Develop Reference

Compiling a package-structured Java program with jars from terminal

I need to be able to compile and run a Java project from the terminal, and without using something like Maven or Gradle. The project structure looks something like this:
project
src
package1
Main.java
package2
Class1.java
Class2.java
bin
lib
jar1.jar
jar2.jar
Main.java contains the main() method, and it needs Class1 and Class2 in order to run. It also needs the .jar files jar1 and jar2, located in the lib folder. I would like all of the .class files to be in the bin folder.
I've tried my hand at figuring out the terminal command in order to compile and run the program but am a bit stuck. This is the best I've managed to figure out:
cd project
javac -d bin/ -cp lib/jar1.jar:lib/jar2.jar src/package2/*.java src/package1/*.java
This successfully compiles, but then when I try to run Main.java:
java -cp lib/jar1.jar:lib/jar2.jar src/package1/Main
I get the following error:
error: invalid flag: src/package1/Main
Usage: javac <options> <source files>
use --help for a list of possible options
Could someone explain to me what I'm doing wrong?

java Could not find or load main class from eclipse compiled code

I have compiled my java code using eclipse but not it has to be deployed and a cron job has to execute it. I am trying to execute it from command line in Windows, but getting Could not find or load main class. I tried setting classpath using java -cp bin\com\pega\download\engineclasses but it still throws the same error. My folder structure looks like below
C:\Users\s2517457\G360_Linux\FiddlingPega
|__\bin\com\pega\download\engineclasses\TestUtils.class
|__\src\com\pega\download\engineclasses\TestUtils.java
Please let me know what should be the javac and java commands for this to work.

You should use the following command:
java -cp bin/ com.pega.download.engineclasses.TestUtils
Your are telling to java that the entire bin folder is your classpath and the main class is in the class com.pega.download.engineclasses.TestUtils
If you want to add jars as well, you must call the command like:
java --classpath "bin/;lib/*" com.pega.download.engineclasses.TestUtils
Where lib is the folder containing the Jars files

Compiling multiple .jar files with .java class

I currently have a java class which I am attempting to compile using Linux terminal along with a folder (/libs) which contains about 9 .jar folders.
I am struggling trying to attempt this.
I am aware of how to compile a single library to a class:
javac -classpath /libs/example.jar MyMainClass.java
just unsure of how this can apply to multiple libraries.
Thanks.

You can either refer to an entire folder containing all the libraries such as javac -cp lib\* MyMainClass.java
Alternatively, you can refer individual libraries as such: javac -cp lib1\Library.jar;lib2\Library.jar MyMainClass.java (separate with semicolon)

compiling a packaged project dependent on a jar

This seems to me to be a trivial question, but I've had a lot of trouble getting an answer.
I've developed a project in eclipse that is dependent on a jar file, which resides in the project's root directory. All my files are in a package "a.b.c" in a src folder. It runs just fine in eclipse. I now want to run this project from the command line. I do this command to compile the project:
javac -classpath dependency.jar -d ./bin/ ./src/a/b/c/*.java
Everything is compiled into class files and put into the bin/a/b/c folder. Then I do these commands to run the project:
cd bin
java -cp ../dependency.jar a.b.c.Main
Now I get "java.lang.NoClassDefFoundError: a/b/c/Main".
So, how do I run a project that is in a package and depends on a jar file?

Just include the current dir in the classpath as well - i.e. java -cp ../dependency.jar:. a.b.c.Main

You also need to specify your compiled files on the classpath, these will contain your a.b.c.Main. On *nix flavor machines the path separator for cp is the colon (:), and on windows it's a semicolon (;), so on *nix, your run command should be (because you're running from the bin directory):
java -cp ../dependency.jar:. a.b.c.Main

Compiling four java files within one package using javac

I have four java files in my folder. They are all in the same package. Here's the package declaration
package com.osama.GHide
All of these classes are in the same package. I want to know how can I compile them using javac (i mean i do not know how to compile multiple files that are using each other). And once that is done how do I launch then using java command in the CLI? here are the file names.
EnteringPoint.java
HidingProcess.java
ListFiles.java

From the project's root directory:
javac src/com/osama/GHide/*.java
To run, assuming no other dependencies:
java -cp ./src com.osama.GHide.EnteringPoint
(Assuming EnteringPoint has the normal main function.)
The javac command compiles all the .java files in the package's directory. Since they're all in the same package/directory, this works. It also puts the generated .class files in the same directory, which may or may not be what you want.
To put them in a different directory, use the -d option and supply a path.
javac -d bin src/com/osama/GHide/*.java
Then to run:
java -cp ./bin com.osama.GHide.EnteringPoint

You can run by using command :- javac -cp src/com/**/*.java
I am asuming there is no other dependenices and your root class name would be src only.