How to try Java preview features (such as Java 15 Record) in IntelliJ

Conclusion

1. (Update to the latest version of IntelliJ IDEA)
2. Set the project to use the relevant JDK
3. Download the JDK you want to use
4. Turn on the preview function 2. File>Project Structure>Project Settings>Modules
5. Select " 15 (Preview) --Sealed types, records, patterns, local enums and interfaces "in Language level

• The above is for a Windows environment. For Mac, the way to open Project Structure is slightly different.
• You can also open Project Structure with "Ctrl" + "Shift" + "Alt" + "S".

environment

• Windows --IntelliJ IDEA Community version (2020.2.2)
• Open JDK15

Detailed procedure

1. Update to the latest version of IntelliJ IDEA

New features in Java 15 require IntelliJ newer than 2020.2. Click here for 2020.2 update information If the version is old, please update it by the following method.

Automatic update

You can update automatically from Help> Check for Updates ... Press the ʻupdate and restart` button and wait and you're done.

• If the ʻupdate and restart` button is not displayed, perform a manual update.

Manual update

Download and update the specified version of the file from here You can also. The installation wizard will ask you if you want to erase the old version and keep the settings.

2. Set the project to use the relevant JDK

Open IntelliJ and create a new project. If you select Download JDK from the pull-down, the selected distribution and version of the JDK will be set as the JDK used in your project. If you want to use the Early Access version that is not displayed here, please specify the JDK downloaded by "Add JDK ..." after downloading by yourself. (Specify the directory where bin and lib are located.)

3. Turn on the preview function

Open File> Project Structure> Project Settings> Modules. From the Language level pull-down, specify the one that matches the function you want to use. Since I will try records this time, I specified " 15 (Preview) --Sealed types, records, patterns, local enums and interfaces ".

If Java 15 is not set, please check the IntelliJ version and Java version again.

Try to run

First, create a Record class.

package records;

public record ExampleRecord(String name, int age) {
}

Next, create a Main class to execute.

package main;

import records.ExampleRecord;

public class Main {
  public static void main(String[] args) {
    ExampleRecord exampleRecord = new ExampleRecord("test", 20);
    System.out.println(exampleRecord);
  }
}

When I run it, it looks like this!

{JDK_path}\bin\java.exe --enable-preview "-javaagent:{IntelliJ IDEA_path}\lib\idea_rt.jar=50507:{IntelliJ IDEA_path}\bin" -Dfile.encoding=UTF-8 -classpath {workspace_path}\{project_name}\out\production\record_refrection main.Main
ExampleRecord[name=test, age=20]

The point is that --enable-preview is given as an option. This allows you to use the preview function Record. That's it.