Unable to run Java program in Eclipse Juno 4.2

Question

I reinstall my Eclipse environment every year when the new version is released. The most recent release - Juno - however, does not work as expected.

Currently, when I try running demos from Oracle, for example, it asks me to select an Ant file to run before compiling. After creating a blank Ant file to bypass the requirement (which I thought was rather dumb, since I don't think TDD is something that should be forced on people), it still refused to run, saying the "Selection could not be launched."

I understand that Juno is an update from the 3.x track to the 4.x track, but this seems a little ridiculous to me. What can or should I do so I can get Eclipse back up and running again?

Just to clarify:

All files in question are on my Eclipse workspace path
I don't do much in the way of Java development, though I know I'll need to do so soon. Hence, my unfamiliarity with the most recent version of Eclipse.
I would like to run my files & projects without Ant files. I know it has something to do with Run configs, but I don't know how to change them.

Please post what Oracle demo you are trying to run and the Ant file you created. — davidfmatheson, Aug 01 '12 at 17:35
I'm running FrameDemo.java and I just used a blank Ant file. However, I'd much rather just be able to run without an Ant file. — Edwin, Aug 01 '12 at 17:39
Which Juno did you download? Is it the same one as you dowloaded for Indigo? — nitind, Aug 01 '12 at 18:31

score 2 · Accepted Answer · answered Aug 01 '12 at 18:03

Here's what I did to run the demo from Eclipse Juno:

Downloaded the project from http://docs.oracle.com/javase/tutorial/uiswing/examples/zipfiles/components-FrameDemoProject.zip (if this is not the correct demo, then please provide the link you're using)
Unzipped it to my projects directory (not my workspace), so that you have:

PROJECTS_DIR/components-FrameDemoProject/src

PROJECTS_DIR/components-FrameDemoProject/nbproject

PROJECTS_DIR/components-FrameDemoProject/build.xml
From Eclipse, File > New > Java Project
List item Uncheck Use default location and navigate to <PROJECTS_DIR>/components-FrameDemoProject
Hit Finish
Drill down to src/components/FrameDemo.java
Right-click on FrameDemo.java and select Run As > Java Application

Let me know if any of these steps give you trouble.

Not sure why, but hovering over `Run As...` presented no options - at least none that I could click. It worked out after following your instructions, though, and Eclipse no longer gives me any issues when setting up a new project. Thanks! — Edwin, Aug 02 '12 at 17:47

score 0 · Answer 2 · answered Aug 01 '12 at 18:01

Take a look at you project properties and select the Builders entry. Do you see an Ant Builder entry? Try to select or create a Java Builder entry instead.

I just created a new Java Project in Juno and added the FrameDemo.java source. In my case, the Java Builder was selected as the default for this new project.

Unable to run Java program in Eclipse Juno 4.2

2 Answers2