I cant get this Message dialog to appear.

import javax.swing.JOptionPane;

public class calculateMeanAndSD {

static double marks;

static double mean;

/**

* @param args

*/

public static void main(String[] args) {

// TODO Auto-generated method stub

for ( int counter = 0; counter < 10; counter++ ) {

marks = Double.parseDouble(JOptionPane.showInputDialog("En ter marks to compute Mean and Standard Deviation: "));

calculateMean();

}

}

public static void calculateMean() {

double sum = 0;

int j = 0;

sum += marks;

mean = sum / 10;

j++;

if (j == 10) {

JOptionPane.showMessageDialog(null, "The Mean of the marks entered is: "+mean);

} else {

System.out.print("");

}

}

}

=========================================

I cannot get this : " JOptionPane.showMessageDialog(null, "The Mean of the marks entered is: "+mean) " to appear.

much help would be appreciated. thanks