We Keep Coding

How can I get stdlib.jar to work in IntelliJ IDEA?

I​ had used the IntelliJ IDEA installer provided in the booksite for Computer Science: An Interdisciplinary Approach and I had no problem to use the library. However, I noticed that installation had screwed my Git bash display settings, so I uninstalled everything.
Later, I installed the latest version of IntelliJ (2021.3.3), from the JetBrains website and apparently all the previous settings were overwritten, since I could no longer use the library. So, I downgraded back to the version provided in the booksite, however, I still can't use the Std library.
I've tried adding the versions of the library .jar files that I found:
On the Standard Libraries Princeton's webpage
On the Jar Download website
On this post from Stack Overflow
In the .jar file from the hello.zip file I found on this other Princeton webpage
Together and independently to the module and libraries, via IntelliJ IDEA, following the paths: "File > Project settings > Modules > + > JARs or directories" and "File > Project settings > Libraries > + > Java" , respectively, and choosing the corresponding directory/file, with no luck, since I've got the "cannot find symbol" error message:
Barnsley.java:16: error: cannot find symbol
StdDraw.setScale(-0.1, 1.1); // leave a 10% border
^
symbol: variable StdDraw
location: class Barnsley
For literally every single mention of the Std libraries in the code. I​ also tried editing the environment system variables and created a variable named "CLASSPATH" and linked it to the Stdlib.jar file and then, to the .lift folder that came with the hello.zip file, from the first week assignment. Again, no luck, because I kept getting the same error message.
Next up, I typed:
javac -cp stdlib.jar Barnsley.java
In the command line, and although that command itself didn't lead to any error message, when I tried to run the program, typing:
java -cp stdlib.jar Barnsley 10000
This error message showed up:
Error: Could not find or load main class Barnsley
Caused by: java.lang.ClassNotFoundException: Barnsley
I also vainly tried copying and pasting every .java file from Standard libraries webpage to the same directory where I keep the program files.
I know some (maybe lots of people) have asked the same or a similar question before, either here or in other forums, but I've been googling and looking for a solution for three days now and, as you can see, none of the reported solutions that I've found have been of help to me, that's why I decided to ask again, on my own.
Thank you for reading my post and/or for any help you can provide.
PS.: The Barnsley.java file in the error messages corresponds to the one provided in the 5th section of this webpage from the booksite.
[Edit - April 7th, 2022]:
I tried to follow #CrazyCoder advice, so I created a folder named "src", extracted all the files from the stdlib.jar file that came with the hello.zip file into src and also moved Barnsley.java to that folder. Next, Next, I tried to follow the instructions from the webpage he mentioned, as shown in the following screenshot:
And somehow, got the same error message when compiling:
I don't know what went wrong :C Any assistance would be highly appreciated.
[Edit - Later on April 7th, 2022]:
Something weird happened. I downloaded the file provided by #CrazyCorder and there was a warning about Amazon Corretto not being installed, that I decided to ignore.
I tried to run the program from the command line, with no luck, because I got the same error message as always. So, I noticed that there was no JDK assigned to the SDK slot in the Project structure, and I chose to use JDK 18 (following the path "File > Project structure > Project"), which is the one that I had previously installed on my computer, but that didn't really change a thing.
Lastly, I tried to run it from the IDE and that's when it finally worked!!! So, thank you, #CrazyCoder :D I still don't know why it doesn't work from the command line, though...

I also vainly tried copying and pasting every .java file from Standard libraries webpage to the same directory where I keep the program files.
This works just fine, you need to place all the .java files from the stdlib.jar into the sources root directory (marked in blue in the project view). Barnsley.java needs to be in the same directory.
The jar with .class files will not work in the dependencies/classpath as you cannot import classes from the default package in Java.
It was an extremely poor choice to keep the classes in the default package and it's the fault of the creators of this library/course. This simple oversight has caused major headaches over the years.

