I am Cleaning and Building a project, which is creating its .jar file in its "dist" folder. However the issue is that, I'm not able to run it. I double click on it and nothing happens.
I have set up "bin" folder of JDK in "Path" option in environment variables.
Is there is anything that I am missing? I am new to all this and help is really appreciated.
Suggested
Learn how to make executable file yourself , rather than depending on auto generated jar file
Here is a tutorial.
In case of default jar file ,
most likely you have to execute
java -jar MY_AWESOME_JAR_FILE_NAME.jar
There are 3 common reasons for this:
On windows, and using sysin/sysout
Windows, because apparently microsoft is not capable of fixing ancient silliness, forces upon apps that they either have a terminal in which case an ugly black box always pops up, or they don't, and can't later make one. That means that on windows only, there are 2 java executables: java.exe and javaw.exe, with as only difference that javaw doesn't get a box. But, it doesn't get a box - sysin and sysout do pretty much completely nothing.
By default, double clicking a jar starts it with javaw, which means if your app's only interaction is reading from System.in and writing to System.out or System.err, you won't see anything.
There is no fix to this, other than to make a GUI app, or make a batch file (a windows only concept) that explicitly runs java.exe.
This doesn't apply to linux or macs.
jar file broken
A runnable jar file is one that has three properties:
There is a class inside the jar that has a public static void main(String[] args) method inside.
That class is named (fully qualified) in the manifest of the jar, under key Main-Class
Any deps needed are either baked into the jar, or in another jar, and those other jars are named, space-separated and relative to the dir that the jar you're double clicking lives in, in the manifest, under key Class-Path. Note that the global environment variable CLASSPATH does nothing when double clicking jars.
You can check all this; jars are just zip files. Also, the jar tool in your JDK can unpack them, and the manifest is just a file named META-INF/MANIFEST.MF inside. You can open it up, have a look if it's properly configured.
java install broken
Check any random runnable jar first. Maybe you installed a headless java. Note that these days (since JDK9 and up), an 'end user' wouldn't even install a java and the notion of double clicking a jar to run it is basically obsolete. To make 'desktop' java applications, you'd ship an entire JRE (treeshaken if you want) and you're responsible for an installer. There are some limited tools in the JDK (since 9) that help you out (such as jlink).
Use the CLI to see whether your Java is set up properly, the jar is corrupted, or the jar is incompatible with installed Java version.
Ensure the jar file is properly associated with Java binary. The instruction can be found here
Just edit manifest file adding main method in there. If you have any additional reference libraries simply put them into class path there.
Manifest specificatin is located here:
https://docs.oracle.com/javase/tutorial/deployment/jar/manifestindex.html
Related
Okay so basically, every time I've seen this question asked it doesn't have the answer I'm looking for which is why I'm trying to ask myself.
Basically, I made a java project on BlueJ (required by school, sadly. But I can export it elsewhere if that's the problem (preferably IntelliJ or Visual Studio Code)), but essentially, I want to make it so I can simply double click my .jar export and it will open a terminal window and launch. When I try this however, I get this error: First Error
And when I click Ok then this appears:
Second Error
Now, if I want the jar to run on terminal, doing java -jar jarFileName.jar works perfect, but what I want is for that to happen when I double click the jar file; for it to launch and run from the terminal.
All the other answers I've seen for this problem blame the users computer and usually tell them to install some version of java or whatever, but this isn't the problem. I have other jar files that I can run perfectly fine, like Minecraft Forge installer or Minecraft Spigot installers (sorry only examples are Minecraft, not much else uses Java). And also this was for a uni project and no one else in my field know how to get their jar to be executable, nor does this file work for anyone else.
So yeah, I know it's a problem with how the jar was compiled or something and not what java is installed my PC.
I just want to make it double-clickable for the convenience of when I send it to friends, but if anyone knows another way I can get around this problem then that's fine. For example I know I could make a Bash file which simply does the java -jar jarFileName.jar for me or something, but I'd rather have it all as one jar file, so I don't know if this can be incorporated into the file but yeah.
Also I'd really like a solution which doesn't involve downloading external programs or whatever, since all I want to do is send this file to my friends and have them just double click it to launch.
TL;DR, what do I have to do to make my jar file actually executable by double clicking it. Thank you.
