I'm trying to use VS Code with java, but I have an issue.
As a student, my teacher gives me a file named Clavier.class.
I have already wrote a programm with another IDE, and when I execute it in the command of Windows, it works without any problem. But, when I put this programm in VS Code, it doesn't recognize Clavier.saisirInt, which is a static method in Clavier.class. I guess that VS Code can't use a class which is in a File.class, but is there a way to make it works ?
Here is an image of my workspace and you can see the error at the bottom
I assume your lib/ folder is placed onto the execution classpath. If this is the case, that's where compiled class files should go, not next to your sources
Otherwise, you'll need to inspect the java command that actually runs your code to see what/if the -cp argument is set to, or include those class files similar to how the documentation shows for JAR files (which are just zipped packages of class files, and honestly what the teacher should provide instead)
By default, VS Code will reference all JAR files in workspace's lib directory using the glob pattern lib/**/*.jar
And so, you need to adjust this to include lib/*.class after moving your files there
I read and searched almost everywhere, yet i have no answer.
I have a project with multiple .java files, and i need to export them as a single .jar file.
One of the main questions is based on the fact that i don't have a main class.
What can i do to go through that ? Shall i create a main but never run it? Or there's any way around?
Offtopic ( might be usefull): i want to do this in order to use the jar file in IKVM
Thank you!
You do not need a main method to create a jar. There are many such jars out there such as utilities packages. They don't contain any code that would make sense to execute on it's own since it only contains code that makes your application easier to write.
First compile your code using Netbeans or command line javac utility. This will give you .class files.
Now for creating the jar... You can simply create the jar (which is basically a glorified zip archive) by using the command-line jar tool.
jar -cvf my archive.jar myprogram/
Make sure that the file path within the jar archive match the package name of the classes. It is not uncommon to accidentally get an extra layer of directories.
You probably should have searched stackoverflow first since how-to-create-a-jar-file-in-netbeans seems to cover exactly what you're looking for.
Do you want to use the jar as a external library or a program itself?
If it will be a external library, you don't need a main class. In eclipse you can export as a jar file (select classes-> right click-> export as jar).
If it will be a program itself, then you need a main class.
You really need to create main class file, write code in function main(String args[]) which use your java classes and compile it by javac.
I have a Java application that was converted to an .exe with launch4j. For several reasons I need to get access to the class files of the application.
The first thing I tried was unpacking the exe with 7zip. That way I get a handful of class files, but definately not the whole application packed in the exe (the class files seem to belong to launch4j).
What other options are there?
You can use something like this to extract the JAR from the Launch4j executable:
http://www.nirsoft.net/utils/resources_extract.html
Typically the executable packages necessary JAR's as executable resources and then looks for a JDK on the path to execute.
Once you get the JAR file you should be able to decompile it.
You cannot get access to class files. Exes are created, So that nobody can get access to your code.
If somehow , you are able to get access to jar files then you can decompile them to get the code and make changes.
I have written a Java program that uses Java swing library. Now I would like to execute this program by double clicking on the executable file on Windows just like any other program with a GUI. How do I do that?
Since it is Java based and has a GUI, the obvious answer is to deploy it using Java Web Start.
Java Web Start (JWS) is the Oracle Corporation technology used to launch rich client (Swing, AWT, SWT) desktop applications directly from a network or internet link. It offers 'one click' installation for platforms that support Java.
JWS provides many appealing features including, but not limited to, splash screens, desktop integration, file associations, automatic update (including lazy downloads and programmatic control of updates), partitioning of natives & other resource downloads by platform, architecture or Java version, configuration of run-time environment (minimum J2SE version, run-time options, RAM etc.), easy management of common resources using extensions..
By 'desktop integration' read desktop shortcuts and menu items on supported platforms.
The 2 icons on the right (JotPad & Star Zoom Animation) are both Java based apps., installed using Java Web Start. Since JotPad is sand-boxed, the user will be prompted as to whether to create the shortcut. That choice is not offered for apps. with higher permission levels, so it would make more sense to install/remove the shortcuts and menu items using the IntegrationService - which allows an app. (after prompting the user) to create/remove them at run-time.
There are number of options:
Create an executable jar of your project. for this jar to work you have to have javaw as default application to open it.
Create an exe of your project.
Create a bat file which runs your jar file.
Take a look at this: How can I convert my Java program to an .exe file?
While the others mention excellent choices like creating a native executable, there is another useful method: creating a shortcut.
Right click your desktop, expand the "New" option, and click on "Shortcut".
Type "javaw.exe". Click next.
Name it whatever you want. Click done.
You'll notice the newly created shortcut on your desktop. Right click it and choose "Properties"
In the "Target" textfield, append "-jar path-to-your-jar.jar" where you replace "path-to-your-jar.jar" with the actual path to your jar
You can also now optionally change the icon to whatever icon you want
This shortcut can be pinned to the taskbar and be used from anywhere (considering you provided an absolute path to your JAR).
you need to create exe from the java program.
Creating executable jar files
First, make sure you have installed Java 1.2 or above. This facility is not available in previous versions of Java.
Next, create your working java system. In general, you will want to put it into a package. For this example, I created a trivial HelloWorld application that prints out "Hello World" plus the first command line argument, and placed it into the package "psae". Therefore, the HelloWorld files (HelloWorld.class, HelloWorld.java) were located in the directory psae. I tested the system to make sure it worked before going on to the next step.
