the reference answer GPT ᴼ ᴾ ᴱ ᴺ ᴬ ᴵ < br / > this problem usually because you are using Java 18, but your project configuration is not properly set up to use Java 18, Or Java 18 is not installed on your system.
To solve this problem, you can try the following steps:
- Verify that Java 18 is installed on your system and that you have added the path to Java 18 to the system environment variables.
- In your project, right-click on the project and select Properties, then select the Java Build Path TAB.
- In the Java Build Path TAB, select the Libraries TAB, and then make sure you have added the JRE library for Java 18.
- If you have not added Java 18's JRE Library to your project, you can click the "Add Library" button, select the "JRE System Library" option, then select the "Installed JREs" TAB, click the "Add" button, Then select the Java 18 installation path.
- Confirm the changes, click the Apply button, and then try to rebuild your project.
If you are still experiencing problems, make sure that your IDE is also updated to the latest version, or try reinstalling Java 18 to ensure that Java 18 is installed correctly.