Update 2
This is feedback for @OneCricketeer. Uninstalled JDK from computer, but Eclipse still able to run the Java project.
Update 2
This is feedback for @OneCricketeer. Uninstalled JDK from computer, but Eclipse still able to run the Java project.
Update
Based on answers from @M.Deinum and @OneCricketeer, I solved the problem.
In PC1, I installed JDK8, added to PATH.
The Eclipse IDE is downloaded from following link:
https://www.eclipse.org/downloads/download.php?file=/technology/epp/downloads/release/2021-03/R/eclipse-java-2021-03-R-win32-x86_64.zip When check the Configuration, it still using the default Java 15 as follow: 
So, the solution is to click Add... as in the above image, then select the installed JDK (C:\Program Files\Java\jdk1.8.0_291).
Update
Based on answers from @M.Deinum and @OneCricketeer, I solved the problem.
In PC1, I installed JDK8, added to PATH.
The Eclipse IDE is downloaded from following link:
https://www.eclipse.org/downloads/download.php?file=/technology/epp/downloads/release/2021-03/R/eclipse-java-2021-03-R-win32-x86_64.zip When check the Configuration, it still using the default Java 15 as follow:
So, the solution is to click Add... as in the above image, then select the installed JDK (C:\Program Files\Java\jdk1.8.0_291).
