Is it possible to execute a JAR file on any OS (like Windows, Linux, Mac OS X)? I want to build a simple application that I want to run on Linux, Windows, and Mac OS X. Could the JAR file be run on any OS with java installed?
The Jar files run on any OS for which a JVM exists.
Yes, as long as you don't use any native libraries (JNI) this is how java works. It's platform independent.
As other said, as long as you have Java installed and avoid using native code, you should be good to go. One thing to note is that you can usually run a JAR file just by double clicking it, and it opens like a native executable (on Windows this is how it works by default, on other OSes you can configure this behavior).
Such JAR files are called executable JAR files. If what you want to create is an executable JAR file, then you need to add a manifest file that tells the Java virtual machine (JVM) the name of the main class. Executable JAR files also can be run on the command line by doing:
java -jar myprogram.jar
If your JAR is not an executable JAR, then to run your program you have to add the JAR to your classpath and then execute the main class. To add a JAR to the classpath:
java -classpath path/to/your/program.jar com.mypackage.Main
Jar files are designed to run on any OS that has a JVM of a compatible version installed. Some jar files, however, may have be compiled from Java code that used OS-specific code (say talking to Windows registries), so testing it on other OS's is wise.
Yes, it can as long as it's not ruining from the terminal or command prompt (like java -jar name.jar.) it should work just fine.
Related
I have created a java program (in Eclipse). I have successfully compiled it to a .jar file which I can run on windows without any problems. I want to give this program to a friend who has a MacOSX. So my aim is to:
Create a file which can be run on MacOSX
The twist is that I have to configure it on my Windows computer since I don't have access to a Mac. Any advice would be of great help!
I am not sure what you are referring as "create a file which can be run on macOSX"
If you want to run on any OS you just need a JRE on that particular system without it you cant run. It will provide a runtime environment to run a jar file. Then use below command to run the jar.
java -jar Myjar_file.jar
I have tried the following:
in terminal it works
In Intellij it works
I have tried to launch it with javaw.exe but nothing changes
Are there any other options?
This looks like an OS problem that an application building one -- because you said that it works in your IDE and terminal.
Make sure that you installed Java properly in your machine.
In Windows/MacOs, after installing Java, the *.jar files are automatically associated with the java -jar command and makes it runnable via double-click.
In linux, this varies on the flavour or DE you are using. But there's probably a utility in your OS to open *.jar files using java -jar command.
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.
so apparently if you create an executable jar, in order to run it you still need the java command:
java -jar something.jar
but what if I just want it to run without the java command, so just directly from the command line
something.jar
is there a way to export my java app in eclipse in order to accomplish such
On Unix systems you can append the jar file at the end of an executable script.
On Windows you have to create a batch file.
For instance in Unix:
$cat HelloWorld.java
public class HelloWorld {
public static void main( String ... args ) {
System.out.println("Hola mundo!");
}
}
$cat M.mf
Main-Class: HelloWorld
$cat hello
#!/bin/sh
exec java -jar $0 "$#"
$javac HelloWorld.java
$jar -cmf M.mf hello.jar HelloWorld.class
$cat hello.jar >> hello
$chmod +x hello
$./hello
Hola mundo!
In windows you have to create a batch file like:
::hello.cmd
javaw -jar hello.jar
Which has the same effect.
On Windows and OSX you can double click on the jar to run it, I'm pretty sure you may add a trigger on Linux too.
I hope this help
Excelsior JET - http://www.excelsior-usa.com/jet.html - claims to compile to native code and bring its own runtime support, so it does not require an existing JVM. Commercial product.
I have not tried it myself, but they have spent quite a bit of effort over the years to market JET as a great deployment method for precompiled binaries.
Also note that if you have an executable/runnable jar which works fine with "java -jar someting.jar" and you just want to be able to invoke it in a more convenient way, this is the job of the program accepting your command and launching the java command.
For Linux you can frequently add an alias saying that "something" expands to "java -jar something.jar", and some command interpreters allow for saying that all commands ending with jars should be executed specially. The exact details depend on which shell (command line interpreter) you are using.
What you need is a tool called 'Java Executable Wrapper'.You can use it to Pack all your class files to a Single Executable Package.
The One i recomment is launch4j,you can download it from sourceforge launch4j.sourceforge.net
Launch4J can be used to create standalone Executables (.exe) from a jar file for windows Environment.
The thing is, that Java gets interpreted by the JVM, so you'll at least need to ship it with your app.
To be a little more specific about this, Java gets kind of compiled to byte-code so it can be interpreted faster. But the Byte-Code can't run without the JVM. This is the nice side of Java: You don't need to recompile your Apps to run on other platforms like Linux or OS X, the JVM takes care of that (as it is written in native code and is recompiled for those platforms).
There are some compilers out there which can convert your Java code to something native like C which can then be executed without the JVM. But this isn't the idea behind Java and most of those tools suck at what they do.
If you want your App to run without any interpreter, you'll need to use a compiled language like C or C++
Java program runs on a JVM, for the first question I don't think there's a compiler that can do the job well. For the second question since a jar file is not an executable per se, there must be some sort of settings in the target machine, "executing" a jar file without providing the java command is a matter of convenience for the user. On Windows every file extension has a program associated with it, so .doc documents have (usually) Word as the program associated -that setting is set by the office installer, the java runtime also sets the setting for .jar files when you install it, but behind the scenes, java command will be used by the system. So the short answer to the second question is: depends on the target machine.
I have created a java application and packed it into a jar file on a Windows platform. Now I wants to deploy that jar file on Debian Linux.
Will the same jar file work for Debian Linux?
Is the command, used in windows for executing a jar file from the command prompt, same for Debain Linux?
i.e.
java -jvm "MyJar.jar"
Will the above command work for Debian Linux?
Generally, it should. However this depends on a few conditions:
If you use native code (JNI) you must make sure that the native library is available for the target platform
You must make sure you have no paths hardcoded which are Windows specific (in fact you should even watch out for special characters like the Path seperator : vs. ;)
You cannot use Runtime specific code
Yes.
Jar files are portable across platforms, and the syntax of the jar command is the same on both Linux and Windows.
EDIT: You should use the latest version of Sun Java unless there is a very good reason not to. Installation instructions: http://wiki.debian.org/Java/Sun
1. Will the same jar file work for Debian Linux?
Yes. Hence the nature of Java (portable code)
2. Is the command, used in windows for executing a jar file from the command prompt, same for Debain Linux?
java -jar "MyJar.jar"
yes, the main idea of java is that it (should) run on different operating systems, as long as a java runtime is installed.
though i have never heard of the -jvm flag.
if you want to start a jar file you should use the -jar flag.
java -jar "MyJar.jar"
you can also read up on the Write once run anywhere principle.
I do my development on a mac but run in linux and windows environments without any problem. Key is not to use JNI, As everyone else have mentioned I would use java -jar "MyJar.jar"
Almost. Use:
java -jar "MyJar.jar"
And of course you shouldn't have used anything such JNI or runtime stuff
Yes, although you might want to do, in Linux:
java -jar YourJar.jar
Instead of:
java -jvm YourJar.jar