I'm trying to compile a java program that is using JavaDB/Derby. On the command line I can run
java org.apache.derby.tools.sysinfo
without errors, but the following line in several of the files causes the error in my question title:
import org.apache.derby.client.am.SqlException;
causes
package org.apache.derby.client.am does not exist
I've done a fresh installation of JavaDB, but I don't think that matters. I've compiled this project once before, and I KNOW I didn't have JavaDB installed. I just had a directory at the top level of the project folder called lib with all of derby's .jar files inside. And I'm pretty sure I didn't have to set any environment variables either.
How can I fix this error? If I need to provide any more information, I will be happy to do so.
I'm using Windows 7 and jdk1.7
Sounds like you have an issue with the JavaDB JARs not being on your classpath. Make sure you specify them using -cp or -classpath on your javac command.
Related
I´ve made a Java Project on Windows and now I want to use it under Linux.
Since I am working with Files, I "need" the org.apache.commons.io.FilenameUtils package. Under Windows I am working with IntelliJ, so it manages everything for me. I am sharing the Directory of the Project via VirtualBox shared folder. When I try to compile the Main class I get
error: package org.apache.commons.io does not exist
import org.apache.commons.io.FilenameUtils;
^
I already tried javac -classpath . Main.java but I just get the same Error.
To be honest I am completely lost from this Point on, althought I already googled the Problem for a bit. I run Debian and Java JDK 8
You need to have the Commons IO Jar in the classpath when compiling, for example:
javac -cp .:path_to_commons_io_jar Main.java
When I run javac on an ubuntu linux system I get a "package does not exist" error from the line
import org.voltdb.ProcInfo
From the answer below, I know that I need to add packages from "org/voltdb/ProcInfo" to my javac class path to resolve this error.
Java Package Does Not Exist Error
But when I search for the system for such a directory structure I don't find it.
prompt$cd /
prompt$sudo find / -type d -path 'org/voltdb/ProcInfo' //returns no output
I downloaded VoltDB community edition 3.5 and am trying to compile and run a voltdb project. It seems unlike that Volt's .tar does not include the necessary java libraries -- but that seems to be what is going on. Am I understanding what is happening correctly or am I missing something? I have only working knowledge of Java and Linux.
You need to add the VoltDB .jar file to the classpath
first off let me start by saying I am completely new to Java, but to give you an idea of how new; I started reading lots of books, examples and so forth and began programming Java using Eclipse about 2 months ago. However, I found a really cool bit of advise about using notepad and the terminal to program instead. Kinda crazy for a newbie to go the hard route, but I love a challenge and I'm serious about learning.
So, In Eclipse I had a really good grasp of how to import, add jars compile etc. When I started using pico and using the terminal (I'm running ubuntu) to compile all went really well, until I wanted to use packages. I've spent two days pulling my hair out because no matter what I do I can't figure it out.
I'm trying to use the acm.jar (which I have many times in Eclipse) however I'm completely lost on how to use it when compiling from the javac in terminal.
So what I'm asking for, is for someone to explain the process getting my jar file to work.
All I'm using to create my java programs is the pico (or notepad) and the javac in the terminal.
To compile and run a java class using external libraries, you have to add that library to the classpath. The classpath is the set of places where the java compiler and the JVM look to find any external libraries/classes that it needs during the process of compiling/executing.
Setting the classpath can be done in 2 ways:
Set an environment variable called CLASSPATH
Set it when your run javac/java
Setting the classpath when running javac/java is done like this:
javac -cp path/to/jar1:path/to/jar2:path/to/jar3:path/to/dirContainingClasses
yourMainClass.java
To run:
java -cp path/to/jar1:path/to/jar2:path/to/jar3:path/to/dirContainingClasses
yourMainClass
: is used as a separator on Linux, for windows use ;
Assuming your source files are in src. Assuming you want your compiled classes to be in classes. Assuming your source files reference classes that are in lib/acm.jar:
javac -cp classes:lib/acm.jar -d classes src/com/foo/bar/MyClass.java
will compile the class com.foo.bar.MyClass and put the generated MyClass.class file in classes/com/foo/bar.
You need the acm.jar file in the classpath. That's what the -cp lib/acm.jar option does. You also need classes in the classpath, because MyClass probably references other classes that you have already compiled and that are in your classes directory.
