I have a running java program which converts a json file into another file format. Everything works great.
For the implementation I decided to use the MVC pattern.
Now I want to implement the whole conversion routine so that I can use a command prompt but I never worked with that and don't know how to achieve this at all.
My thoughts were:
Open cmd and navigate to the main.java-file.
Print out the whole possibilities (the user should be able to enter the dir of the source file and the target dir, the user should be able to choose the target format).
If everything has been entered by the user, the conversion routine should be started by pushing ENTER.
Help would be really nice. For the moment I just know how to compile (javac helloWorld.java) and print "Hello World!" by exeuting a program with java helloWorld...
The apache commons cli project provides utilities for parsing command line arguments and providing help menu. This makes it pretty simple to handle the args provided to your main method.
You will also need to provide scripts to assemble your class path. You can look at the maven app assembler plugin for ways of doing this.
The interaction between a shell/command prompt and the started Java program is very similar to the way it works in C programs*. The main() method receives arguments as strings from the command line (or from any other parent process which executes the java runtime).
In Java you get an array of strings. You need to decide yourself which string has what meaning.
public static void main(String[] arg) { // traditional or String ... args
System.out.println("You have " + arg.length + " arguments);
if (arg.length >= 1) System.out.println("First: " + arg[0]);
}
When starting a Java runtime with arguments, it is important to note, that arguments start after the class name (or the JAR name):
java -cp . package.Main arg0 arg1 ...
java -jar package.jar arg0 arg1 ...
The Java runtime also has an mechanism to specify system properties on the command line. This is done with the -D option.
java -Dverbose=yes -jar package.jar arg0 arg1 ...
java -jar package.jar -Dverbose=yes arg1 ... //not a system property but arg[0]
It is important, that this option is specified before the class/jar-name, otherwise it will not be processed by the runtime, but you will see another argument.
String verbose = System.getProperty("verbose", "false");
The reason why system properties are useful: you can use them for optional control, so you do not have to worry about recognizing arguments (there are a number of libraries out there which can do that but for small tools I think it is overkill).
BTW: there are some interactions between shells/prompts and started programs when using wildcards (* and ?) and whitespace/quoting - those are OS specific.
* in C the first argument args[0] is the program name, in java arg[0] is the first argument after the class name.
I made a console-based Java application but every time I try to start the .jar file by clicking on it the program seems to be running but there is no console displayed. Is there specific code I must write in order to call for the system console?
Can you start the console first , change directory to where your jar file is and then run java -jar yiurjarfilename ?
The OS takes care of displaying console output. There is no code that you can write within Java to display or hide the "console" (because within Java, there's only standard output & error streams that you write to).
Windows usually leaves the console open after your program exits, but there might be a setting within the Java Runtime Environment that configures that behavior.
gcivil is right, you can see the results in console only if you start from console, if you are in windows you can open the command line Super + R and type cmd, then press enter (Super is the one with the Windows icon)
there you can type : java -jar "absolute path to your file" (don't forget the quotes)
another way is create a .bat file next to the .jar one, the bat file should contain
java -jar filename.jar
you don't need the quotes nor absolute path since it is next to the .bat file now you can double click that instead of the .jar
Once the app is terminated it will close the console, if you need to see what is next you have to add pause
java -jar filename.jar
pause
I have this java program that I want to package within a jar.
It compiles fine and it compiles without errors into a jar. But when I double click it, it wont start. I know most jar applications uses JFrame and that works fine. But is it possible to make it command prompt/shell based? (Like Displaying System.out.println)
Example is it possible to execute this code by double clicking a jar:
public class Hello
{
public static void main( String[] args )
{
System.out.println( "Hello, World!" );
}
}
There is no problem doing like that. But where do you expect to see the output?
If you execute from the console as java -jar my jar.jar you will see your "Hello, World".
If you want to double-click you'll need to create a JFrame.
You can change the file association for jar files to have them open a console.
(This is for Windows)
Open Command Processor
Type ftype jarfile
You will get something like:
jarfile="C:\Path\To\Java\bin\javaw.exe" -jar "%1 %*"
Enter ftype jarfile "C:\Path\To\Java\bin\java.exe" -jar "%1" %* (You may need administrator privileges to do this).
I don't see anyone mentioning the obvious solution: make a .cmd (or .bat) file containing the command everyone is talking about -- java -jar YourJar.jar. You can double-click on the .cmd file and a console window will open. It will also close imediately as your program exits, so the program should wait for a keypress before exiting.
