The selected JRE does not support the current compliance level of 15

Event: I was told something when I looked at the Eclipse settings

--Environment --Windows10 Pro version 1903 - openjdk version "11.0.2" 2019-01-15

Cause: It is different from the Java version set in the compiler.

Looking at [Java]> [Complier], it was "15" ... Even here, it is said that When selecting 15 compliance, make sure to have a compatible JRE installed and activated (currently 11). ...

Action: Match the compiler to the version set for the installed JREs

1. Preferences dialog> Java> Compiler
2. Match [Compiler compliance level:] to the Java version set for the installed JREs> Apply with the [Apply] button
3. The messages in [Installed JREs] and [Compiler] disappear.