?import javafx.scene.image.ImageView?>
+<?import javafx.scene.layout.BorderPane?>
+<?import javafx.scene.layout.HBox?>
+<?import javafx.scene.layout.StackPane?>
+
+<BorderPane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" xmlns="http://javafx.com/javafx/14.0.1" xmlns:fx="http://javafx.com/fxml/1" fx:controller="fi.utu.tech.demo.BoardController">
+   <bottom>
+      <HBox fx:id="bar" alignment="CENTER_LEFT" prefHeight="32.0" BorderPane.alignment="CENTER">
+         <children>
+            <Label fx:id="status" text="Status" />
+         </children>
+      </HBox>
+   </bottom>
+   <center>
+      <StackPane prefHeight="150.0" prefWidth="200.0" BorderPane.alignment="CENTER">
+         <children>
+            <ImageView fx:id="back" pickOnBounds="true" preserveRatio="true">
+               <image>
+                  <Image url="@alien.png" />
+               </image>
+            </ImageView>
+            <Canvas fx:id="canvas" height="200.0" width="200.0" />
+         </children>
+      </StackPane>
+   </center>
+</BorderPane>

hotreload-demo/src/main/resources/fi/utu/tech/demo/styles.css

+* {
+    -fx-background-color: white;
+}

hotreload-demo/src/test/java/fi/utu/tech/demo/DummyTest.java

+package fi.utu.tech.demo;
+
+import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class DummyTest {
+    @Test
+    public void dummy() throws Exception {
+        assertTrue(true);
+    }
+
+}