Matlab Compiler MCC errors on imports for Java classes from dynamic Java classpath

How can I get mcc to recognize imports from user-provided Java libraries, or to simply ignore unresolvable imports?
I have a Matlab codebase that I'm building with the Matlab Compiler, but the build is breaking because mcc is erroring out when it encounters import statements for Java classes that were in JARs on Matlab's dynamic classpath. I am including all the JAR files on the classpath with the mcc -a option. The code works in the IDE, and I think it will work in the deployed app, if it will only allow me to build. (Works under R2009b, which ignores these imports in non-MCOS classes.)
Here's a simple repro. This file is in the same dir as guava-11.0.1.jar from Google Guava.
%file hello_world_with_import.m
function hello_world_with_import
import com.google.common.base.Stopwatch;
disp('Hello, world!');
end
Running it in Matlab works fine. But building it fails. (The javaaddpath here is not strictly necessary in the example, because bad imports by themselves are not an error in plain Matlab. Just showing how it works in practice, and how I wish mcc picked up on it.)
>> javaaddpath('guava-11.0.1.jar');
>> hello_world_with_import()
Hello, world!
>> mcc -m -a guava-11.0.1.jar hello_world_with_import
Error: File: C:\Temp\import_test\hello_world_with_import.m Line: 3 Column: 8
Arguments to IMPORT must either end with ".*"
or else specify a fully qualified class name: "com.google.common.base.Stopwatch" fails this test.
Unable to determine function name or input/output argument count for function
in MATLAB file "hello_world_with_import".
Please use MLINT to determine if this file contains errors.
Error using mcc
Error executing mcc, return status = 1 (0x1).
This is in Matlab R2011b on Windows.
Some background on my environment. My app has about 40 JARs on the dynamic classpath which are a mix of third party libraries and our own Java code. It's deployed to 50+ users on a mix of single-user and multi-user Windows machines. And there are other groups that may be deploying other MCR apps to the same users and machines. On any machine, different MCR apps may be run concurrently by the same or different users. We do weekly releases, and (mostly due to changes in our own Java code) at least one JAR file changes about every other release. I need a mechanism that will work in this environment.
Any suggestions? Anybody know a good way to get mcc to add stuff to its java classpath in the compilation step, or just ignore bogus imports? My fallback plan is to go through the codebase and remove all the imports for Java classes, which is kind of a pain.
UPDATE 12/2/2012: I heard from MathWorks that this is fixed in Matlab R2012b. (But I'm no longer using Matlab so can't personally verify it.)
UPDATE 12/09/2014: I'm using Matlab again (R2014b), and the Matlab Compiler now includes JARs that are on the dynamic classpath in the compiled program's dynamic classpath. It doesn't seem to automatically include the JAR files in the archive, though; you must manually include them using an mcc command line switch, or adding them as "additional included files" in the Matlab Compiler app.

The code executing in the MATLAB IDE works because the guava jar file has been added to the "dynamic" classpath via the javaaddpath method. However, when you use MCC to invoke the MATLAB Compiler, it does not rely on the dynamic java classpath, but the "static" java classpath which is defined in:
$MATLABROOT/toolbox/local/classpath.txt
If you add an entry for your JAR file here, then MCC will be able to resolve the IMPORT line in your M-File.
So to test this, I downloaded the guava jar file and tried the steps above. Works like a charm.
Also, If you read the "Troubleshooting" section for the MATLAB Compiler, this exact situation is documented:
http://www.mathworks.com/help/toolbox/compiler/brtm1xm-8.html
Quoting from the link: "The import statement is referencing a Java class () that MATLAB Compiler (if the error occurs at compile time) or the MCR (if the error occurs at run time) cannot find.
To work around this, ensure that the JAR file that contains the Java class is stored in a folder that is on the Java class path. (See matlabroot/toolbox/local/classpath.txt for the class path.) If the error occurs at run time, the classpath is stored in matlabroot/toolbox/local/classpath.txt when running on the development machine."

