Execute .Jar File from a Java Program

Execute .jar file from a Java program

I suggest you use a ProcessBuilder and start a new JVM.

Here is something to get you started:

ProcessBuilder pb = new ProcessBuilder("/path/to/java", "-jar", "your.jar");
pb.directory(new File("preferred/working/directory"));
Process p = pb.start();

Run a jar File from java program

Using ProcessBuilder(java.lang.ProcessBuilder) will solve your problem. Syntax is as follows -

ProcessBuilder pb = new ProcessBuilder("java", "-jar", "absolute path upto jar");
Process p = pb.start();

You can redirent input/output/error to/from files as follows

File commands = new File("absolute path to inputs file");
File dirOut = new File("absolute path to outputs file");
File dirErr = new File("absolute path to error file");

dirProcess.redirectInput(commands);
dirProcess.redirectOutput(dirOut);
dirProcess.redirectError(dirErr);

How to run a .jar file from within Java program?

Use an absolute path instead of a relative path, that should prevent the path not being found if you run from any working directory. Otherwise add it to your classpath as Nizil said.

To get the current user's name, use System.getProperty("user.name") and concatenate into your path.

user = System.getProperty("user.name");
cmd = "java -jar C/Users/" + user + "/appdata/Roaming/<folder>/<file>.jar";
Runtime.getRuntime().exec(cmd);

Run class in Jar file

Use java -cp myjar.jar com.mypackage.myClass.

1. If the class is not in a package then simply java -cp myjar.jar myClass.

2. If you are not within the directory where myJar.jar is located, then you can do:

   1. On Unix or Linux platforms:

      java -cp /location_of_jar/myjar.jar com.mypackage.myClass

   2. On Windows:

      java -cp c:\location_of_jar\myjar.jar com.mypackage.myClass

Execute jar file from inside a Java program

Just run it using

Runtime.getRuntime().exec("java", "-jar", yourJarName, parameter1, parameter2);

You can pass in an arbitrary number of parameters.

As Malt described below, if you need the output of the resulting process, you can use the following code:

Process p = Runtime.getRuntime().exec("java", "-jar", yourJarName, parameter1, parameter2);
InputStream is = p.getInputStream();

Note that you call InputStream to get the output of the process, because you are reading from the stream, so it is an input with regards to your program, and an output with regards to the subprocess.

Run a JAR file from the command line and specify classpath

When you specify -jar then the -cp parameter will be ignored.

From the documentation:

When you use this option, the JAR file is the source of all user classes, and other user class path settings are ignored.

You also cannot "include" needed jar files into another jar file (you would need to extract their contents and put the .class files into your jar file)

You have two options:

1. include all jar files from the lib directory into the manifest (you can use relative paths there)
2. Specify everything (including your jar) on the commandline using -cp:
   
   java -cp MyJar.jar:lib/* com.somepackage.subpackage.Main

Running JAR file on Windows

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

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