I'm not sure if this question has been answered in full or if my title is descriptive enough given my situation, but I've been asked to convert a project from being built with Ant to Maven. That part isn't too bad, but I've been told that this application was designed specifically for the JRE version 1.5 rather than the JRE 6 everything else I've been dealing with uses. Now, I'm incredibly new to Eclipse and Java themselves, so I was a bit confused when I was asked to tell either Eclipse or Maven to build this particular project using the JRE 1.5 instead. I have it installed, I believe, and I've tried to follow the steps outlined here: ( Eclipse: Build and conform to different JRE versions ), but I've run into a snag.
I've managed to change the Run Configuration to use the Alternate JRE jre1.5.0_11. When I then tried to build it, the console spat out the following:
[ERROR] Unable to locate the Javac Compiler in:
[ERROR] C:\Program Files (x86)\Java\jre1.5.0_11\..\lib\tools.jar
[ERROR] Please ensure you are using JDK 1.4 or above and
[ERROR] not a JRE (the com.sun.tools.javac.Main class is required).
[ERROR] In most cases you can change the location of your Java
[ERROR] installation by setting the JAVA_HOME environment variable.
I assume this means that I need to be using the JDK 1.5 in order to use the JRE 1.5, since I'm currently working with JDK 1.6. Now, is there a way to install the JDK 1.5 so that this project can use it? My JAVA_HOME variable currently points to the JDK 1.6, and I would like it to stay that way... Is there a way to be able to use both and simply tell the project (or Eclipse or Maven... however it works) to use a specific version of the JDK?
Yes, this is possible. You can install as many different versions of Java — JREs and JDKs — as you like, and tell Eclipse which one to use for each project.
First step is to install the JDK 1.5 on your machine (JDK is short for 'Java [SE] Development Kit', look for that on the Oracle download site). The JDK includes a JRE, so to make life easier you can usually just install the JDK and not worry about the JRE/JDK distinction.
Second step is to tell Eclipse about the new JDK. Go to Preferences... then Java > Installed JREs. Click the Search... button and Eclipse should find your newly installed JDK 1.5 and add it to the list.
Final step is to allocate that JDK 1.5 to your project. Bring up the Properties menu for your project (right-click it). Then set these values:
Java Compiler tab
Tick Enable project specific settings
Set Compiler Compliance level to 1.5
Java Build Path tab, Libraries subtab
Find the JRE System Library item, click Edit...
Set Alternate JRE to your newly installed JDK 1.5
It looks like you are using JRE 1.5 rather than JDK 1.5
Make sure you download the JDK 1.5 and your issue should go away. You can set the default JDK in the preferences, search for 'jre'.
Projects can also define their specific jre
Get JDK 1.5 from Here http://www.oracle.com/technetwork/java/javasebusiness/downloads/java-archive-downloads-javase5-419410.html
Related
I have two JRE in my system. One is 32-bit and the other one 64-bit. In Eclipse I can configure both and choose which one to use when running my application.
I'm wondering if I can do the same thing in Netbeans. I've tried to go to Project Properties, Libraries and then tried to configure a new JRE there, through Manage Platforms, but it doesn't accept the directory of my JRE. How should I proceed?
Be aware that I'm talking about JRE, and not JDK ;)
EDIT: I managed to make it work by downloading a new 32-bit JDK and selecting its directory. I still couldn't make it accept a JRE directory.
Whether or not you can run Netbeans with just the JRE depends on what bundle you have downloaded. In Netbeans 7 only C/C++ and PHP bundles can be run with the JRE.
Older versions of Netbeans include more languages under this JRE umbrella, but the principle is the same.
The JDK contains the JRE plus tools to debug and compile code, so if you're doing anything Java based apart from just running the IDE, netbeans depends on the JDK.
I am having two JRE / SDK in my development environment, however it was necessary in my situation to set JAVA_HOME to 1.4.2, this is causing my eclipse IDE to stop running as it required 1.6 and above.
May i know how i can modify eclipse ini or environment home to use my other 1.6 installation?
Please try the eclipse.ini entry above the varargs (the following two lines must be two lines in the eclipse.ini file)
-vm
C:\Java\JDK\1.5\bin\javaw.exe
Find the JVM
Right click the project in Package Explorer -> Configure Build Path
Add Library -> JRE System Library
Set JRE system library to JDK
Verify JDK is the reference library
From the menu in the top.. Proceed as follows--
Project-->Properties--> Java Build Path--> Libraries--> JRE System Library.
Now click Edit . Select Alternate JRE. Click Installed JRE. Provide path to your other JDK. Then FINISH.
That's it.
I have downloaded eclipse 3.1.2 to be able to make use of a particular library (Indus - http://indus.projects.cis.ksu.edu/). Under the 'Create a java project' dialog, the JDK section is automatically set to 1.4, which is fine. However, I don't have jdk 1.4 installed on my machine. Is it included with Eclipse 3.1.2? Also when I right click on the project and go to 'Properties' and select 'Java build Path', the jre is set to jre 6. Should this not be a jre suitable for java 1.4? Could someone also explain to me exactly what the jre is and how it ties in with the jdk?
Related question
You should be able to find older jdk's or jre's (like here). If you compile the Eclipse project for a certain version, newer jre's should be able to run them too.
I see JRE all over the place, but i can not be sure which JDK is compiling my code. How do i find out?
You can still check/set which JDK version you want to compile to. If you go to Window->Preferences, then click "Java" from the menu on the left and then "Compiler". The first setting allows you to see which JDK version is being complied with.
I know this doesn't directly answer your question since JDK isn't actually compiling it, but hopefully it helps!
Actually Eclipse has its own compiler. You can develop java apps using only the JRE and Eclipse
You don't find JDK explicitly mentioned anywhere because way to point to a JDK is under the name of 'Installed JRE'. That is Window > Preferences > Java > Installed JREs. This is useful when using m2e plugin.
secondly apart from having it's own built in compiler, it is recommended to you install one of your own to support development of Java programs. Except below from eclipse wiki page :
If you intend to use Eclipse for Java development, then you should install a JDK
I was trying to compile a Grails application referencing third party JARs on Mac OSX. Although my system's JRE and JDK is set to Java 1.6 I always got a Compilation error: java.lang.UnsupportedClassVersionError: Bad version number in .class file
when accessing classes in the JAR. Also when testing an existing Grails app the default stats of the app where showing that it's running with Java 1.6. So I really didn't have more ideas than to try to change the Java settings in Eclipse - I thought that's stupid as I'm not using Eclipse for the devlopment of this application - but voila - now the compilation of my app on the command line works just fine!
Can anyone explain me what Eclipse is doing here behind the scenes?
I've had set the JAVA_HOME manually before with no effect.
The JDK (JAVA_HOME) used to launched eclipse is not necessarily the one used to compiled your project.
To see what JRE YOU y can select for your project, check the preferences
General > Java Installed JRE
By default, if you have not added any JRE, the only one declared will be the one used to launched eclipse (which can be defined in your eclipse.ini).
You can add any other JRE you want, including one compatible with your project.
After that, you will need to check in your project properties (or in the general preferences) what JRE is used, with what compliance level: