.jar executable

Question

Hi!
I have been trying to create an executable jar, but I only get the message "Could not find main class. Program will exit".
This is what I have done!
1. I created a java file that prints "Hello". This is the one
import java.io.*;
public class Test{
     public static void main (String [] args) throws IOException{
          System.out.println("Hello");
2. I compile it
3. I make a jar of the two files. The java file and the class file. To do so I type the following in the command window:
jar cf temp.jar Test.java Test.class
4. I create a manifest file and name it Manifest.txt. It contains the text:
Main-Class: temp.Test
5. I now create the (expected) executable jar file. Typing the following in the command window:
jar cfm MyJar.jar Manifest.txt temp.jar
And when I now try to double click the MyJar.jar I only get "Could not find main class. Program will exit". WHAT am I doing wrong??? Please help!
/Jonathan

Answer 1

jonfra wrote:
Hi!
I have been trying to create an executable jar, but I only get the message "Could not find main class. Program will exit".
This is what I have done!
1. I created a java file that prints "Hello". This is the one
import java.io.*;
public class Test{
     public static void main (String [] args) throws IOException{
          System.out.println("Hello");
First off, you know that you don't need to import java.io or throw IOException for what you have here, okay?
2. I compile it
How did you compile it? As >javac Test.java? ... or >javac -classpath . Test.java? ... or ?
3. I make a jar of the two files. The java file and the class file. To do so I type the following in the command window:
Not wrong to do it, but why do you want the source code in the jar file?
jar cf temp.jar Test.java Test.class
I'd skip this step '3' and move on to step 4.
4. I create a manifest file and name it Manifest.txt. It contains the text:
Main-Class: temp.TestMake sure that you have an EOL character at the end of Manifest.txt - like so:
Main-Class: temp.Test
- this line needs to be blank -
Also, why the temp. ? your class - as Mapleshaft alluded to, does not have a package statement.
>
5. I now create the (expected) executable jar file. Typing the following in the command window:
jar cfm MyJar.jar Manifest.txt temp.jar
After skipping step 3 entirely, jar as:
jar cmf0 Manifest.txt MyJar.jar Test.class
And when I now try to double click the MyJar.jar I only get "Could not find main class. Program will exit". WHAT am I doing wrong??? Please help!
/JonathanLastly, this is not a GUI, so double clicking on it won't do anything anyway. You'll need to run it from the command line as >java -jar MyJar.jar