Thread: Not sure how to use DecimalFormat class

Does it need an output statement or something? If so where do i put it?

package gradebook;
 
 
import javax.swing.JOptionPane;
import java.text.DecimalFormat;
public class reportcard {
public static void main (String[] args){
//A new school in the area has hired you to build a grade
//report software for them.  The school wants the software
//interaction to be as follows:
 
// Name    string
// Test1   double
// Test2   double
// Test3   double
// Test4   double
// Test5   double
// Avg   double   
// Avg= (Test1+Test2+Test3+Test4+Test5)/5.0;
//The software should also display the letter grade based on the grade scale:
//  A: 90 - 100   
//  B: 80 - 89
//  C: 70 - 79
//  D: 60 - 69
//  F: 0 - 59
//The program shall end if the average for the final grade is below zero (0)
//or higher than 100.
 
		//Intro
		System.out.print("Welcome to the gradebook.");
 
 
		String name;
		double test1;
		double test2;
		double test3;
		double test4;
		double test5;
		double average;
		String input;
 
 
		//Students Full Name  
	      name = JOptionPane.showInputDialog("Enter students " +
	                                              "name.");
 
 
	    //Decimal formatter  
	      DecimalFormat dF =
	    		  new DecimalFormat("#0.00");
 
 
 
	    // Get test grade in numerical values
 
	      input = JOptionPane.showInputDialog("Enter grade for test1");
	      test1 = Double.parseDouble(input);
 
	      input = JOptionPane.showInputDialog("Enter grade for test2");
	      test2 = Double.parseDouble(input);
 
	      input = JOptionPane.showInputDialog("Enter grade for test3");
	      test3 = Double.parseDouble(input);
 
	      input = JOptionPane.showInputDialog("Enter grade for test4");
	      test4 = Double.parseDouble(input);
 
	      input = JOptionPane.showInputDialog("Enter grade for test5");
	      test5 = Double.parseDouble(input);
 
	    //Get average score
 
	      average = (test1 + test2 + test3 + test4 + test5) / 5.0;
 
 
 
 
	   // Output the average score.
	      JOptionPane.showMessageDialog(null, 
	                                "The average is for " + average );
 
 
 
	   // Display the grade.
	      if (average < 60)
	      {
	         JOptionPane.showMessageDialog(null, "Letter Grade = F.");
	      }
	      else
	      {
	         if (average < 70)
	         {
	            JOptionPane.showMessageDialog(null, "Letter Grade = D.");
	         }
	         else
	         {
	            if (average < 80)
	            {
	               JOptionPane.showMessageDialog(null, "Letter Grade = C.");
	            }
	            else
	            {
	               if (average < 90)
	               {
	                  JOptionPane.showMessageDialog(null, "Letter Grade = B.");
	               }
	               else
	               {
	                  JOptionPane.showMessageDialog(null, "Letter Grade = A.");
	               }
	            }
	         }
 
	    //final message
	         JOptionPane.showMessageDialog(null, 
                     "The average for\n " + name + " is " + average );
 
 
	      System.exit(0);
 
 
 
}}}