Java - Different behaviour between exported JAR and Eclipse IDE - java

today I got a strange problem while trying to call a batch file from Eclipse IDE.
The setting for a normal user is:
Call a .bat file
This sets some environment variables
And calls a Eclipse RCP application
The setting for my program is:
Call the same .bat file via Runtime.exec()
When calling it as normal user, all works well, the RCP gets started.
When calling it within Eclipse IDE via Runtime.exec() I get an error message complaining that Program Files\jre6\bin\server\jvm.dll could not be found (although it is there).
When exporting my program as an executable .jar file, it works well like I would click on the .bat myself.
What is the difference? (Operating system is Win7)

In Eclipse,
Right click on the project and click "Properties".
Select "Java Build Path".
Select "Libraries" tab.
Select "JRE System Library" and click "Edit".
Check if the System Library points to a valid JDK installation(not JRE). If it doesn't point to a valid JDK installation.
Select "Alternate JRE" and click on "Installed JREs"
Click on Add, point to valid JDK installation and click OK.
In "Alternate JRE" drop down, select the newly added valid JDK and click Finish.
Run the program and check.

Ok got it.
It seems to be a specific problem of Eclipse 3.7.
After installing 4.2 all works perfectly well.

Related

I tried to run Java in Eclipse and it asks me to select ant build and either one I choose it says unable to find ant file to run...

So I just installed JRE, JDK and Eclipse and I was trying to run this famous HelloWorld code, but it shows this message as in attached images. What's the ant build?
Thanks!
dont run it as ant, right click on your file in eclipse select run as then choose java application
It looks like you don't have your file in your buildpath (what eclipse uses to figure out what files it should compile). Right click on the folder and select Buildpath -> Use as Source folder. Now when you hit run it should hopefully work.
Go to Run
Run Configurations
Select Java Application(From Left Pane)
Fill Up Your Project Name and your Main Class
Apply and Run
example image
Best way is to
Delete all eclipse files in your pc and again download eclipse and install it. Definitely works
Click Run As > Java.
If Java is not available there, click Run Configurations > JRE.
Choose "Execution environment" , click Environments and choose the Java version you want to use. Click Apply, Run.
That should do it.
Try to create a Java class file with suitable name and method.This error usually occurs when compiler doesn't understand which file to execute.
Simply click the javadoc next to your console and run it

Eclipse EE IDE Gives Errors in code yet still runs

So I just installed Eclipse on my computer, which I just got a new hard drive for, and I have this weird problem. I installed the JDK, and eclipse, and got it up running and looked at my screen. The first thing I saw was like a million errors that weren't there on my other computer. But when I ran the code, it still works perfectly fine.
Here is a picture
Right-click on your project folder "Build Path" -> "Configure Build Path" then choose tab "Libraries". Ensure your JRE System Library is set correctly. If set, you can double click on it and check it's configuration if not, press "Add Library" choose "JRE System Library" and proceed accordingly.

Ant - Eclipse [Reference to undefined variable INSTALLED_PATH]

I cannot run ant files in eclipse, when i try to run them the following dialog appears.
SOLVED: I am not sure what was the problem, but I think the java/ant path in windows path variable was the problem.
However I have removed any extra value from windows path variable; restart the computer and now every thing works fine.
Referred from : Eclipse 3.7, Ant, Java 1.7
In Eclipse, click the ant file -- Run As -- External Tools Configuration and click on the JRE tab.
Select "Run in the same JRE as the workspace"
I think The problem is because of:
You are using INSTALLED_PATH variable in your ant script which is not undefined.
specify value for INSTALLED_PATH in the below screen
Right click on ant file, then choose Run AS-> Ant build(2 Option), then select environment tab in the pop up, then add a new variable "INSTALLED_PATH"

Java Debugging with Eclipse

I'm trying to debug a program that calls a function in the HashSet class, but I get a message saying: Source not found. I know this is something with not finding the library files. Please, can someone guide me to how I can set it up? Which library files should it be pointing to?
Thank you very much for any pointers.
Finally got around to doing this awhile ago and I love it.
First you need to download the Java source. I got mine here (look for "Java SE 6 JDK Source Code"): http://www.oracle.com/technetwork/java/javase/downloads/index.html. Download that and stick it somewhere on disk that you can find easily. Keep in mind that the JAR you download has to actually be "installed" somewhere via you agreeing to a license agree (extract it with jav xvf jarname.jar and check the README it contains).
For any JAR file on your CLASSPATH in Eclipse, you can add a source attachment to it to point to its source code. The easiest thing to do is bring up the Package Explorer view. Underneath your project, you should see an item for your Java Runtime Environment (JRE) (mine is called "JRE System Library [JavaSE-1.6]"). Click on the expansion arrow for that and you'll see a list of JARs.
Most all of the Java classes you'll care about viewing are stored in "classes.jar". Right-click on that JAR and select "Properties". In the left hand menu, select "Java Source Attachment". On the right side, click "External Folder" and find the source code that you downloaded and installed and put that folder into the "Location path" field. Hit "Apply" and "OK".
Now you should be able to right click on any built-in Java class in your code and use the "Open Declaration" command or when debugging you will now step into the Java source.
It's a great capability to have. Enjoy!
HashSet is in JRE Package, so you can download JDK source and attach it into eclipse.
An other way, when you can not find out the source package, you can use JD-Decompiler
which has eclipse plugin to decompile your class, it work and show most like original source file.
Choosing a JDK instead of JRE for the runtime environment worked for me!
NOTE:Make sure you have a JDK installed and not only JRE before proceeding.
Remove the current system JRE library:
Right Click project -> properties -> Libraries -> Remove current JRE Library.
Add other installed library to your project:
In the current dialogue box, click "add library". by default JRE system library is selected, if not, select it and click next. now select "Alternate JRE" and click "Installed JRE". In the new dialogue box, click search and provide the path to your installed Java environments.
Finalize
Select an installed JDK, and click OK. Click FINISH and again OK to proceed.
Abdul,
The best way is as the others explained to download the sources and attach them in the eclipse.
The EASIEST way would be installing the java decompiler (JAD). Take a look at http://jadclipse.sourceforge.net/install.html. Its explained there in 4 super simple steps :)

How Do You Install the source for the java libraries in Eclipse?

How do you install the source for the java libraries in Eclipse?
This happens automatically if you set up a JDK rather than a JRE.
Normally, when you start eclipse, it sets up the JRE that was used to start eclipse. You'll usually want to override this with a JDK so you get the source. To do this:
First, make sure you have a JDK installed (and not just a JRE)
Start eclipse
Go to Window->Preferences->Java->Installed JREs
Press Add...
Choose "Standard VM" and press "Next..."
Press "Directory...", select the JDK installation directory and press "Ok"
Press "Finish"
Make sure you check the box next to the new JDK
Press "Ok" to finish up
This will set up the source properly for you.
You can do it in the project preferences, but I find quite faster just to ctr+click over a object or class defined in the standard library and then "attach source" in the page that will gently inform you that there are no sources attached.
You then can point to the "src.zip" in your JDK distribution.
The way that I do it:
Prerequisite: you have the source downloaded. It comes with the JDK. (src.zip)
Open up a Java file
Ctrl + Click on a class name.
Click on the button that says 'Attach Source'
Locate the src.zip file. (Usually in the JDK install location)
Now you have the source installed!
WHat do you mean with java source? The java.lang package? Because there shouldn't be a need to "install" them. Creating a new Java Project ( any kind of Java Project) should be enough. Could you describe your problem in more detail?

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