Here is a complete list of steps - you may not need steps 1-3 but am including them for completeness:-

1. Download VS Code and Apache Maven and install both.
2. Install the Visual Studio extension pack for Java - e.g. by pasting this URL into a web browser: vscode:extension/vscjava.vscode-java-pack and then clicking on the green Install button after it opens in VS Code.
3. NOTE: See the comment from ADTC for an "Easier GUI version of step 3...(Skip step 4)." If necessary, the Maven quick start archetype could be used to generate a new Maven project in an appropriate local folder: mvn archetype:generate -DgroupId=com.companyname.appname -DartifactId=appname -DarchetypeArtifactId=maven-archetype-quickstart -DinteractiveMode=false. This will create an appname folder with Maven's Standard Directory Layout (i.e. src/main/java/com/companyname/appname and src/main/test/com/companyname/appname to begin with and a sample "Hello World!" Java file named appname.java and associated unit test named appnameTest.java).*
4. Open the Maven project folder in VS Code via File menu -> Open Folder... and select the appname folder.
5. Open the Command Palette (via the View menu or by right-clicking) and type in and select Tasks: Configure task then select Create tasks.json from template.
6. Choose maven ("Executes common Maven commands"). This creates a tasks.json file with "verify" and "test" tasks. More can be added corresponding to other Maven Build Lifecycle phases. To specifically address your requirement for classes to be built without a JAR file, a "compile" task would need to be added as follows:

    {
        "label": "compile",
        "type": "shell",
        "command": "mvn -B compile",
        "group": "build"
    },

7. Save the above changes and then open the Command Palette and select "Tasks: Run Build Task" then pick "compile" and then "Continue without scanning the task output". This invokes Maven, which creates a target folder at the same level as the src folder with the compiled class files in the target\classes folder.

Addendum: How to run/debug a class

Following a question in the comments, here are some steps for running/debugging:-

1. Show the Debug view if it is not already shown (via View menu - Debug or CtrlShiftD).
2. Click on the green arrow in the Debug view and select "Java".
3. Assuming it hasn't already been created, a message "launch.json is needed to start the debugger. Do you want to create it now?" will appear - select "Yes" and then select "Java" again.
4. Enter the fully qualified name of the main class (e.g. com.companyname.appname.App) in the value for "mainClass" and save the file.
5. Click on the green arrow in the Debug view again.

Here are some steps:

1. Tell VS Code to use Maven.
2. Add a pom.xml to your project to spell out the dependencies.
3. Ask Maven to download the dependencies to your local .m2 repository.
4. Use the Maven lifecycle to compile/test/package your code.

You'll have no problem as long as all the JARs you need are in Maven Central. If some of them were internal to your organization you'll have to find them and pull them from a private repo or add them to your local .m2.

If this is an old Java project you might want to think about updating. Check the JARs for security vulnerabilities and upgrade them if you can. Hopefully there will be a good Junit suite to prove that upgrades didn't break your code.

One last suggestion: Try to compile and run it on a LTS version of the JDK - 11 or 17. Don't continue with JDK 8 - it's past the end of its support life.

This is easy in IntelliJ. I'd prefer it to VS Code.

When you run java --version in integrated Terminal in VS Code, it will search JAVA_HOME set in Environment Variables, so it's still jdk1.8.

But when you run the file like helloworld.java, the execution scripts shown in Terminal should include C:\Program Files\Java\jdk-11.0.7+10_hotspot\bin\java.exe, which means java extension tools indeed uses jdk11 to build and compile projects.

About maven, you still need to add it to PATH, then mvn --version should work in Terminal:

If you set "maven.terminal.useJavaHome": true,, it will use JAVA_HOME in Environment Variables which is JDK1.8, you can specify jdk version with the following two ways:

1. When you create a maven project, you can choose jdk version manually;

2. In Maven projects' pom.xml, don't forget to rebuild the project:

    <properties>
        <java.version>11</java.version>
    </properties>
   

   More information view Apache Maven Compiler Plugin – Setting the -source and -target of the Java Compiler.