To make a jar file executable you have to set the entrypoint
You can do this by passing the e option to the jar command when you create the jar file, for example:
jar cvfe myapp.jar com.mycompany.myapp.MyApp com\mycompany\myapp
This will add the Main-Class entry in the jar's manifest pointing to the startup class, which should have a main method, for example:
package com.mycompany.myapp;
public class MyApp {
public static void main(String[] args) {
// start up the application
}
}
When you create a JAR file, it automatically receives a default manifest file. There can be only one manifest file in an archive, and it always has the pathname
META-INF/MANIFEST.MF
The entrypoint is specified by the Main-Class, for example:
Manifest-Version: 1.0
Created-By: 1.8.13_37 (Oracle Corporation)
Main-Class: com.mycompany.myapp.MyApp
If you want to make an existing jar file executable you could unzip it, modify the manifest and zip it again (and rename it so it has the .jar extension - a jar is just a zip).
But I think the errors you show are not caused by the jar not being executable, but by some environment issue, causing the Java application to not find the necessary variables or paths to make the Java Native Integration (JNI) work. To solve this you would have to provide more detail on what you are trying to do with JNI.
I'm re-using a standalone Swing-based Java class which backs up and restores mysql databases.
I've tested running it from a Windows batch file (.bat) on my dev system, and it works there.
But, if I run the batch file on a different Windows , I get a "main class not found" exception.
However, when I run the command directly on the command line, it works.
The command in the batch file to run it is:
java -cp lda-services.jar;bip-services-1.6.0.0-SNAPSHOT.jar;decryptor-1.6.0.0-SNAPSHOT.jar;slf4j-api-1.7.31.jar;commons-io-2.6.jar com.ilcore.util.SosaMaintenanceJFrame
The SosaMaintenanceJFrame class is contained in the lda-services jar.
Here's the error message:
Error: Could not find or load main class com.ilcore.util.SosaMaintenanceJFrame
Caused by: java.lang.ClassNotFoundException: com.ilcore.util.SosaMaintenanceJFrame
The class is definitely in the jar file, as I've extracted it the file and seen it.
Any thoughts on why this would be happening? I need to run inside a batch file so the user can just click on it to run it.
Most likely explanation
Your paths are relative, which means that the batch file isn't going to work unless you run it from the right place. In general, having a batch file that has an invisible rider stapled to it with: "I break in mysterious ways if not run from the appropriate dir" is a crappy batch file - make it better.
Better solution
Or, even better, get rid of it. You don't need batch files to distribute java programs.
Proper ways to distribute java programs:
The modern take is very very different from what you have here: JREs are dead, you must ship an installer that does the whole thing, notably including a java runtime (no longer called a JRE, and one you ship and keep up to date if relevant). That's perhaps a bridge too far for what you're doing here. Relevant tools include jlink.
A slightly less modern take involves jars with manifests:
Your jar file should contain a manifest. This manifest must contain 2 relevant entries:
Class-Path: lda-services.jar bip-services-1.6.0.0-SNAPSHOT.jar decryptor-1.6.0.0-SNAPSHOT.jar slf4j-api-1.7.31.jar commons-io-2.6.jar
and
Main-Class: com.ilcore.util.SosaMaintenanceJFrame
You can use jar's -m switch, or just include the manifest (it's just a file in the jar): it's at META_INF/MANIFEST.MF and it's a text file, each line is an entry, and an entry consists of a key: value pair.
When a jar contains this, just double clicking the jar and running java -jar thejar.jar will then take care of it all: Java will load the stated jars as part of the classpath, and these, crucially, are resolved as paths relative to the directory the jar is in, so it DOES work when you try to launch them from elsewhere, i.e. if you do:
C:
CD \
java -jar "c:\Program Files\MyApp\myapp.jar"
it works fine, whereas that batch script would fail due to being in the wrong place.
Build systems let you define the manifest too, check your build systems docs for how to do this, it'll be easy, and there are tons of tutorials if you search the web for e.g. 'manifest executable jar maven' or whatnot.
You can consider making a shaded jar. But I wouldn't.
A shaded jar takes all your dependencies and packs them into your main jar, so that there is only one jar. There is now no need for a Class-Path entry (the jar you run is obviously already on the classpath and there's nothing else to include) and your app is shipped as 'just' a single jar file.
