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Import javax.vecmath
(6 answers)
Closed 1 year ago.
Preamble: So this all started with just trying to use javax.vecmath.Vector2d. I didn't have javax.vecmath so I spent a bit of time trying to get it, found that I needed to download Java3D.
After a long time of trying to download Java3D for Java (version 16.0.2), I eventually got it together with the vecmath.jar file landing in /Library/Java/JavaVirtualMachines/jdk-16.0.2.jdk/Contents/Home/lib/ext. This got rid of the error: package javax.vecmath does not exist error message.
Then, I got the message
<JAVA_HOME>/lib/ext exists, extensions mechanism no longer supported; Use -classpath instead.
.Error: Could not create the Java Virtual Machine.
this also wasn't letting me use any java commands in shell.
A bit of research and I concluded the solution to be moving (via Finder select and drag) j3dutils.jar, vecmath.jar, and j3dcore.jar over to lib and just deleting the lib/ext directory. I have gotten rid of the <JAVA_HOME>/lib/ext exists problem but back to error: package javax.vecmath does not exist.
I don't even know what to do know. I just want to use javax.vecmath. Am I going about this the totally wrong way? How can I get this to work?
Okay, I figured it out.
How to use javax.vecmath in Mac OS(11.5.1) with Java(16.0.2)
I am giving a description that sort of includes why I do things, skip to the TLDR at the bottom if you just want an answer.
Step 1: Download the latest version of Java3D
This contains vecmath, along with j3dcore and j3dutils. It will download a .zip file. Unzip the file and it will expand into a new directory with another .zip file inside, j3d-jre.zip. Unzip j3d-jre.zip and it will expand into a directory lib. Inside lib will be a subdirectory, ext, with three .jar files inside: j3dcore.jar, j3dutils.jar, and vecmath.jar. You can put these literally anywhere, just make sure you keep track of their location (I put them in ~/Library/Java/Extensions, this location is on the hard drive and will need an admin password to do anything–use
sudo unzip /path/to/j3d-jre.zip
if you are doing things in shell). You CAN put the ext directory in JAVA_HOME/lib/ but after Java 6, this will cause a problem.
Step 2: Change CLASSPATH
Java has no idea how to find vecmath.jar so you have to specify it.
Option 1: Specify CLASSPATH with every shell command
The simplest version is using
javac -cp ".:/path/to/vecmath.jar:" MyMainProgram.java
to compile and
java -cp ".:/path/to/vecmath.jar:" MyMainProgram
to run the program (you can also replace -cp with -classpath and it will do the same thing)
This option won't ever destroy your CLASSPATH but you also have to include the -cp command every time you compile and run a program that imports javax.vecmath.
Option 2: Specify CLASSPATH with every new terminal window
A little more lasting than -cp, you can define CLASSPATH such that any changes will only take place in that terminal window. Use this form:
export CLASSPATH=".:/path/to/vecmath.jar:"
Now when you call
javac MyMainProgram.java
java MyMainProgram
Java will see that CLASSPATH is .:/path/to/vecmath.jar and everything will compile and run without adding the -cp command.
The main downside of this option is that if you update CLASSPATH again, you have to remember to add the previous CLASSPATH (which you can see at any time with echo $CLASSPATH)
Option 3: Permanently add CLASSPATH to terminal
Enter the following into terminal:
open ~/.bash_profile
this will open a window that may or may not have code in it. Regardless of any pre-existing code, scroll to the bottom and add
export CLASSPATH=".:/path/to/vecmath.jar:"
This option holds the CLASSPATH in all terminal windows forever or until you change it (using any method above).
TLDR
Download Java3D for macOS
Unzip java3d-1_5_1-macosx.zip and open the directory it creates
Unzip j3d-jre.zip and open the new directory /lib/ and the subdirectory /lib/ext/
Move vecmath.jar, j3dcore.jar, and j3dmath.jar to ~/Library/Java/Extensions (this requires an admin password) or any other location
Run the following line in terminal:
open ~/.bash_profile
Go to the bottom and add the following:
export CLASSPATH="/path/to/vecmath.jar:$CLASSPATH"
import javax.vecmath.* to any .java program you want
The jar file can go where you want, moving it to your project's lib folder is good. The real issue is you need your classpath to point to it.
Here is a full explanation.
