// RepaintandValidateGrades.java
// Counting letter grades

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;

public class RepaintandValidateGrades extends JApplet
			implements ActionListener {

	JLabel prompt;		// label for text field input
	JTextField input;					// text field to enter grades
	JLabel correction_prompt;			// label for text field correction_display
	JTextField correction_display;    	// text field to show erroneous grades
	JPanel inter;						// panel for interaction with the user
	JPanel message;						// panel for writing grades status

	boolean correction_present;

	int aCount = 0, bCount = 0, cCount = 0, dCount = 0, fCount = 0;

	Container c;

	public void init()
	{

		c = getContentPane();
		c.setLayout ( new GridLayout (2,1, 10, 10) );

		inter = new JPanel();
		inter.setLayout (new GridLayout(1,2));
		
		prompt = new JLabel( "Enter grade" );
		input = new JTextField( 2 );
		input.addActionListener( this );
		inter.add( prompt );
		inter.add( input );

		message = new JPanel();

		c.add( inter );
		c.add( message );
		
		correction_present = false;
		
	}


	public void paint( Graphics g )
	{  
			g.drawString( "Totals for each letter grade:", 25, 180 );
			g.drawString( "A: " + aCount, 25, 195 );
			g.drawString( "B: " + bCount, 25, 210 );
			g.drawString( "C: " + cCount, 25, 225 );
			g.drawString( "D: " + dCount, 25, 240 );
			g.drawString( "F: " + fCount, 25, 255 );
	}


	public void actionPerformed( ActionEvent e )
	{
		String val = e.getActionCommand();   
		char grade = val.charAt( 0 );  
		showStatus( "" );       // clear status bar area
		input.setText( "" );    // clear input text field

		// removing correction components
		if ( correction_present ) {
			inter.remove (correction_prompt);
			inter.remove (correction_display);
			inter.setLayout (new GridLayout(1,2));
			correction_present = false;
		};
 
		switch ( grade ) {      
			case 'A': case 'a':  // Grade was uppercase A
				++aCount;         // or lowercase a.
				break;
			case 'B': case 'b':  // Grade was uppercase B
				++bCount;         // or lowercase b.
				break;
			case 'C': case 'c':  // Grade was uppercase C
				++cCount;         // or lowercase c.
				break;
			case 'D': case 'd':  // Grade was uppercase D
				++dCount;         // or lowercase d.
				break;
			case 'F': case 'f':  // Grade was uppercase F
				++fCount;         // or lowercase f.
				break;
			default:             // catch all other characters
				showStatus( "Incorrect grade. Enter new grade." );
				correction_prompt = new JLabel( "You entered an incorrect grade:" );
				correction_display = new JTextField( new Character(grade).toString() );
				
				inter.setLayout(new GridLayout(2,2));
				inter.add (correction_prompt);
				inter.add (correction_display);
				
				validate();   // show new GUIs

				correction_present = true;			

				break;
			}

		c.repaint(); 	repaint();	// display summary of results

	}

}