Today, I'm going to share a problem which I think it's quite common:
- importing Java Maven projects into Eclipse and expecting Eclipse to just work with it.
You do:
1) sync from source control
2) import existing maven projects to eclipse
3) see many red errors in Eclipse.
4) yeah , I forgot to set the Maven settings file
5) still some projects are failing
6) try to fix each problem 1 by 1
Why does it happen like that?
Most common is that it will set a Java Compiler version which is from the POM.xml but then the JRE environment specified could be... just not right. So your POM.xml says "compiler version 1.7", but the Maven projects you import are automatically assigned Java1.5...
So errors like
- You cannot use @Override here
or for java1.7
- new ArrayList<> constructor not found (or not valid expression).
So you have to go to each project, reconfigure build path parameters to point to JRE1.7 manually, even though you have specified JDK1.7 as installed JDK.
Imagine fixing this manually for 20-50 projects (you've just been moved to moderately progressed project)
Even if you explicitly set the Maven settings in the Preferences menu, you would not solve your problem.
The single solution is to:
1) delete all projects (
only
from Eclipse )
2) reimport them, because NOW you have set the Maven settings BEFORE the importing...
Just crazy... not being able to automatically adapt the projects to the new maven settings file... not even "clean" and "maven update" help...
Best wishes,
Leni Kirilov
Showing posts with label compiler. Show all posts
Showing posts with label compiler. Show all posts
Friday, June 07, 2013
Monday, May 24, 2010
JDK 1.6 installation problems
Today's topic is Java Developers' Kit.
I've had a peculiar problem with JDKs. I wanted to install the latest version of JDK 1.6 update 18 at the time, but I also wanted to have JDK 1.5 so that I test my application with different compilers and runtime environments.
However there was some sort of problem with it (the source of it, I am unaware till this day) that caused my Windows unable to detect my successful installation. I checked that on this special site java.com
I could also check it with an applet in a page - it said that I need to install java...
1. First idea - reinstall
I thought that my register was messed-up and ran CCleaner to clean it. That didn't help.
I decided to reinstall it and here's my first surprise:
After the successful uninstall and running CCleaner again (just to be sure), and decided to reinstall the JDK
I've got a very "funny" error message (something like this - I don't remember the correct caption):
"Installer has detected that you have JDK installed. Do you want to repair/reinstall it?"
If you click NO - the installer shuts down.
If you click YES - the following message appears:
"You don't have JDK installed on your machine!"
Holly shit ! Isn't that just a bit contradicting...
Obviously, the algorithm at the beginning isn't the same as the one at the end...
2. Second idea - install older version
OK. I cannot override this incorrect installation. So let's try to downgrade it a bit.
I decided to try JDK 1.6 update 17. When I run it it said:
"You have already installed a higher version of JDK" - installation finished!
Thank you very much, smart installer!
3. Third idea - ask Google
"OK stop trying to be a smart ass. There has to be somebody with the same problem that has a solution!"
was my thought.
Yeah, right... After many hours of searching and "smart solutions", none of them helped me.
I intend not to list them here... just too many and very customized...
One of them seemed promising to me.
Google helped me find a tool and step-by-step solution.
4. Forth idea - clean up registry
I absolutely had no other choice than to try and clean my registry.
Including backing up my registry and using a free tool called "JavaRA" that could help me maintain my system and Java versions and updates very well... well I tried it and it didn't help... I was very disappointed but maybe my expectations were just too great.
5. No idea - desperation
I was quite desperate that my JDK ws not correctly installed. My applets weren't working. Eclipse stopped working at a certain moment. NetBeans - too. I even had to use system restore... a total disaster.
And I just migrated to Windows 7 Pro 64bit version... which seemed nice for user but apparently not for JAVA users... Using Win XP I didn't have such problems (although I think I had a similar problem a few years ago).
...
but I had a workaround!!
6. The workaround - JDK 1.7 unofficial!
Well, I was lucky I accidentally installed JDK1.7 which is still unofficial and doesn't overwrite the latest JDK 1.6. So when I installed and played around with PATH and JAVA_HOME variables and Eclipse and NetBeans configurations, I was able to continue with my Java project development.
But I was still unsatisfied, because this is just a workaround !
I've had a peculiar problem with JDKs. I wanted to install the latest version of JDK 1.6 update 18 at the time, but I also wanted to have JDK 1.5 so that I test my application with different compilers and runtime environments.
However there was some sort of problem with it (the source of it, I am unaware till this day) that caused my Windows unable to detect my successful installation. I checked that on this special site java.com
I could also check it with an applet in a page - it said that I need to install java...
1. First idea - reinstall
I thought that my register was messed-up and ran CCleaner to clean it. That didn't help.
I decided to reinstall it and here's my first surprise:
After the successful uninstall and running CCleaner again (just to be sure), and decided to reinstall the JDK
I've got a very "funny" error message (something like this - I don't remember the correct caption):
"Installer has detected that you have JDK installed. Do you want to repair/reinstall it?"
If you click NO - the installer shuts down.
If you click YES - the following message appears:
"You don't have JDK installed on your machine!"
Holly shit ! Isn't that just a bit contradicting...
Obviously, the algorithm at the beginning isn't the same as the one at the end...
2. Second idea - install older version
OK. I cannot override this incorrect installation. So let's try to downgrade it a bit.
I decided to try JDK 1.6 update 17. When I run it it said:
"You have already installed a higher version of JDK" - installation finished!
Thank you very much, smart installer!
3. Third idea - ask Google
"OK stop trying to be a smart ass. There has to be somebody with the same problem that has a solution!"
was my thought.
Yeah, right... After many hours of searching and "smart solutions", none of them helped me.
I intend not to list them here... just too many and very customized...
One of them seemed promising to me.
Google helped me find a tool and step-by-step solution.
4. Forth idea - clean up registry
I absolutely had no other choice than to try and clean my registry.
Including backing up my registry and using a free tool called "JavaRA" that could help me maintain my system and Java versions and updates very well... well I tried it and it didn't help... I was very disappointed but maybe my expectations were just too great.
5. No idea - desperation
I was quite desperate that my JDK ws not correctly installed. My applets weren't working. Eclipse stopped working at a certain moment. NetBeans - too. I even had to use system restore... a total disaster.
And I just migrated to Windows 7 Pro 64bit version... which seemed nice for user but apparently not for JAVA users... Using Win XP I didn't have such problems (although I think I had a similar problem a few years ago).
...
but I had a workaround!!
6. The workaround - JDK 1.7 unofficial!
Well, I was lucky I accidentally installed JDK1.7 which is still unofficial and doesn't overwrite the latest JDK 1.6. So when I installed and played around with PATH and JAVA_HOME variables and Eclipse and NetBeans configurations, I was able to continue with my Java project development.
But I was still unsatisfied, because this is just a workaround !
A developer must never be satisfied with a mere workaround!
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