But this is mostly a red herring: There are no consumer JREs anymore so you've made the user experience from a D- to a D. If you actually care about giving your users a nice experience, there's no getting around an installation process of some sort and once you have that, having the separate jars is no longer a problem. Separate jars are less hairy when signed jars are involved, are much easier to keep up to date, and have a significantly faster turnaround (when you build your stuff and want to ship what you built, shading takes ages, so it's nice to cut that step out). The faster your CI system tells you about failing tests, the better.
Meet in the middle
You don't have to upgrade to modules and the like. What you can do instead is use something like launch4j. The aim is to end up with a zip file along with the installation instructions: Make a dir somewhere. unzip this zip in it. Doubleclick 'myapp.exe'. Done.
The zip would contain an entire JRE, all your jar file deps, and your main app, and an exe file which launch4j made for you, that launches your app using the JRE packed into the jar. This means you know exactly which JRE is being used, and it'll work even on systems that didn't have one installed yet (which, these days, should be all of them - the notion of 'end user downloads a JRE from oracle and the user + oracle work together to keep that thing up to date and security-issue-free', is dead).
The fact that it's an EXE is nice: Now if the user e.g. alt+tabs through their apps, they get your app, with your name, and your icon, instead of 'javaw.exe' with an ugly coffee mug logo.
But when I try running it from the jar file generated by Maven, however, I get a "class not found" exception.
Even if you didn't get that error, you'd get another one unless you'd used Maven Shade, as that's the only way you're going to run that with a single jar. My guess as to why that particular error occurs is that the app class you're attempting to run is in fact in one of the *SNAPSHOT* jars
I currently wrote a simple GUI in Eclipse which runs as intended. I was hoping to export it so I can share it with my friend (who doesn't need to install eclipse and the java libraries). I tried all 3 library handling method Eclipse provides and none of them works. I read a little online and saw something about a manifest file, but wasn't quite sure what to do with it. Is it going to help?
This is where I placed the folder that comes with the .dll file.
This is the result. Am I doing something wrong?
As indicated by the error messages in the first screenshot, what you are missing here is the native library - the software library written and compiled to native code specific to the operating system. What you will need to do is provide the libraries specific to the operating system on which your software will run, eg. dlls for 32 or 64 bit Windows. The manifest does not provide the capability to include those libraries.
When the program is run on Windows, Java will look for native libraries in the following locations:
The current directory
The directories in the PATH environment variable
The directories in java.library.path (if it's specified)
It may be easiest to simply put all files in the one directory. If you do this, you should be able to run the program in the same way as you do now.
The java.library.path option is only needed if you want to put your native library files in a directory separate to the one in which you run your program and not on your PATH. It is only in this case that you will need to add java.library.path, eg. by adding -Djava.library.path=c:\path\to\your\lib after java. Also note that you may use a relative path, ie. a path that is relative to the directory you are in when you execute the command.
I also see from your later error messages that you have another dependency, but on a java library LeapJava.jar. As running a jar with -jar will only work if you have a single jar, but because you have more than one (your own program plus the dependency), you'll instead need to use the -classpath (or -cp for short) argument and add your main class. The classpath argument is a semicolon-separated list of classpath locations, while the main class is the one containing your public static void main method, eg. your.package.name.YourMainClass. So assuming your UI.jar is still in C:\Users\Ian\Desktop\Leap Data UI, you should be able to navigate to that directory and execute with:
java -cp UI.jar;UI_lib\LeapJava.jar -Djava.library.path="UI_lib\x64" your.package.name.YourMainClass
I've done a search and I can see that a lot of people have had the same problem as me, but none of the solutions have worked for me.
Basically I have a Java Project in Eclipse that is from my old Windows Installation. I've cleaned and rebuilt it because at first it wouldn't compile, but now I have it exported as a Runnable Jar. However, the only way I can get the application to appear is to do java -jar foo.jar in command prompt, or run it in Eclipse. If I double click the JAR in Windows Explorer nothing happens even though I know that Java is associated correctly because other Runnable Jars work.
The project only has the x86 JRE listed in it's Build Path Libraries and all the files listed appear to exist. I'm running Windows 7 HP.
Update: I'm sorry, but I just discovered that no other Runnable Jars are working either. If they are wrapped with launch4j they work though...
Edit: The Runnable Jars that I export from Eclipse do work fine on other systems and load on double click
Some registry values or file associations are probably messed up. Wiping off all of your existing JRE's and JDK's and re-installing them should fix your issue.
