To use the var keyword with JDK 10 in NetBeans:
- Ensure that you are running the latest version of Apache NetBeans.
- In NetBeans add JDK 10 as a Java platform (Tools > Java Platforms > Add Plaform...). It is not necessary to make JDK 10 the default.
- Create a simple Java application (File > New Project... > Java > Java Application) and declare a var variable (e.g.
var v = 7;) within the main() method.
- Select the project node in the Projects pane, right click and select Properties.
- In the Project Properties window ensure that Libraries > Java Platform is set to JDK 10
- In the Project Properties window ensure that Sources > Source/Binary Format is set to JDK 10
- In the Files pane open the file project.properties (under the nbproject folder) and navigate to the lines for
javac.source and javac.target. Verify that they both contain the value 10.
- Press Shift-F11 to clean and build the project.
If there is still a "cannot find symbol" error for the var declaration then there is something fundamentally wrong with the NetBeans installation, so update the OP with:
- The content of the Output window after doing the Clean and Build.
- The source being compiled.
- The settings for
javac.source and javac.target in project.properties.
- The version information shown in the Help > About window.