If you are running from the command line you don't need to set the classpath variable, you can provide it in the java command. It would be something like this:
java -cp lib/vecmath.jar Example
This assumes that the program you are working on has been compiled into a class file named Example.class. If you main method is in a package you will need to fully qualify the classname so it might look like:
java -cp lib/vecmath.jar com.demo.Example
You can list multiple jar files on the classpath, separated by a colon (:).
You can also ask for help in the command line by invoking:
java -h
Related
I'm new to Java11/all the overcomplicated module stuff.
The Problem
So I exported my Java11/JavaFX11 program from Eclipse as a Runnable JAR. If I click the JAR, it runs perfectly fine (Eclipse includes all of the module settings and JavaFX itself automatically in the runnable JAR). However, if I try to bundle the JAR with a JRE and run it via the command line with the following BAT file:
#ECHO OFF
%~dp0\jre\bin\java -jar javaprogram.jar
pause
I get:
Error: JavaFX runtime components are missing, and are required to run this application
Press any key to continue . . .
How can I get it to just run the JAR file like it does when I click it?
Ways I've tried to fix it
The weirdest part is, if I just use:
java -jar javaprogram.jar
Which just accesses the installed JRE, it works again. It's only when I'm directly pointing it to a JRE at a specific path that it appears to break.
Alternatively, I'd just bundle JavaFX beside the JRE, but there doesn't seem to be a way to call --module-path with a relative path (googling this nets me a bunch of entirely unrelated stuff). It seems to demand an exact path, which isn't going to work if people are downloading a zip archive and extracting it. This would be redundant though because Eclipse is already packaging JavaFX with the JAR. I don't know why it's getting confused just because I'm calling it from the command line.
The project's code
The project I'm trying to get this to work with happens to be open source, so you can check out the code for it here:
https://github.com/SkyAphid/JDialogue
The main class is JDialogueCore.
Closing
I don't want to use installers since I think that's too bloaty. I'd like to be able to deploy my software like I always have by just putting them in an archive you can extract and run.
It's difficult to simply Google the problems as well since I keep getting completely unrelated results due to the broadness of the topic. Any direction/documentation relating to this problem would be greatly appreciated.
Thank you for your time!
While Java 8, 9, and 10 allowed a JavaFX Application subclass to act as a main class for program startup, that is no longer the case as of Java 11. Placing your public static void main method in a different class and making that class the main class solves the problem. (Source: https://github.com/javafxports/openjdk-jfx/issues/236)
Your command line invocation needs to specify both the location of the JavaFX jar files, and the location of JavaFX native libraries. Normally these are the same location in the JavaFX SDK, but they must be specified in different ways: the jar files go in the classpath or module path, while the native libraries’ location must be specified in a system property:
cd /d %~dp0
jre\bin\java -cp javaprogram.jar;javafx-sdk-11\lib -Djava.library.path=javafx-sdk-11\lib com.example.MyNonApplicationClass
If you define a module-info.java in your program, your .jar is a modular .jar, and you can benefit from the additional security of modules:
cd /d %~dp0
jre\bin\java --module-path javaprogram.jar;javafx-sdk-11\lib -Djava.library.path=javafx-sdk-11\lib -m com.example.myapp/com.example.MyNonApplicationClass
If your modular .jar file has a main class defined, you can omit the class name:
cd /d %~dp0
jre\bin\java --module-path javaprogram.jar;javafx-sdk-11\lib -Djava.library.path=javafx-sdk-11\lib -m com.example.myapp
Notice that relative paths work just fine with --module-path. Relative paths use the current directory as a base. The current directory is not changed merely by putting %~dp0 in front of the invocation of Java. The current directory is a property of the command line or script actively running, and can only be changed with commands like cd or pushd.
Normally I can use javac to compile and java to run perfectly fine, they are set correctly into my computer's classpath. In this instance however, one of my files Graph.java is trying to import a jar file in the same directory Heap.jar.
When I try to use javac *.java, it tells me package mycs1 does not exist.
Normally in my lab on Linux machines, we can use export CLASSPATH=mycs1.jar:. and then javac will work normally again, and just add more files if there are more jars.
My problem is that this command does not work on my home computer running Windows 10. I am trying to set the classpath of multiple jars. This is similar to this question:
Unable to execute jar file despite having PATH and CLASSPATH set
But despite reading that, I still cannot find a way to set the path of multiple jar files in such a way that javac will work.
