How to run jar file from inside a class?

Question

I want to run a program using the following commands

java Main -host arg1 arg2

However I have faced some troble as I had made the project in separate packages. So I get a jar file and cannot run the main from the above keywords. I have to call the jar file thus from the command line.

java -jar Main.jar arg1 arg2

However I do not want that as it goes against my specification.

Can you help me please?

SPECIFICATION

A text-only application is all that is required. It must be networked and run as either a host (server) or a client from the command line using the commands:

java BankApp -host PORT
java BankApp -client MACHINE PORT

to start as host or client respectively. For example, if you know the host is running on aloha at port 8888 you would connect with:

java BankApp -client aloha 8888

what I need to do to run is as follows.

java -jar C:\Users\UniversityofBristol\Desktop\BankApp\BankApp\dist BankApp.jar arg1 arg2

public class BankApp {

public static void main(String[] args) throws IOException, ClassNotFoundException {


    String current = new java.io.File(".").getCanonicalPath();
    current = "java -jar " + current + "\\dist";
    current = "\"" + current + "\"";
    current = current + " BankApp.jar";
    System.out.println("Current dir:" + current);

    // Run a java app in a separate system process
    Process proc = Runtime.getRuntime().exec(current);
    // Then retreive the process output
    InputStream in = proc.getInputStream();
    InputStream err = proc.getErrorStream();

}

}

@AdityaSaxena - have a look at the [ProcessBuilder](http://docs.oracle.com/javase/7/docs/api/java/lang/ProcessBuilder.html), the javaDoc has a good example on how to start processes. Note, that the executable and the arguments are all in separate Strings! — Andreas Dolk, Jul 06 '13 at 14:45

score 1 · Answer 1 · edited May 23 '17 at 10:25

1

See this answer if you want to run the .jar in a separate process.

Otherwise I think you can just add it to your project (look under project properties in whatever IDE you are using) and use it as any other library.

edited May 23 '17 at 10:25

Community

1
1

answered Jul 06 '13 at 13:55

Marconius

683
1
5
13

score 0 · Answer 2 · answered Jul 06 '13 at 13:53

0

Just put your jar on the classpath. You could break the spec a little bit, by saying:

java -cp bankapp.jar BankApp arg1 arg2

or set the $CLASSPATH environment variable (which is ugly and I never really do it outside scripts but it works):

export CLASSPATH=path/to/your/jar
java BankApp arg1 arg2

Spoiler

Setting the classpath

answered Jul 06 '13 at 13:53

Andreas Dolk

113,398
19
180
268

Thanks! But I have to add no aditional arguments. I tried creating a dummy BankApp Class and tried to call the jarfile from it. – Aditya Saxena Jul 06 '13 at 13:57
-cp bankapp.jar is not allowed. I have seen that. It has to be java BankApp -host arg1 arg2... – Aditya Saxena Jul 06 '13 at 14:00
Then use the second approach (define the CLASSPATH variable). Is your spec really *that* strict that you aren't allowed to add java vm options? – Andreas Dolk Jul 06 '13 at 14:00
Trying that ! thanks if it works will send a message in some time. Need to read it. Have never done before. – Aditya Saxena Jul 06 '13 at 14:04
Exception in thread "main" java.lang.IllegalArgumentException: Executable name has embedded quote, split the arguments – Aditya Saxena Jul 06 '13 at 14:23
@AdityaSaxena - Could you edit your question and paste the code that causes this exception? – Andreas Dolk Jul 06 '13 at 14:26

How to run jar file from inside a class?

2 Answers2