You can make a jar an executable by including a manifest file which contains the name of the class that has your main method (in your example that would be Hello). Here is a link that details what you need to do.
Sure. First try to run your program as following:
java -cp yourjar.jar Main
where Main is a fully qualified class name of your main class.
When this is working fine and if you creted exacutable jar try to run your program as following:
java -jar yourjar.jar
When this is working double click should work too unless you mapped extension jar to program other than javaw that is done by default when you are installing JRE.
If you want to display the "Hello, world!" String you have to execute your code from the command line:
jar -jar your_jar_name.jar
The output gets forwarded to the console but without eclipse, there isn't any! The only way to work around this is to launch the program in command prompt and then you will get the output from the program.
When i execute my java application i need to pass arguments which is needed by Java interpreter for Flash image.
for eg. java -sum_arg Demo
Now i want to create JAR file for my application and how can i overcome need of arguments.
You can pass arguments to Java applications packed into .jar files just as you can with single .class files:
java -jar MyApp.jar anArgument
If you care about the UI case where a user simply double-clicks the .jar file to run your application, then you might want to consider using a real UI (using Swing, for example).
A simple way to get input this way would be with a JOptionPane:
String myInput = JOptionPane.showInputDialog("Enter something!");
If you have not any class path dependencies
java -jar test.jar "arg1" "arg2"
If you have any class-path dependencies
java -cp classpath-dependencies -jar test.jar "arg1" "arg2"
In swing we can get parameter from command line argument.
public static void main(String[] args)
{
for(String arg : args)
System.out.println(arg);
}
I have a JAR file named helloworld.jar.
In order to run it, I'm executing the following command in a command-line window:
java -jar helloworld.jar
This works fine, but how do I execute it with double-click instead?
Do I need to install any software?
Easiest route is probably upgrading or re-installing the Java Runtime Environment (JRE).
Or this:
Open the Windows Explorer, from the Tools select 'Folder Options...'
Click the File Types tab, scroll down and select JAR File type.
Press the Advanced button.
In the Edit File Type dialog box, select open in Actions box and click Edit...
Press the Browse button and navigate to the location the Java interpreter javaw.exe.
In the Application used to perform action field, needs to display something similar to C:\Program Files\Java\j2re1.4.2_04\bin\javaw.exe" -jar "%1" % (Note: the part starting with 'javaw' must be exactly like that; the other part of the path name can vary depending on which version of Java you're using) then press the OK buttons until all the dialogs are closed.
Which was stolen from here: http://windowstipoftheday.blogspot.com/2005/10/setting-jar-file-association.html
In Windows Vista or Windows 7, the manual file association editor has been removed.
The easiest way is to run Jarfix, a tiny but powerful freeware tool. Just run it and your Java apps is back... double-clickable again.
If you need to distribute your .jar file and make it runnable at other people's Windows computers,
you can make a simple .bat file like this in the command prompt:
java -jar MyJavaTool.jar
and place the .bat file in the same directory as your .jar file.
If you have a jar file called Example.jar, follow these rules:
Open a notepad.exe
Write : java -jar Example.jar
Save it with the extension .bat
Copy it to the directory which has the .jar file
Double click it to run your .jar file
An interesting side effect of this causes a problem when starting runnable jar files in the command prompt.
If you try (in a command prompt):
jarfile.jar parameter
No joy, because this is being translated to the following (which doesn't work):
javaw.exe -jar jarfile.jar parameter
However, the following command does work:
java.exe -jar jarfile.jar parameter
If you change the association in file manager as described above to:
"C:\Program Files\Java\j2re1.4.2_04\bin\java.exe" -jar "%1" %*
Then you can type:
jarfile.jar parameter
in the command prompt and it will now work!
EDIT:(However you then get a black console window when you run a form based (non console) Java app, so this is not an ideal solution)
If you run these jar files by double clicking them in windows, no parameters will be passed so your Java code needs to handle the stack overflow exception and include a "press a key" function at the end or the window will just disappear.
In order to pass a parameter in windows you have to create a shortcut to the jar file, which includes the parameter in the target line (right click on the shortcut and select properties) you can not add parameters to the jar file icon itself in this way.
There isn't a single, consistent solution here, but you would have the same problem with any other console application.
There is a windows freeware application called "bat to exe" which you can use to create an exe file from a .bat file with the apropriate command line in it. you can also embed the jar file in the exe with this application, and make it clean it up when it has finished running, so this may be a more elegant solution.
