Could not find main class...jar or manifest
<p>I am very new to programming but I am trying to learn.  I have picked up quite a bit but some concepts just seem to go over my head.  It seems like when you are learning like me and you search for a problem, you get many many different answers.  Sometimes the way the answers are worded can but confusing to a beginner.  Anyway, here is my problem.</p>

<p>I have created a very simple program that will do a basic calculation of CMU blocks in a wall.  I used the JOptionPane instead of console.  I wrote the code in notepad, then saved it as a .java file (blocktestgui.java).  I then compiled it with the command "javac blocktestgui.java" to get the "bg.class" file.  I can run the program from cmd with "java bg" and it works great.  My real problem comes with the jar file.  I created a manifest.txt file with Main-Class: bg then an empty line following.  Then I use "jar cvmf manifest.txt CMU.jar bg.class" and I get a jar file.  Then whenever I run it (in cmd or double clicking) I get "Could not find main class" error.</p>

<p>Here is what I have:</p>

<p>My java file:</p>

<pre><code>import javax.swing.JOptionPane;

class bg {
    public static void main(String[] args) {
        String firstNumber, secondNumber;
        double number1, number2, sum;

        firstNumber = JOptionPane.showInputDialog(
                "Enter wall length in decimal feet:", 
                JOptionPane.INFORMATION_MESSAGE);

        secondNumber = JOptionPane.showInputDialog(
                "Enter wall height in decimal feet:", 
                JOptionPane.INFORMATION_MESSAGE);

        number1 = Double.parseDouble(firstNumber);
        number2 = Double.parseDouble(secondNumber);

        sum = (number1 * number2) / 0.88;

        JOptionPane.showMessageDialog(null, "Total Blocks are " + sum, 
                "Results", JOptionPane.PLAIN_MESSAGE);

        System.exit(0);
    }
}
</code></pre>

<p>My jar contains my bg.class file and this is what my manifest file looks like:</p>

<pre><code>Manifest-Version: 1.0
Created-By: 1.7.0_02 (Oracle Corporation)
Main-Class: bg
</code></pre>

<p>I'm at a loss because my java file works but the jar doesn't.  Any help would be great.</p>
