Determining the JRE System Library

These instructions are for Eclipse 2020-06 (which is installed on the PCs in KEC 119 and KEC 123). The instructions will be similar for other versions of Eclipse - but there might be some slight differences.

All of the labs have been reconfigured to use JRE System Library[JavaSE-1.8], which is installed on the PC’s in both KEC 119 and KEC 123. It is possible that the configuration you are using on your own PC (or even on a lab PC) could vary such that no suitable version of Java JRE 1.8 can be found. The instructions below will help you establish the proper JRE System Libraries for the labs for CS320.

If you are using an older version of the JRE System Library, you might need to change the default JRE System Library version to a later version in order to get CS320_Lab02 to work. A JRE System Library version of jre1.8.0_181 or later (up to 1.8.0_301) should work fine - choose the latest version in that range that you have available.

In KEC 119 and KEC 123, the latest version of the JRE System Library is 1.8.0_301. I recommend using the same version as installed on the lab PCs.

Create a folder on your YCP home drive (H:) or on your own PC (C:) named cs320-spring2022.
Set the Default Workspace for Eclipse to that location.
Download CS320_Jetty9.zip and CS320_Lab02.zip.
Open Eclipse, switch the Workspace to H:/cs320-spring2022 (on a lab PC) or C:/cs320-spring2022 (on your own PC).
Import CS320_Jetty9.zip.
Import CS320_Lab02.zip.
Expand the CS320_Lab02 project.
If it shows the JRE System Library either as JRE System Library[JavaSE-1.8] or jdk1.8.0_181 or later (up to 1.8.0_301), then you likely have no further steps to take.

Changing the JRE System Library

On the other hand, if the JRE System Library is shown as “unbound”, you will likely need to switch to a compatible library.

Go to C:/Program Files/Java and look for a JDK folder labelled jdk1.8.0_xxx. Hopefully, you have one of those installed in the Java folder. For the lab PCs, there could be multiple versions installed - choose the latest 1.8.0_xxx (this should be version 1.8.0_301). If a compatible version is present, then do the following:

Go into Eclipse, right-click on the CS320_Lab02 project.
Go to the the bottom, select Properties.
Select Java Build Path on the left.
Select the Libraries tab.
Select the JRE System Library entry.
Select the Edit… button on the right.
Select the Installed JREs… button on the right.
That will pop up a list of installed JRE’s.
If you see one for jdk1.8.0_181 (or later), select whichever one you want, and hit Apply, followed by OK.
You should now see that the Workspace default JRE has changed to the one you just selected.
Hit Finish, and then OK, and you are ready to roll. The JRE System Library for CS320_Lab02 should also have been updated.
If you do not see an acceptable JDK version, then select search, and browse to the C:/Program File/Java folder under Computer, and hit OK.
Now, all of the currently installed JDKs and JREs that are included in that folder will show up, and you can select an appropriate one. (Apply, OK, Finish, OK).
You should now be able to run the lab.

Installing a new JDK from Oracle

If you do not find an acceptable JDK installed on your computer, you’ll have to install one from this location:

Oracle Java SE 8 Downloads

Create a free Oracle account and then download and install the appropriate version for your Eclipse/java installation - the 64-bit version will show up in C:/Program Files/Java, and then you can select it as described above.

Scroll down to Java SE Development Kit 8u301.
Now select the appropriate file to download for your operating system. For Windows-64bit, that will be the Windows x64 Installer: jdk-8u301-windows-x64.exe.
Download the file - it is 169.5MB, it could take a few moments to download.
Run the executable - it will bring up the installer. By default, it will install to the C:/Program Files/Java folder. It will install both the JDK and the JRE at that location.
After it is installed, you can then follow the above instructions to set the JRE System Library to the JDK you just installed.

Other Issues

There are some other issues that have been popping up with CS320_Lab02.

For some unknown reason, the CS320_Lab02.zip file might be protected, and Eclipse won’t let you import it. Let me know if this continues to happen - I think this is fixed with the latest ZIP file. You may need to log all users off the lab PC you are working on before proceeding.
When you start Eclipse on the lab PCs, Windows might warn you about running a program that was downloaded from the Internet. You can ignore this and move on.
When you go to run main() in the CS320_Lab02 project, you mmight get a Windows Firewall warning. You can hit Cancel and the lab will work.