First set path on cmd(command prompt):
set path="C:\Program Files\Java\jre6\bin"
then type
java -jar yourProgramname.jar
In Windows XP * you need just 2 shell commands:
C:\>ftype myjarfile="C:\JRE1.6\bin\javaw.exe" -jar "%1" %*
C:\>assoc .jar=myjarfile
obviously using the correct path for the JRE and any name you want instead of myjarfile.
To just check the current settings:
C:\>assoc .jar
C:\>ftype jarfile
this time using the value returned by the first command, if any, instead of jarfile.
* not tested with Windows 7
In regedit, open HKEY_CLASSES_ROOT\Applications\java.exe\shell\open\command
Double click on default on the left and add -jar between the java.exe path and the "%1" argument.
There is way without requiring user to do changes on his PC. Runtime.getRuntime.exec() allows us to start cmd.exe and execute commands inside of it. So, it's possible for java program to run itself in command prompt when user clicks .jar file.
public static void main(String[] args) throws IOException {
if(args.length == 0) {
Process p = Runtime.getRuntime().exec("cmd.exe /c start java -jar " + (new File(NameOfClass.class.getProtectionDomain().getCodeSource().getLocation().getPath())).getAbsolutePath() + " cmd");
} else {
//code to be executed
}
}
Besides all of the other suggestions, there is one other thing you need to consider. Is your helloworld.jar a console program? If it is, then I don't believe you'll be able to make it into a double-clickable jar file. Console programs use the regular cmd.exe shell window for their input and output. Usually the jar "launcher" is bound to javaw.exe which doesn't create a command-shell window.
I´m running Windows 7 x64 and was unable to use any of these fixes.
This one worked for me afterall:
http://thepanz.netsons.org/post/windows7-jar-file-association-broken-with-nokia-ovi
There is an archive which you can download containing a .bat file to run, but check the path of the actual javaw.exe!!!!
You want to check a couple of things; if this is your own jar file, make sure you have defined a Main-class in the manifest. Since we know you can run it from the command line, the other thing to do is create a windows shortcut, and modify the properties (you'll have to look around, I don't have a Windows machine to look at) so that the command it executes on open is the java -jar command you mentioned.
The other thing: if something isn't confused, it should work anyway; check and make sure you have java associated with the .jar extension.
Unfortunatelly, it is not so easy as Microsoft has removed advanced file association dialog in recent Windows editions. - With newer Windows versions you may only specify the application that is going to be used to open .jar file.
Fixing .jar file opening on Windows requires two steps.
Open the Control Panel, and chose "Default Programs -> Set Associations". Find .jar extension (Executable JAR file) there, and pick Java as default program to open this extension. It will probably be listed as "Java Platform(SE)". A faster alternative perhaps is straightforward right-click on a .jar file, and then change associated program by clicking on the "Change..." button.
Now open the regedit, and open the HKEY_CLASSES_ROOT\jarfile\shell\open\command key. Luckilly for us, we may specify parameters there for the (Default) value. On my Windows system it looks like: C:\app\32\jre7\bin\javaw.exe" -jar "%1" %* but in most cases it is the following string: C:\Program Files\Java\jre7\bin\javaw.exe" -jar "%1" %*
NOTES:
Do not use java.exe there as it will open the shell window.
The jarfix tool mentioned in this thread most likely does nothing more than the registry modification for you. I prefer manual registry change method, as that implies that system administrator can "push" the registry change to all workstations in the network.
Create .bat file:
start javaw -jar %*
And choose app default to open .jar with this .bat file.
It will close cmd when start your .jar file.
Got the same problem, on Windows 10
The solution:
Check your JAVA_HOME and JAVA_PATH.
https://javatutorial.net/set-java-home-windows-10
Use Jarfix to restore the assiciation between .jar and javaw.exe
https://johann.loefflmann.net/en/software/jarfix/index.html
I had the same problem in Windows 10. I fixed it using righ-click on the "helloworld.jar" and go to properties and click on change button under "Opens with:" and select "Look for another app on this PC". In the "Open with..." dialog box, go to your Java folder location on your PC and open corresponding jdk folder and then open the bin folder and select "javaw.exe" from there. Then next time your "helloworld.jar" will open the normal way.
Usual java location example : "C:\Program Files (x86)\Java\jdk1.8.0_111\bin".
Another way to run jar files with a click/double-click, is to prepend "-jar " to the
file's name. For example, you would rename the file MyJar.jar to -jar MyJar.jar.
