How to run a JAR file

Question

I created a JAR file like this:

jar cf Predit.jar *.*

I ran this JAR file by double clicking on it (it didn\'t work). So I ran it from the

Answer 1

You need to specify a Main-Class in the jar file manifest.

Oracle's tutorial contains a complete demonstration, but here's another one from scratch. You need two files:

Test.java:

public class Test
{
    public static void main(String[] args)
    {
        System.out.println("Hello world");
    }
}

manifest.mf:

Manifest-version: 1.0
Main-Class: Test

Note that the text file must end with a new line or carriage return. The last line will not be parsed properly if it does not end with a new line or carriage return.

Then run:

javac Test.java
jar cfm test.jar manifest.mf Test.class
java -jar test.jar

Output:

Hello world