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Beginning Java

import java.util.Scanner issues

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posted 19 years ago

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Hello all, officially my second out of what I promise to be many posts.

I've been searching around online for other Java tutorials (now have a few good ones plus the Head First Java book) and came across java.util.Scanner in a practical exercise.

If I compile the code in an ide (which I know everyone hates for beginners) it compiles fine.

If I compile from the command line, using javac LoopingLock.java, I get compile errors stating..

LoopLock.java:1: cannot resolve symbol
symbol: class Scanner
location: package util
import java.util.Scanner;
^

And other various compile errors complaining about me trying to use Scanner.

Here is a bit of the code from my java file.

I'm not so sure it's an error in my code so much as perhaps an error in my system variables somewhere? But if that's the case, wouldn't the commands javac and java also not be working?

Any help would be appreciated so I can learn from the command line before going ezmode with Eclipse or Netbeans.

Thanks,

Nate

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marc weber

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posted 19 years ago

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Originally posted by Nathan Leniz:
... I'm not so sure it's an error in my code so much as perhaps an error in my system variables somewhere? But if that's the case, wouldn't the commands javac and java also not be working? ...

Scanner was introduced with Java 1.5, so my guess is that your system PATH is pointing to a prior version (so the commands work, but not with new features).

You can type "javac -version" (without the quotes) to check the compiler version. You'll get a lengthy error message for not specifying a source file, but the version should display first...

What operating system are you running?
[ December 04, 2006: Message edited by: marc weber ]

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Nathan Leniz

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posted 19 years ago

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javac -version wasn't a valid command

I tried java -version and it printed this to the screen...

java version "1.5.0_09"

Followed by other information about Java.

Still just as stumped. I hate being a noob. I appreciate the fast reply.

Oh, Windows XP home.

Nate

[ December 04, 2006: Message edited by: Nathan Leniz ]
[ December 04, 2006: Message edited by: Nathan Leniz ]

Keith Lynn

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posted 19 years ago

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Since javac -version doesn't work, that means you're Java compiler is not 1.5.

marc weber

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posted 19 years ago

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Originally posted by Keith Lynn:
Since javac -version doesn't work, that means you're Java compiler is not 1.5.

Right, the "-version" flag for javac was added with 1.5. And yet the java version seems okay, and these tools should both be in the same directory.

What does your system PATH look like?

Also, if you have a system CLASSPATH set, what does that look like?

(For Windows XP, I think these are under Start > Settings > Control Panel > System > Advanced > Environment Variables.)

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Henry Wong

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posted 19 years ago

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For eariler versions of the Java compiler, also try...

javac -J-version

Henry

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Keith Lynn

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posted 19 years ago

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I think it's possible that an updated JRE was placed on the machine when the OP installed a browser, but possibly the only JDK is 1.4 or 1.3.

Nathan Leniz

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javac -J-version shows java version "1.4.2_13"

my path is set to c:\j2sdk1.4.2_13\bin

and classpath is set to the same. One of my friends (who I can't get on googletalk atm) helped me set it up initially and told me to make them both the same, so perhaps it could have been bad advice?

Nathan

Keith Lynn

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posted 19 years ago

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The version of the JDK didn't include Scanner.

Did you ever download 1.5?

Nathan Leniz

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posted 19 years ago

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I thought I did, but perhaps I didn't. I'm downloading again.

Thanks for all the replies. I'll have to show my wife this thread, perhaps she'll cave and let me go on the Cattle Drive.

Nate

Nathan Leniz

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posted 19 years ago

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Upon further investigation, I found out the Java I thought I was installing but not seeing was going into a nice little folder in my Program Files. javac version is now 1.5.0_10 along with the java version.

I R dumb. Feel free to beat me. Thanks again everyone for your help.

Nathan

marc weber

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posted 19 years ago

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So the code compiles now, right?

I would also suggest removing the system CLASSPATH entirely. Until you get comfortable with how this works, it's likely to cause problems (especially since it probably does not include the current directory ".").

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Nathan Leniz

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posted 19 years ago

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It does compile, yes.

And it runs.

And it took me a minute or two to figure out why I had to keep going
set CLASSPATH =

Then it finally dawned on me that I have to add every directory I plan on storing stuff in, so I went back and changed the classpath variable to include the real Java 1.5, as well as my projects folder.

my variables now look like

path = C:\Program Files\Java\jdk1.5.0_10\bin
classpath = C:\Program Files\java\jdk1.5.0_10\bin;C:\projects

Actually crashing through it full bore, reading the stuff here and reading the documentation from Sun helped me out quite a bit. I just wish they would have explained it in plain english, like "Make the variable name Classpath, then in the variable value type out the true path to your Java directory, put a semi-colon there, then type out the true path to whatever other directories you plan on storing your *.java and *.class files in"

Maybe not truly the right way, but it works. And yeah, it probably does say that, but us military folk ain't big on reading and ejukayshun.

Again, thanks for all the help. I'm sure more questions will follow.

Cheers,

Nate

marc weber

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posted 19 years ago

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I would still recommend that you remove the CLASSPATH variable entirely. With earlier versions of Java, you needed to set this; but now Java is "smart" enough to find the basics without it, and having this set will likely cause problems later. If you do keep it, then at least add a dot (".") to indicate the current directory...

classpath = .;C:\Program Files\java\jdk1.5.0_10\bin;C:\projects

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Nathan Leniz

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posted 19 years ago

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I'll heed the advice of those who know more than me. I've removed the classpath variable entirely and everything still works.

Ah, to make up for all these shenanigans, I shared (what I think is) a very funny story in the drivel and nonsense forum.

Again, thanks much.

Nate

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