need java help again - collections

Firestorm ZERO · Post by **Firestorm ZERO** » Sun Jul 23, 2006 3:22 pm

Ok. I making a GUI application this time. All it does is handle some data so I decided to use a LinkedList.

I imported java.util.*;

I had the following...
LinkedList stack = new LinkedList();

ok no prob. But when compiling it warns about unsafe operations but still works fine if ignore it.

So to fix that warning I did this...

LinkedList<String> stack = new LinkedList<String>();

but now it won't even recognize it.
In eclipse for "LinkedList" it says "The type LinkedList is not generic; it cannot be parameterized with arguments <String>" and for "<String>" it says "Syntax error, parameterized types are only available if source level is 5.0" and so can't compile. It gives "Exception in thread "main" java.lang.NoClassDefFoundError: Assign3"

Can anyone help me out on this.

A_old · Post by **A_old** » Sun Jul 23, 2006 4:08 pm

do you have eclipse set to compile ur project using jdk 5.0 or the 1.4 settings?
that's the first thing to check. Also, it isn't a big deal to have a warning using the first method, it just means you have to cast from object to your type as you use the data.

Firestorm ZERO · Post by **Firestorm ZERO** » Sun Jul 23, 2006 11:46 pm

Ok. I'll check it the settings when I get a chance.

While yes it is just a warning, but it is better programming practice to remove warnings if possible.

A_old · Post by **A_old** » Mon Jul 24, 2006 7:03 am

some are worse is the point. i guess it depends on what the application is being written for. if it's for school or work, get rid of them. if it's for your own personal use, it doesn't matter. another thing is that wasn't a warning in 1.4.x -- they just added that w/ the 5.0 jdk, so if you're writing 1.4 code, it really shouldn't be showing up..if you're using 5.x functionality (enums, the new string stuff, etc), then that's a different story

Firestorm ZERO · Post by **Firestorm ZERO** » Tue Jul 25, 2006 6:09 pm

I just checked it is using jre1.5.0_06. There are no alternative JRE installed.

This is for school work so I would like to try to get this warning fixed.

All I am using is the LinkedList to add and remove nodes. The rest is just GUI stuff like buttons, textfields and scrollbar and such.

A_old · Post by **A_old** » Tue Jul 25, 2006 8:28 pm

I understand that, but you can set eclipse to enforce functionality based on Java versions.

Right click your project, go to Properties, Click on Java Compiler, now look under JDK Compliance. Make sure it's set to 5.0. Now try parameterizing the type of the LinkedList.

LinkedList<String> li = new LinkedList<String>();

Compiles just fine for me w/ out warnings w/ the Compliance level set to 5.0. I hope this helps.

Firestorm ZERO · Post by **Firestorm ZERO** » Wed Jul 26, 2006 9:00 pm

Thanks again Amro. That fixed it

A_old · Post by **A_old** » Wed Jul 26, 2006 11:20 pm

No problem bud