Java 11

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If you run OpenXava Studio on a clean machine without Java and in a new workspace, this Java should be used by default. However, if you already have other JDKs on your computer or have a workspace where you've registered other JDKs, your application might not be using the JDK with HotswapAgent and therefore class reloading won't work.

You'll know if you're running the correct JDK if you see these lines in the log when starting your application:

HOTSWAP AGENT: 13:40:23.126 INFO (org.hotswap.agent.HotswapAgent) - Loading Hotswap agent {1.4.1} - unlimited runtime class redefinition.
Starting HotswapAgent '/home/theuser/openxava-studio-7-r4/studio/jre/lib/hotswap/hotswap-agent.jar'

If not, in OpenXava Studio, go to Window > Preferences > Java > Installed JREs and verify that you have a JRE pointing to openxava-studio-7-r4/studio/jre, as shown here:

If it's not there, add it yourself. Also, remove any other Java 11 you have registered. Try running your application again.

If it still doesn't run Java with HotswapAgent, you might have Java 1.8 recognized by OpenXava Studio and your project might be configured to work with Java 1.8, so it chooses Java 1.8 instead of Java 11 (the one from OpenXava Studio). To fix this, go to your project's pom.xml and change:

<properties>
    ...  
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
</properties>

To:

<properties>
    ...  
    <maven.compiler.source>11</maven.compiler.source>
    <maven.compiler.target>11</maven.compiler.target>
</properties>

Then right-click on your project and choose Maven > Update Project... This should make it work.

If you want to continue compiling with Java 1.8 and therefore don't want to change the pom.xml, that's not a problem. Go to Run Configurations:

Find your application and in the JRE folder, make sure your application runs with the OpenXava Studio JDK:

If not, change it - you might need to use the Alternate JRE option.

IntelliJ

You can also enjoy hot code reloading using IntelliJ. The trick is to run the application with the JDK included in OpenXava Studio 7 R4. You'll need to download OpenXava Studio, even if it's just to use its JDK.

Register the JDK included in OpenXava Studio 7 R4 in your IntelliJ. Go to File > Project Structure. There in the SDKs section add the JDK found in openxava-studio-7-r4/studio/jre:

Then in the Project section, choose this JDK as the SDK for the project:

Keep in mind that IntelliJ does not compile the code automatically when the application is running, so after changing the code you have to press the Build button, the one with the little hammer, for it to compile and be able to see the updated changes.

Visual Studio Code

To use hot code reloading with Visual Studio Code you need to run the application with the JDK included in OpenXava Studio 7 R4, so you'll need to download OpenXava Studio, even if it's just to use its JDK.
For Visual Studio Code to recognize your JDK add this to your user's settings.json:

"java.configuration.runtimes": [
    {
        "name": "JavaSE-11",
        "path": "/home/youruser/openxava-studio-7-r4/studio/jre",
        "default": true
    }
]

Visual Studio Code compiles the code automatically as you edit it, just like OpenXava Studio, so you just have to touch the code and go to the browser to see the application changed immediately.

openxava / documentation / Hot code reloading with OpenXava Studio / Java 11

Table of contents

Java included in OpenXava Studio 7 R4

IntelliJ

Visual Studio Code