Java swing on eclipse oxygen 4.7.3a?

Question

I am trying to use windowbuilder on eclipse oxygen 4.7.3a on macOS highSierra. it installed fine but every time I try to open the design part it displays this error

Eclipse is running under 0, but this Java project has a 1.8 Java compliance level, so WindowBuilder will not be able to load classes from this project. Use a lower level of Java for the project, or run Eclipse using a newer Java version.

I tried everything. like changing the running enviroment, .jre files, try different JDE. nothing working. any suggestions?

Answer 1

Your only short term solution is to use a Java version <= 9.

Initially WindowBuilder did not work with Java 9 for several reasons. See Bug 526098 - WindowBuilder fails to work on Java 9.

One of those issues was that the the System Property java.version was unexpectedly just "9":

Please check that you have exactly 9.0 JDK, it worked for me with 9.0.1 until I downgraded target JRE to 9.0, which has unusual System.getProperty("java.version").equals("9")

The fixes to get WindowsBuilder working on Java 9 were only completed on 2/21/18, and based on your error it looks like a similar issue exists when running WindowsBuilder using Java 10. I suggest you create a Bug Report with Eclipse.

See also:

• SO Post Eclipse Oxygen Window Builder Error with Java SE 10.0.1 where the solution/workaround was to regress to Java 9.
• This Eclipse Forum post where a user is reporting a similar problem to yours.