Develop Reference

run java program created in intellij from command line

I have a simple Java Maven program that I created in Intellij. It has Two classes Main and Read. I was able to build a jar and run it. However if I zip the source code into a folder , would I be able to compile it using command line? Something like javac ? How should I do this? Shall I run commands in Java folder in the project? Many thanks.

As far as the Java class loader is concerned, a .jar or .zip file is the same as a directory containing the the files, and .jar and .zip files are generally used to distribute compiled Java packages. Here you can read more about it.
For compiling the zip file: use the -classpath option to javac and java. We could, for example:
javac -classpath .:/users/johnr/java:/opt/jdk1.1.6/lib/classes.zip Hello.java

Create .class file from a jar file -java

I am using Java8. I have one .jar file containing .class files.
I downloaded the source code of the same .jar file. And I edited one of the file in it. It is .java file.
Now I want to compile all these .java files in the source code and create a new .jar file with .class files
Any clues?

There are many options
1. if you want to do it from command prompt then you would need to set the classpath and then either create a list of java files with package name and use it for compiling, something like this
# Linux
$ find -name "*.java" > source.txt
$ javac -classpath "${CLASSPATH}" #source.txt
:: Windows
> dir /s /B *.java > source.txt
> javac -classpath %{CLASSPATH}% #source.txt
or use build tool like Ant.
Once you have the .class files, you can use "jar" command to create a jar of the .class files
2. Use IDE - you can use any of these IDEs - eclipe, intellij, netbeans.
You need to setup a project with the java files and compile project and export as jar using class files.
I think it would work out better for you to use an IDE.

1) Compile the classes (javac command)
If you don't have any jar dependencies required at compile time, you should not need to set the classpath.
Otherwise you should specify the cp argument with.
Example (Unix way) :
javac -cp "myLib.jar:myOtherLib.jar" *.java
2) Then create a jar from these compiled class (jar command)
Example :
jar cf myjar myFolderWithCompiledClass

extract your jar to a folder and run this:
javac [folder]/*.java
read that for more info:
https://docs.oracle.com/javase/7/docs/technotes/tools/windows/javac.html

how to use JDatePicker jar file into the program

I need to use 'JDatePicker' class for a program. I downloaded 'jdatepicker-1.3.2.jar' file. and when i extracted the file using the command "jar xf jdatepicker-1.3.2.jar", I got 3 folders in the directory " META-INF, tutorial, net". But i don't know how to import this to the java program and where to store this jar file and the extracted folders. could any one assist me on the above?
I don't use any IDE. I run the java programs in command prompt

You must have that exact jar file on the class path. When compiling specify jar in the compile
javac -classpath jars\jdatepicker-1.3.2.jar -sourcepath src\project -d classes src\project\MyProg.java

Need help building a Selenium Java Class file from cmd line

I'm trying to cmd line compile a .java selenium test script into a class file that I can run from the command line.
All of my selenium jar files and all other supporting jar and lib files are in C:\JarFiles
My CLASSPATH is set to C:\WDJarFiles*
I am working at the command line here: C:\EclipseIDEworkspace\MC3\src\Tasks
My .class files are located here C:\EclipseIDEworkspace\MC3\bin\Tasks and I'd like to be able to update them at that location.
My folder structure was set up by using Eclipse IDE so I'd like to keep the existing folder structure but now I want to be able to compile my .java files from the command line and update the .class files.
So, when I run javac like this:
javac Edit.java
It compiles OK and the .class file gets created in the same folder where I am running the javac command -- but -- I also get a huge number of other .class files in this same directory! These look like supporting class files.
I'm not sure what my cmd line javac syntax should be to:
Compile my .java file so its .class file gets updated in the C:\EclipseIDEworkspace\MC3\bin\Tasks folder.
I don't get all those other .class files created in my working folder C:\EclipseIDEworkspace\MC3\src\Tasks
Thanks for any help...

You should try the '-d' option to specify an output directory:
javac Edit.java -d ..\..\bin\Tasks
About the multiple other .class files, you probably have many nested classes into your Edit.java file?

Program runs fine in IDE but not as Jar file

I have exported a jar file that I want to run the console. The code compiles and runs correctly in eclipse but I am having an issue running it from the console.
To me it looks like the referenced jar's I added via built path in the Eclipse project file and not being added to the export. If that is the case, how do I ensure that they do? If not, what am I doing wrong?

When you export your source code's class files to a jar using eclipse, only the .class files of your source are exported! Hence your exported jar file doesn't contain the referenced jars you mentioned in eclipse! Due to this, the error occurs while executing from command prompt.
Solution:
Take all the jar files required to execute the program, store it in the same directory as you store the exported jar file. Now while executing the java command, provide all the jar file's names in classpath field as following:
java -classpath .;JAR1.jar;JAR2.jar MainClass
Once you do this, your problem should be resolved!

The dependencies need to be on the classpath, i.e. run like this:
java -cp <path_to_jar1>;<path_to_jar2> -jar ScrumTimeCaptureMaintenence.jar

When running from the command line make sure any dependencies are set on the class path by listing them in the -classpath parameter