In the directory in which the psae is located, created a file called "mainClass". This file contains a single line specifying where the main Class is to be found in the jar file. Note that I use the package specification. Here is the single line:
Main-Class: psae.HelloWorld
Note: make sure you type a carriage return after this line; some windows systems need it and will report a "Failed to load Main-Class manifest attribute" error.
Next, I create a jar file called psae.jar using the "jar" command in Java2. I use the "m" command line argument to specify the manifest file mainClass, which adds information to the jar file on where the main class will be found. Here is the jar command:
bertha:~ > jar cmf mainClass psae.jar psae
Just for fun, and to check what's happened, I print the table of contents for the jar file I just created. Here's the command and its result:
bertha:~ > jar tf psae.jar
META-INF/
META-INF/MANIFEST.MF
psae/
psae/HelloWorld.java
psae/HelloWorld.class
Having successfully created the jar file, I can now invoke java2 on it with the command line argument:
bertha:~ > java -jar psae.jar Philip
Hello World Philip
There are a few projects, like http://jsmooth.sourceforge.net/ and http://launch4j.sourceforge.net/
you can use something like Launch4j.
also look at JSMooth.
Hope it helps
There are two ways. Both involve packaging your code in a .jar.
The first way is to build an actual .exe file using a tool like Launch4j. It will require you to set up things like tell it which class to execute, which icon to use, which JRE is OK, what JRE parameters to use, etc.
The second option is to make the .jar itself executable. You do this by adding a manifest to the .jar. The manifest is a small configuration file that describes the jar. One of the attributes is Main-Class which defines the entry point. In other words, it says which class has the main function that should be called when the user double-clicks the file.
Here's a basic tutorial about manifests: http://docs.oracle.com/javase/tutorial/deployment/jar/manifestindex.html
The 2nd option is easier to get going, but users will know what to do with a .exe far more often.
Note that if either approach complains that it can't find the class, make sure to set the classpath manifest attribute to match your project.
If you have an executable jar file, just shift-right click on your file and set it to be opened by javaw. The other option (in case you want to pass in parameters to your application) is to create a .bat file where you spin off your application via java or javaw
Right click to your "project" in eclipse and select "export" then choose "Java->Runnable Jar File" select your project name and finish.
Seems you want to deploy and run the standalone application of swings. Being a java developer you should understand the power of jar files. Those are executable in themselves {so no need to create .exe files :)} .
The below code will help you to create a jar file.
Creating a jar File in Command Prompt
Start Command Prompt.
Navigate to the folder that holds your class files:
C:\>cd \mywork
Set path to include JDK’s bin. For example:
C:\mywork> path c:\Program Files\Java\jdk1.5.0_09\bin;%path%
Compile your class(es):
C:\mywork> javac *.java
Create a manifest file:
C:\mywork> echo Main-Class: NameOfProject >manifest.txt
Create a jar file:
C:\mywork> jar cvfm NameOfProject.jar manifest.txt *.class
Test your jar:
C:\mywork> DanceStudio.jar
After creating a jar just double click on it and you are done.
You have to create an executable jar file. For that you just simply add a META-INF folder to the jar, then add a MANIFEST.MF text file with two lines:
Manifest-Version: 1.0
Main-Class: your.package.YourMainClass
Here's how to run a Java program by RIGHT-CLICKING on it (in other words, from the Windows Explorer context menu). This handy trick is great for beginners who need to test their simple programs on the fly. Works on both Win7 and XP rigs.
[ATTN: Depending on the situation, you may need to remove the package directive from the top of your Java file.]
Step 1. Create a batch file (e.g., RWJ.bat) inside a folder of your choice (say, in C:\Program Files\Java.)
Step 2. Fill RWJ.bat with the following commands (they will work just fine as is with simple classes but you can, of course, tweak them according to your particular needs by specifying compiler / interpreter switches, passing args, adding echo off, removing pause or whatever):
javac %1
java %~n1
pause
The first command passes the full name of your right-clicked file to the Java compiler; the second one strips the file extension and feeds JVM with the class name only.
Step 3. Add the following key to your Registry: HKEY_CLASSES_ROOT\*\shell\Run With Java and then create its command (default value):
C:\Program Files\Java\RWJ.bat %1.
Step 4. Run your Java class by right-clicking it and selecting Run with Java option.
That's all there is to it.
Another way to run Java programs by pointing and clicking is to use AOT compilers. For example, GCC has an entry point named GCJ, which can be used to compile the source code into both byte codes and standard executable file for your particular OS.
And finally, instead ot batch files one can run WSH, etc.
I have a .java and .class file which i put under a folder inside my pydev project in Eclipse (because im primarily using python).
Inside my python script i wanted to call the java class file using os.system.
os.system('java -mx1500m D:\\projects\\socialsense\\src\\ss\\samplefile\\test')
However it says that my class file is not found. What is wrong?
I expect that you can do that. However, most people would probably put the java source and python source in separate directory trees, and also not put .class and .java files in the same tree. (If you lump everything into the same place you'll cause yourself pain when you try to implement a "clean" rule in your build file ... or when you want to check your project into version control.)
Your immediate problem is that you've got the command syntax for the java command wrong. The name of the entry point class is specified by giving a fully qualified class name, not a pathname. And you probably need to use the -cp option as well.
For details on how to do this right, refer to the java manual page.