You just have to put import statements in a separate .m file.
so from:
javaaddpath 'c:\some.jar';
import com.something.Element;
...interesting stuff...
There will be a do_imports.m:
import com.something.Element;
And in original .m:
javaaddpath 'c:\some.jar';
do_imports
...interesting stuff...
And then it will compile and work. No need to mess around with system-wide classpaths.

Here is an extract from the link
http://blogs.mathworks.com/desktop/2009/07/06/calling-java-from-matlab/
MATLAB maintains a path for Java classes separate from the search path. That means even if you have a .class or .jar file on the MATLAB path, unless you use javaaddpath you will not be able to use it. To see what is currently on the path use javaclasspath. Running this command you will show you a long list of files that ship with matlab called the Static Class Path and then you'll see the Dynamic Class Path. The dynamic class path is where classes added to the path with javaaddpath will be placed. They can be removed with javarmpath and have to actively reloaded each session of matlab.

compiling multiple java classes in linux

i used netbeans to code the classes and they are all included in a package but when i try to compile the application class in linux it spits out errors on class definitions for the classes i am working with. points at the class names for the objects and says "cannot find symbol" i need help!!!

use javac -sourcepath < your source code path >
Better check -help option as it mostly solve your problems

cd to the directory containing your package then run:
javac -classpath . your_package_name/*

I'm not a Java guru, but I have a small java project that I developed years ago and have recently ported to compile with javac on Linux.
I got this to work in two different ways:
Created a single Java source file that held all of my classes
Put each of my classes in a separate file but all in the same directory
In each case, I can compile and run with the following:
javac *.java && java name_of_main_class
Notice that I did not specify a "-classpath" option when I compiled. I guess this works because I have not used a directory substructure or created a package. If you are dealing with those issues, this page appears to have some examples that may help you: Help with packages in java - import does not work
A key thing to understand about Java packages: They correspond to subdirectories where the classes are defined (or to JAR files which just bundle and compress those subdirectories into a single file). Therefore, anytime you specify the package keyword in your source, you need to make sure that the source files (and the class files) are distributed to subdirectories correspondingly. The -classpath option to javac may provide a workaround when subdirectory structures do not exactly match what is specified by the package keyword.

If you built the project using NetBeans, you can use Ant to build the project on command line. NetBeans generate Ant Build script.
just cd into the directory where the project is located then type 'ant'
it should build the project for you automagically

trying to compile after using eclipse and having import problems

hi
i'm using ubuntu and i have a little project with several packages i wrote in eclipse.
when i am trying to compile (run javac) from the terminal i get numerous errors like:
Writeable.java:14: cannot find symbol
symbol : class IllegalFilterArgumentException
location: class oop.ex1.filters.Writeable
throw new IllegalFilterArgumentException();
now in eclipse everything was fine. i was told its because i need to run javac from a directory that can see all java files in my project, but it didn't work. any ideas? thanks

If you are using packages (as you are, from the error message), you must arrange your source files in package structure, and then call javac from the root of this structure. For example this way:
root directory
oop
ex1
filters
Writeable.java
IllegalFilterArgumentException.java
Then you'll call it this way:
javac oop/ex1/filters/Writable.java
Alternatively to "calling from the root directory" you could pass this root directory as an option to javac:
javac -sourcepath "root directory" oop/ex1/filters/Writable.java
(You may also want to give other options to javac, look at its help page.)

Using custom .jar's in your java project

I'm importing from two jar's twitter4j-2.0.10.jar and mysql-connector-java-5.1.10-bin.jar, I'm running the code on a server but it's not letting me. I get a..
Streamer.java:9: package twitter4j does not exist
import twitter4j.StatusDeletionNotice;
^
error when compiling. I know this has something to do with getting java to recognise my custom jar's but I don't know how to get java to "see" them.
Any ideas?

You need to set the classpath for Javac.
One possible example (Windows, with your jar files in a folder called "lib"):
javac -classpath lib/twitter4j-2.0.10.jar;lib/mysql-connector-java-5.1.10-bin.jar MyClass.java
That's a very precise example though, your environment could differ considerably.