You must have the .class files associated with java.exe, of course. This might not work in all cases, but it has worked most times for me.
PreScript: If your prompt appears and disappears immediately, the reason it does so is that your program gets executed and auto shut. Try putting a scanner in the end to terminate and it'll keep your prompt waiting for input before terminating. (Or use delay maybe)
Was in the very same situation, where running .jar from cmd was working fine, but double clicking did nothing.
Solution:
Open any text editor and write the command line:
java -jar Example.jar
Save the file as a .bat file.
Run this bat file to get the needed output.
Taking it one step forward, you can convert this bat file to exe file using a simple GUI tool like Bat To Exe Converter.
Now you can share your .jar as a distribution in .exe file which anyone can use just make sure you keep all the files together. (Especially the .jar and .bat file cause .bat is only a cmd prompt)(How it feels logical)
I am fairly new to development and learning a lot. Please excuse for any mistakes if committed. Suggestions are welcome.
If you use eclipse for making your java files, you can choose to export it as a runnable jar file. I did this with my programs and I can just click on the jar and it will run just like that. This will work on both windows, as well as os x.
Making a start.bat was the only thing that worked for me.
open a text document and enter. java -jar whatever yours is called .jar
save as start.bat in the same folder as the .jar file you want to execute. and then run the. bat
If you need to run the jar file by double clicking on it, you have to create it as a "Runnable JAR". you can do it simply with your IDE.
If you're using eclipse, follow these steps :
To create a new runnable JAR file in the workbench:
1.From the menu bar's File menu, select Export.
2.Expand the Java node and select Runnable JAR file. Click Next.
3.In the Opens the Runnable JAR export wizard Runnable JAR File Specification page, select a 'Java Application' launch configuration to use to create a runnable JAR.
4.In the Export destination field, either type or click Browse to select a location for the JAR file.
5.Select an appropriate library handling strategy.
Optionally, you can also create an ANT script to quickly regenerate a previously created runnable JAR file.
more information can be found on Eclipse help Page: LINK
There are many methods for running .jar file on windows. One of them is using the command prompt.
Steps :
Open command prompt(Run as administrator)
Now write "cd\" command for root directory
Type "java jar filename.jar"
Note: you can also use any third party apps like WinRAR, jarfix, etc.
Steps:
1.) search for Java SE Runtime Environment on Google: https://www.google.com/search?q=Java+SE+Runtime+Environment
2.) install the appropriate version onto your computer
For compiling:
javac -cp ".;./mysql-connector-java-5.0.8.jar;mybatis-3.0.1.jar;ibatis-2.3.0.677.jar" MainStart.java
For running:
java -cp ".;./mysql-connector-java-5.0.8.jar;mybatis-3.0.1.jar;ibatis-2.3.0.677.jar" MainStart
use .bat file:
Put your command in a .bat file. here, your command will be java -jar path\yourJarName.jar.
Something like: java -jar C:\workspace\myApplication.jar
Save it and double click on bat file to run your jar.
Actually, I faced this problem too. I got around it by making a .bat runner for my jar file.
Here is the code:
class FileHandler{
public static File create_CMD_Rnner(){
int exitCode = -1625348952;
try{
File runner = new File(Main.batName);
PrintWriter printer = new PrintWriter(runner);
printer.println("#echo off");
printer.println("title " + Main.applicationTitle);
printer.println("java -jar " + Main.jarName + " " + Main.startCode );
printer.println("PAUSE");
printer.flush();
printer.close();
return runner;
}catch(Exception e){
System.err.println("Coudln't create a runner bat \n exit code: " + exitCode);
System.exit(exitCode);
return null;
}
}
}
Then in Your Main application class do this:
public class Main{
static String jarName = "application.jar";
static String applicationTitle = "java Application";
static String startCode = "javaIsTheBest";
static String batName = "_.bat";
public static void main(String args[]) throws Exception{
if(args.length == 0 || !args[0].equals(startCode)) {
Desktop.getDesktop().open(FilesHandler.create_CMD_Rnner());
System.exit(0);
}else{
//just in case you wanted to hide the bat
deleteRunner();
// Congratulations now you are running in a cmd window ... do whatever you want
//......
System.out.println("i Am Running in CMD");
//......
Thread.sleep(84600);
}
}
public static void deleteRunner(){
File batRunner = new File(batName);
if(batRunner.exists()) batRunner.delete();
}
}
Please Note that
this code (my code) works only with a jar file, not a class file.
the jar file must have the same name as the String "jarName" is the Main class