How can I execute jar file in UNIX-like using this command line: java -jar mysolution.jar < inputfile.txt

Question

I tried to use the below command line to execute jar file, but whatever follow the "<" had been omit. I have tried to find the solution on the internet, but no luck. Can you please help me?

How can I execute jar file in UNIX-like using this command line:

java -jar mysolution.jar < inputfile.txt

Thanks

Answer 1

Assuming mysolution.jar contains a main method like this:

public static void main(String[] args) {
    ...
}

Anything after mysolution.jar in your command will be filled into the args String array. So if you run this:

java -jar mysolution.jar inputfile.txt

Then in your main method args will be an array of length 1, whose only value is the String inputfile.txt .

You will then have to write the code that opens that file and does something with it.

Your original approach would replace stdin with a file stream coming from that file. To work with the file that way you would have to use a Scanner

Here's another question/answer with some details on reading a file via stdin