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| Re: Students run Java 8. I need Java 8 to make applications. What Eclipse IDE is best? [message #1806188 is a reply to message #1806180] |
Sun, 05 May 2019 14:45   |
 David Wegener
Messages: 1445
Registered: July 2009 |
Senior Member |
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Some additional information regarding the difference between a JDK and a JRE. A JDK includes tools to build and run java programs. A JRE only includes the tools to run java programs. Essentially, a JDK contains all of the features included in a JRE. In addition, it provides a compiler, debugger and other monitoring/profiling tools. Put another way, a JRE is a subset of a JDK without the development tools. The JRE is the minimal set of features necessary to run Java programs. If all you have installed on your PC is a JRE you can run java programs but can't build or debug them. The smaller JRE reduces the footprint necessary to run Java programs. Initially, the Sun license (eventually bought by Oracle) for the JDK allowed you to redistribute a JRE with you program. Oracle has apparently stopped providing a separate JRE with Java 11 and later. However, they appear to have included tools in the JDK to allow developers to create their own JRE.
If you interest is in developing Java applications or teaching Java development, then you will likely want to install the JDK. You would only need to worry about a JRE if you planned to distribute your applications to computers that weren't being used a development machines.
Eclipse requires a Java VM in order to run. At a minimum that means a JRE, but since the JDK includes the Java VM, you can run Eclipse on a JDK. In fact the preferred method for Java development is to run Eclipse on a JDK. One of the extra features provided by a JDK is the full source code for the Java runtime libraries. Having this available when developing Java applications is a great help. When you run Eclipse on a JDK with source installed, it will automatically find the source for source lookups.
The Eclipse Java preferences refer to JREs and this may cause some confusion. The configured Java installations on the JRE preference page can point to both JDKs and JREs.
My recommended setup for Java development would be to install a JDK and launch Eclipse using the JDK. Make sure that the Installed JREs has an entry for the JDK you want to develop against.
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| Re: Students run Java 8. I need Java 8 to make applications. What Eclipse IDE is best? [message #1806231 is a reply to message #1806188] |
Mon, 06 May 2019 15:35 |
Patrick Moran
Messages: 141
Registered: March 2018 |
Senior Member |
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Thanks for the information.
I think the idea to use the IDE is what I need at this point. The only thing is that I installed it and have had problems with the while I used to be able to make JARs that would open and operate properly on my Mac but not on my HP, the same code used with the IDE now will not even open and operate properly on my Mac. The software, opened/operated from Eclipse works fine, but the JARs fail. Part of the problem seems to be that the combination of JRE included with the IDE and the software in the JAR itself (somewhere in there I think) can no longer identify the subdirectory where the JAR is, and that means that it loses the ability to do things like access the sqLite DBs located in the same subdirectory.
I am now trying to get the IDE off my system and reinstall the previous setup in the hope that I can at least restore the ability to make JARs that can be sent to others who also have Macs.
It may be that I cannot operate from the IDE and the old setup on the same computer at the same time because they will perhaps share access to stores of information regarding various settings. I'm not sure of that. I just know that I have to start over and take better notes this time.
[Updated on: Mon, 06 May 2019 15:38] Report message to a moderator |
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