To run your class, it has to be in the classpath, and acm.jar as well:
java -cp classes:lib/acm.jar com.foo.bar.MyClass
As you see, the classpath contains jar files, and directories containing the folder hierarchy which matches the package hierarchy.
I wouldn't use javac from the command line directly, though. Try using a real build tool, that will build all your classes at once, like Gradle or Ant. Maven is also very popular, but I hate it with passion.
This question already has answers here:
What is a classpath and how do I set it?
(10 answers)
Closed last year.
I am trying to compile a library I wrote, using javac and I am getting the error: package org.json does not exist. My program includes org.json.JSONArray and org.json.JSONException.
I have this package installed on my computer because I have successfully compiled android apps that import org.json libraries. I'm pretty sure all I have to do is specify a -classpath but I have been unable to find where these files live on my system (ubuntu 10.10 64-bit sun-java6).
Having been unable to find these on my own system I downloaded the org.json files from here, but I was unable to compile them individually because they were co-dependent on each other.
So I have a couple questions:
Does anyone know where the org.json
package lives from android sdk
install?
Where might I find a tutorial
explaining these basic concepts
regarding compiling, and javac.
Whatever external jars you need to compile with should be on the classpath when you compile. The most non-invasive way to do this is do add these items to the javac command line such as
javac -classpath /path/to/json.jar;. -g YourClass.java
or more likely if you use an IDE, add these jars to your referenced jars of the project in your IDE.
It usually isn't a good idea to pollute the global $CLASSPATH variable, as this then gets pulled in for everything you do with java, which may cause unintended conflicts.
Wherever you like. What you need to do is examine your CLASSPATH variable, and make sure it includes the directory with your library.
Here's the first thing:
$ echo $CLASSPATH
and you'll see your classpath as it is.
Now you need to find the jar file containing the org.json; consult the documentation, but it may be something as simple as json.jar. On most LINUX systems you can then just run
$ locate json.jar
And you'll get a path name for the jarfile. Make sure that path is part of your CLASSPATH and you'll be in fat city.
Oh, and the "Getting started" tutorials at Sun Oracle are the easiest place to start.
Actually, having looked at the files, they may not be packaged as a jar file. In that case, you want to put them into your sources starting at some top directory (src in this example.)
/src
/org/json/ ... put the json files here
... put your files here
and when you compile, they'll all be included, which will resolve all the dependencies.
Again, the place to look for first steps is that tutorial.
use "java" command instead of "javac"
I'm running snow leopard and I just wrote a Java class on eclipse. The eclipse project references a user library which itself points to a bunch of jar files I've got somewhere in the system. When I run the app through eclipse, everything goes smoothly.
Then I export the class as a jar file and try to run it form the terminal by typing:
java - jar myApp.jar
It throws a java.lang.NoClassDefFoundError exception, meaning that it can't find the libraries I try to reference.
Knowing that my user library jar files are in /Users/myname/tempJars, I also tried to either mention the classpath using the -cp option
(java -cp /Users/myname/tempJars -jar myApp.jar) or to directly reference it in the manifest file. Both attempts failed and the error is the same.
These libraries are Java 1.5 libraries, so I thought I should try and reference another java version by mean of the JAVA_HOME environment variable. I built the following script:
export JAVA_HOME=/System/Library/Frameworks/JavaVM.framework/Versions/1.5/Home
export PATH=$JAVA_HOME/bin:$PATH
export CLASSPATH=$CLASSPATH:/Users/myname/tempJars
java -jar myApp.jar
Again, no good. I googled how to execute jars in snow leopard, found the 32/64 bit big deal in some places and even tried executing with the -d32 option, but still to no avail.
Since the same code executes just fine in eclipse, I'm pretty convinced it's just a matter of setting up the JVM so that it includes the user libraries correctly.
Could anyone help me with this?
Thanks in advance.
You need to list the JARs themselves out on the classpath, not just the directory containing them. (Listing the directory is for when you have unarchived .class files in the package hierarchy lying around)
You will probably need to do -cp /Users/myname/tempJars/libA.jar:/.../libB.jar
I believe some (but potentially not all) JVMs support wildcards so -cp /Users/myname/tempJars/* or some variant thereof may work.