Is this possible? If not, what alternative command can I use?
I have a simple MyHelloWorld.java file within a directory myhelloworld. I set the classpath to appropriate direcotries by exporting CLASSPATH='[some needed class]' in my ~/.bashrc file. and I still need to use javac MyHelloWorld.jaca -cp 'the above classpath' to compile the .java file.
So here's my first question, why do I still need to explicitly set classpath by having a -cp option given the CLASSPATH is already specified?
After the file was compiled, I saw no file like MyHelloWorld, but the java commmand can autocomplete 'java MyHelloWorld' when in fact there's no file named MyHelloWorld exists within the directory? (If I typed "java MyH", the command can be automatically completed).
When I tried to execute 'java MyHelloWorld', it prompted me there's NOClassDefFoundError, which was an indicator of missing library. However when I tried to do 'java -cp MyHello', The command wouldn't complete itself, suggesting it couldn't find anything executable at all
So what are the reasons for above confusing signs. Can anyone take from here and explain to me how java deal with classpath and package, etc. Thanks!
Follow the java tuturial and especialy this section.
The section about JARs is for you too.
I built an application in Netbeans 6.8 and made project.jar file. When I run it, it works only on my computer, but not on any other computer. However, when I made any simple application, that doesnt use any libraries, it works fine on any computer.
Is there any way, how to invoke some error message, where is the problem?
My project use R 2.9.2, so I install this version on other computer and set the System Path variable exactly same. Other libraries listed in lib directory are: AbsoluteLayout.jar,DatePicker-V0.99-2006.09.01.jar,jcommon-1.0.16.jar,jfreechart-1.0.13.jar,jmathplot.jar,JRI.jar,pdf-renderer-1.0.5.jar
Thank you
You don't get any message at all? What do "works" and "not works" look like?
You sound like another person who hasn't taken the time to learn how to do things by hand on the command line without an IDE. I'd recommend doing that. Open a command shell and type in the java -jar -cp ... foo.jar command to run your stuff. The messages you get back will be educational.
Note the -cp command line argument. That's how you add your JARs to the CLASSPATH properly.
I solved this problem as follows, maybe it will help someone.I add 2 paths in PATH system variable:
Start -> Control Panel -> System -> Advanced
Click on Environment Variables, under System Variables, find PATH, and click on it.
In the Edit windows, modify PATH by adding the location of the class to the value for PATH.
you must add both paths, to jri.dll and r.dll, in my case it were these:
C:/Program Files/R/R-2.9.2/bin/;C:/Program Files/R/R-2.9.2/library/rJava/jri/;
I have added these lines already, but with different different slash. So be careful, you must use it / not \ to define path!!!
In my code I have the following statement import com.apple.dnssd.*; and compiler (javac) complains about this line. It writes that the package does not exist. But I think that it could be that "javac" search the package in a wrong place (directory). In this respect I have two questions:
How can I know where javac search for the packages?
I think that it is very likely that I have the above mentioned package but I do not know where it is located. What are the typical place to look for the packages?
ADDED:
On another Windows machine I tried the same thing and the "javac" does not complain (as before I compiled without any options like "-cp"). I check values of the "classpath" environment variable. It is equal to "C:\Program Files\Java\jdk1.6.0_18\bin;.;..". I went to the first classpath directory and did not find there something that could be the "com.apple.dnssd" library (no jar files, no files containing "apple"). So, I do not understand why javac do NOT complain on the second Windows machine.
ADDED 2:
On the machine #2 I have installed Bonjour after JDK. On the machine #1 JDK was installed after Bonjour.
ADDED 3:
On the machine #1 (where I cannot import the package) I found the jar file (it is located in "C:\Program Files\Bonjour" and its name is "dns_sd.jar"). I tried to add the above mentioned directory to the PATHCLASS environment variable on Windows 7 (and I restarted the system). It does not help. I still cannot import the package. I also tried to specify the "-classpath" in the command line. It also does not help. Now I will try to reinstall Bonjour (as it was advised).