Alternatively you may be able to fix it by manually editing the registry value here:
HKLM > SOFTWARE > Classes > jarfile > shell > open > command
My value is
Type: REG_SZ
Data: "C:\Program Files\Java\jre8\bin\javaw.exe" -jar "%1" %*
You'd of course want that path to point to your javaw.exe, and make sure you have the additional arguments.
I was also facing the same problem while i was working with Spring tool suite.
You may use the following steps:-
Right click on project -> export -> Runnable jar file -> (Here,In library handling,there are three options,you have to choose middle one i.e package required library into generated jar.It will package external dependency also).
-In my case, my runnable jar was only executing on my environment i.e on which i have created that JAR. Initially i have selected the first option to create JAR i.e extract required libraries into required JAR.but that was not proper.
It may help you.Let me correct if i am getting wrong.
Since you are able to run the JAR running the command line, I believe your issue is related to which version of Java is set to run the file when it is double-clicked.
To find out which version is successfully running the file from the command line and set it to open JAR files by default:
Open a new command prompt window.
Run echo %path%. Among the path values, you should be able to find one pointing to the bin folder of one of the installed versions of Java. Copy this path somewhere.
Navigate to the JAR file you would like to run. Right click the JAR -> Open with -> Choose default program... -> Browse...
Browse to the path you copied in step 2. (the easiest way is to paste it into the address bar)
Double click javaw.exe.
Click OK.
You should now be able to run the JAR file. Please let me know if your problem persists.
I have made a jar with and keep it on desktop.Then,I double clicked on the jar and it working fine for me.
How I and what I have monintored: In my main class, perform some operation and at the end I add on Thread.sleep(25000); to hold the program for few moments. After every double click on the exported jar I found one new javaw.exe process added in the system process tree. I have noticed it on Task manager. and after 25000ms respective javaw.exe process ended. As my application does not cointain any GUI that's why I have not seen any GUI changes for the respective process. I'm Confident that if my application have some GUI, I will surely get the respective GUI window on every run.
Common mistakes : when we export a project from Eclipse as Runnable JAR file, it is exported with selected Eclipse launch configuration and Eclipse specific launch wrappers. Now if the configuration does not match when you are trying to run it via double-click you will not be able to see the error, If you run it from CMD then surely you will get the error log.
To create standard executable JAR file : To create a standard executable JAR file, you can export as JAR file and specify the main class in last screen of the wizard.
That's working for me fine. I used the same jar from different system and keeping it different location.
I would like to ship my application as a self-contained jar file. The jar file should contain all the class files, as well as two shared libraries. One of these shared libraries is written for the JNI and is essentially an indirection to the other one (which is 100% C).
I have first tried running my jar file without the libraries, but having them accessible through the LD_LIBRARY_PATH environment variable. That worked fine.
I then put the JNI library into the jar file. I have read about loading libraries from jar files by copying them first to some temporary directory, and that worked well for me (note that the 100% C library was, I suppose, loaded as before).
Now I want to put both libraries into the jar, but I don't understand how I can make sure that they will both be loaded. Sure I can copy them both to a temporary directory, but when I load the "indirection" one, it always gives me:
java.lang.UnsatisfiedLinkError: /tmp/.../libindirect.so: /libpure.so: cannot open shared object file: No such file or directory
I've tried to force the JVM to load the "100% C" library first by explicitely calling System.load(...) on its temporary file, but that didn't work better. I suspect the system is looking for it when resolving the links in libindirect.so but doesn't care about what the JVM loaded.
Can anyone help me on that one?
Thanks
One way would be to spawn another Java process from the first, generating the appropriate invocation script.
The jar is invoked by the user
The libraries are extracted to a temp directory
A (bash) script is written to the temp directory
this sets/exports the necessary environment variables
this launches the second JRE instance
The code makes the script executable
The code invokes the script
I know, spawning two JRE instances to launch one app would not be my first choice either.
If you are using Eclipse IDE, then this answer might help you.
I had same problem in eclipse windows that I couldn't added dependant .class files from the JNI.
After searching for a while I came to know that "Its a known bug inside Eclipse", In order resolve the same, I ported all the code to NetBeans IDE.
Can not add all the classes files from the JNI folder in Eclipse (JAVA, Windows 7)