Develop Reference

Java command line using an imported jar

I am sure this is a stupid question and it must have been asked by every java programmer before. But I cannot find a related question at all.
This talks about subdirectories but I don't have any subdirectories as they are all in the same directory as the java file and the directory I executed the command line from Executable jar file error
This solution gives me the same error as I am writing below: Java command line with external .jar
Others (I don't have links to) talk about Eclipse and other IDE but I am not using an IDE, just a Linux terminal.
I am trying to import a public jar file from http://www.hummeling.com/IF97. The downloaded jar file has been renamed to if97.jar.
I have a java file called steam.java with these commands inside the file:
'
import com.hummeling.if97.IF97;
IF97 H2O = new IF97(IF97.UnitSystem.ENGINEERING);
System.out.println("test H2O table PSpecificEnthalpy(1): "+H2O.specificEnthalpyPT(1,300));
System.out.println("test H2O table PSpecificEnthalpy(5): "+H2O.specificEnthalpyPT(5,300));
'
But I do not know how to run this file in the command line.
I successfully compiled by typing:
'javac -cp if97.jar ~/test/steam.java'
Now I have a file called steam.class
But when I execute it with:
'java steam -cp if97.jar'
or
'java steam -jar if97.jar'
I get error:
Exception in thread "main" java.lang.NoClassDefFoundError: com/hummeling/if97/IF97
at steam.start(steam.java:364)
at steam.main(steam.java:341)
Caused by: java.lang.ClassNotFoundException: com.hummeling.if97.IF97
I am trying to execute this in Linux Ubuntu 16.04 using Terminal. Both the files (steam.java and if97.jar) are in the same Home directory where I execute the javac & java command on.
I believe (or I'm mistaken) that the problem is that java isn't able to find the jar file. But I don't know why.
Please advise, thank you in advance.

You need to specify the class name after the JVM options, because whatever coming after the class name are considered arguments for the class, not the JVM.
Try this:
'java -cp if97.jar steam'

.jar file is not working after being published from Eclipse [duplicate]

There was a program that I used that made runnable .jar files.. All the ones I'm finding now are ones that make .exe files.. I remember it also has the option to make the file a .sh script as well. Anyone knows its name? I've been searching for hours with no avail :/

The command line
java -jar file.jar
Will run your jar file if it has a Main-Class defined as explained here.
You can use that command in a shell script.

You can create a runnable jar using NetBeans IDE or Eclipse IDE by just providing the main class to run. Rest of the things it will take automatically. That class must be having a main() method in it. Then you can run that jar file using java -jar yourjarfile.jar

Do you mean actually coding java and then compiling to .jar? If you do try
eclipse code editor
I used eclipse to make minecraft mods. It will work if you want to make .jar programs.

If you want to have a jar that you can execute using the usual syntax ./app.jar (instead of java -jar), here is a post explaining the process: how to create executable jars.
Basically, JAR is a variant of ZIP, which allows random bytes to be pre/appended to the JAR without corrrupting it. This means it is possible to prepend a launcher script at the beginning of the jar to make it "executable".
Here is a simple example of the process:
# Append a basic launcher script to the jar
cat \
<(echo '#!/bin/sh')\
<(echo 'exec java -jar $0 "$#"')\
<(echo 'exit 0')\
original.jar > executable.jar
# Make the new jar executable
chmod +x executable.jar
With this, you can now run ./executable.jar instead of java -jar original.jar. This works on all unix like systems including Linux, MacOS, Cygwin, and Windows Linux subsystem.

Cannot run a .jar file

I'm having issues when I try to execute a .jar file. I always get the message from the command prompt "cannot find or load main class" every time I try to run the file I have just compiled.
I have tried the following(using the command prompt and saving the java code with Notepad++ and creating the manifest.txt file in the same folder where the .java code was saved):
javac classname.java
java cfm classname.jar manifest.txt classname.class
java -jar classname
I have also tried:
javac classname.java
java classname
And:
java packagename.classname
After compiling the .java file
I know there are hundreds of questions like this in the forums, but I have looked everywhere and I keep getting the same error. I just cannot run the .jar file even after I create it.
It's probably something I have missed but I am out of ideas.
Manifest:
Main-Class: classname

Let's see.
java -jar classname.jar
would work if your MANIFEST.MF calls out the correct class.
java -cp classname.jar my.package.MyClass
would work in any case.

Jar file execution

Suppose I made a program to take two input and display the sum.
It runs in netbeans but when I build out the jar file , and
double clicked the jar file , nothing happens.
How can I make these program run?

You must run this from command line, and then execute java -jar {PATH_TO_JAR}

You can use the command-line :
java -jar <yourjar> <yourMainClass>
You can also add the main class in a manifest file into the jar. Doing so, you don't need to specify anymore on command line

Jar files needs to run in JVM - Java Virtual machine, to run your file use:
"java -jar" and your jar.
By doing so, you tell Java to run your jar in jvm which means it now can run.

Java: System.out.println() should write to the console, but it doesn't

I am trying to write Java console application, the code is quite simple:
public class ConsoleTest {
public static void main(String[] args) {
System.out.println("test");
}
}
If I run this application from Eclipse, then i see "test" in Eclipse's "Console", but if I export my app as a "Runnable JAR file" and run it from Windows XP cmd.exe, then nothing is echoed to the console.
On the safe side, i tried to check System.console(), it returns null.
What can be wrong?

How are you running your program outside eclipse?
You should use command line like
java -jar yourjar.jar
or
java -cp yourjar.jar ConsoleTest
If you are occasionally using javaw instead no console output will be produced. The STDOUT of javaw is null. Probably this is what happens when you are clicking on your jar file.

You need to run your jar file from the command line.
If you double click on it, you wont be able to see the command line operations being run in the background. Jar files are usually run by double clicking only when they involve GUI.
To run a jar file from a command prompt, just do this:
java -jar ConsoleTest.jar
Assuming you've set environment variables for java.exe and the current directory has the jar file.
If this doesn't work, then it is likely not your code's fault.
There is also the chance that the manifest file pointing to the Main class was set up incorrectly.

Try compiling it into a class from the command line and then running it. Does that work?
javac ConsoleTest.java
java ConsoleTest

Chances are your runnable jar file isn't working as you expect and isn't actually running your ConsoleTest class.

Like what Hovercraft Full Of Eels wrote, compile the .java file using cmd.exe with the following command:
javac ConsoleTest.java
Then this will create a .class file, and we want to compile it with this command:
java ConsoleTest
It should then display the "test" output.

you have to install the java jdk and add the root of the directory containing the file java.exe to your system's directories, you will find further informations in the jdk's installation guide.
and then run the file in the console with the command
> java file.java