ADDED 4:
I have uninstall Bonjour and Bonjour SDK. I have reload Window. Then I have installed Bonjour and Bonjour SDK. I have reload the Window. It did not solve the problem. I still cannot import the package (javac writes that package does not exist). I have also copied the *.jar file to the same directory there the source is located. It does not work. I used "javac -cp .". It does not work. Now I am out of options. I do not know what else can I try. Can anybody help me pleas?
ADDED 5:
My classpath is: C:\Program Files\Java\jdk1.6.0_18\bin;.;..;"C:\Program Files\Bonjour"
I try to compile from this directory: C:\Users\myname\java\bonjour\example
I compile by the following command: javac ServiceAnnouncer.java
I get the following error message: ServiceAnnouncer.java:1: package com.apple.dnssd does not exist
ADDED 6:
Finally I have managed to import the library. I did it in the following way:
javac -cp "C:\Program Files\Bonjour\dns_sd.jar" ServiceAnnouncer.java
The important thing is that I have specified the jar file after the -cp (not the directory where the jar file is located). It works also if I replace "dns_sd.jar" by "*". So, my conclusion is that after the "-cp" I need to specify jar files (not directories).
Java/javac will search for classes in the classpath.
The default classpath covers the /path/to/jre/lib and /path/to/jre/lib/ext folders. Any classes and JAR files which are found there will be taken in the classpath. You can in theory put your classes and JAR files there so that you don't need to do anything to get java/javac to find them. But this is actually an extremely bad practice. It's recipe for portability trouble, because this isn't the same in all machines. Leave those folders intact.
Then there's the environment variable %CLASSPATH% wherein you can specify full paths to root folders where classes are located and/or full paths to JAR files (including the JAR file name itself!). Multiple paths are in Windows to be separated by semicolon ; and in *Nix by colon :. Paths with spaces inside needs to be quoted with "". Here's an example:
SET CLASSPATH = .;/path/to/File.jar;"/spacy path to some pkg/with/classes"
Note the period . at the beginning of the argument. This indicates the current path (the current working directory from where the java/javac command is to be executed). It will only find classes in the current path that way, and thus not JAR files! You need to specify full path for them. Since Java 1.6 you can also use wildcards to specify multiple JAR files in some path. E.g.
SET CLASSPATH = .;/path/to/all/jars/*;"/spacy path to some pkg/with/classes"
This environment variable is actually a convenience way to manage the classpath so that you don't need to type the same thing down again and again in the command console everytime. But this is only useful for new-to-java users and the cause of all future confusion because they will think that this is "the" classpath. This assumption is actually wrong and again the cause of portability trouble because this isn't the same in all machines.
The right way to define the classpath is using the -cp or -classpath argument wherein you actually specify the same information as you'd like to enter for %CLASSPATH%, i.e. (semi)colon separated and paths-with-spaces quoted, for example:
javac -cp .;/path/to/File.jar;"/spacy path to some pkg/with/classes" Foo.java
Note that when you use either -cp or -classpath (or -jar) arguments, then java/javac will ignore the %CLASSPATH% environment variable (which is actually a Good ThingTM).
To save the time in retyping the same again and again, just create a bat or cmd file (or if you're on *Nix, a sh file). Basically just put therein the same commands as you'd enter "plain" in the console and then execute it the usual platform specific way.
To save more time, use an IDE. The classpath which is to be used during both compiletime and runtime inside the IDE is called the "build path". Explore the project properties and you'll see.
http://java.sun.com/javase/6/docs/technotes/tools/windows/classpath.html
To answer your first question (How to know where javac searches for packages):
Check what your $CLASSPATH variable is set to.
echo $CLASSPATH
This is where you JRE will search for class files and resources. You can either set it as an environment variable,
set CLASSPATH=path1;path2 ...
or set it when your run javac.
C:> javac -classpath C:\java\MyClasses src_dir
(Great examples for javac are found here)
In this case, your jar file containing 'com.apple.dnssd.*' should be located in your classpath. Just download that jar, and put it in the place where your classpath is searching.
Assuming that dns_sd.jar is installed in 'C:\Program Files\Bonjour', then try to compile your code like this:
cd C:\Users\myname\java\bonjour\example
javac -classpath C:\Program Files\Bonjour ServiceAnnouncer.java
This link suggests that the JAR containing this package is part of Bonjour for Windows. Look for it there.
javac.exe only searches where you tell it with the CLASSPATH. If you don't understand how to set CLASSPATH, I'd recommend reading something like this.