Problem with saving a state in calendar program.

I have attached a calendar program currently being used in a bigger program. However there is a problem with saving on the component picked. Currently it changes the background colour when the button is clicked but when another square is clicked on then the background colour changes back to normal is there anyway to keep the background colour when another square is clicked on.

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Component;
import java.awt.Container;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Calendar;
import java.util.GregorianCalendar;

import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.JTextField;

public class Cal extends JPanel implements ActionListener {
  // The currently-interesting year (not modulo 1900!) 
  protected int yy;
  // Currently-interesting month and day 
  protected int mm, dd;
  // The buttons to be displayed 
  protected JButton labs[][];
  // The number of day squares to leave blank at the start of this month 
  protected int leadGap = 0;
  // A Calendar object used throughout 
  Calendar calendar = new GregorianCalendar();
  // Today's year 
  protected final int thisYear = calendar.get(Calendar.YEAR);
  // Today's month 
  protected final int thisMonth = calendar.get(Calendar.MONTH);
  // One of the buttons. We just keep its reference for getBackground()
  private JButton b0;
  // The month choice 
  private JComboBox monthChoice;
  // The year choice 
  private JComboBox yearChoice;
  // Button to add item to date
  private JButton add;
  // Text associated with item 
  private  JTextField itemText = new JTextField(80);
  // Type of item to be added to date
  String [] typeChoiceCB = { "Meeting", "Task", "Deadline", "Entry" };
  private JComboBox typeChoice;
  // Text area for items to be displayed
  private meetings lnkmeetings;
  private entries lnkentries;
    
  public Cal(meetings meet, entries entry){
	  lnkmeetings = meet;
	  lnkentries = entry;
  }
   //Construct a Cal, starting with today.
  Cal() {
    super();
    setYYMMDD(calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH), calendar.get(Calendar.DAY_OF_MONTH));
    buildGUI();
    recompute();	
  }

//Construct a Cal, given the leading days and the total days @exception IllegalArgumentException If year out of range
  
  Cal(int year, int month, int today) {
    super();
    setYYMMDD(year, month, today);
    buildGUI();
    recompute();
  }

private void setYYMMDD(int year, int month, int today) {
    yy = year;
    mm = month;
    dd = today;
  }

String[] months = { "January", "February", "March", "April", "May", "June",
      "July", "August", "September", "October", "November", "December" };

// Builds the GUI. Assumes that setYYMMDD has been called.
  private void buildGUI() {
    getAccessibleContext().setAccessibleDescription("Calendar not accessible yet.");
    setBorder(BorderFactory.createEtchedBorder());
    setLayout(new BorderLayout());
    JPanel tp = new JPanel();
    add  = new JButton("Add to Date"); 
    tp.add(add);
    add.addActionListener(this);
    tp.add(itemText);
    tp.add(typeChoice = new JComboBox(typeChoiceCB));
    tp.add(monthChoice = new JComboBox());
    for (int i = 0; i < months.length; i++)
      monthChoice.addItem(months[i]);
      monthChoice.setSelectedItem(months[mm]);
      monthChoice.addActionListener(new ActionListener() {
    	  
        public void actionPerformed(ActionEvent ae) {
            int i = monthChoice.getSelectedIndex();
            if (i >= 0) {
                mm = i;
                recompute();
            }
        }
      }
    );
      
    monthChoice.getAccessibleContext().setAccessibleName("Months");
    monthChoice.getAccessibleContext().setAccessibleDescription("Choose a month of the year");

tp.add(yearChoice = new JComboBox());
    yearChoice.setEditable(true);
    for (int i = yy + 0; i < yy + 1; i++)
      yearChoice.addItem(Integer.toString(i));
      yearChoice.setSelectedItem(Integer.toString(yy));
      yearChoice.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent ae) {
            int i = yearChoice.getSelectedIndex();
            if (i >= 0) {
                yy = Integer.parseInt(yearChoice.getSelectedItem().toString());
                recompute();
            }
      }
    }
    );
   
      
    add(BorderLayout.CENTER, tp);
    JPanel bp = new JPanel();
    bp.setLayout(new GridLayout(7, 7));
    labs = new JButton[6][7]; // first row is days

bp.add(b0 = new JButton("S"));
    bp.add(new JButton("M"));
    bp.add(new JButton("T"));
    bp.add(new JButton("W"));
    bp.add(new JButton("T"));
    bp.add(new JButton("F"));
    bp.add(new JButton("S"));

ActionListener dateSetter = new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        String num = e.getActionCommand();
        if (!num.equals("")) {
          // set the current day highlighted
          setDayActive(Integer.parseInt(num));
        }
      }
    };

// Construct all the buttons, and add them.
    for (int i = 0; i < 6; i++)
      for (int j = 0; j < 7; j++) {
        bp.add(labs[i][j] = new JButton(""));
        labs[i][j].addActionListener(dateSetter);
      }

add(BorderLayout.SOUTH, bp);
  }

public final static int dom[] = { 31, 28, 31, 30, // jan feb mar apr 
  31, 30, 31, 31, // may jun jul aug 
  30, 31, 30, 31 // sep oct nov dec 
  };

// Compute which days to put where, in the Cal panel 
  protected void recompute() {
    if (mm < 0 || mm > 11)throw new IllegalArgumentException("Month " + mm + " bad, must be 0-11");
    clearDayActive();
    calendar = new GregorianCalendar(yy, mm, dd);

// Compute how much to leave before the first.
    // getDay() returns 0 for Sunday, which is just right.
    leadGap = new GregorianCalendar(yy, mm, 1).get(Calendar.DAY_OF_WEEK) - 1;
    // System.out.println("leadGap = " + leadGap);

int daysInMonth = dom[mm];
    if (isLeap(calendar.get(Calendar.YEAR)) && mm == 1)
      ++daysInMonth;

// Blank out the labels before 1st day of month
    for (int i = 0; i < leadGap; i++) {
      labs[0][i].setText("");
    }

// Fill in numbers for the day of month.
    for (int i = 1; i <= daysInMonth; i++) {
      JButton b = labs[(leadGap + i - 1) / 7][(leadGap + i - 1) % 7];
      b.setText(Integer.toString(i));
    }

// 7 days/week * up to 6 rows
    for (int i = leadGap + 0 + daysInMonth; i < 6 * 7; i++) {
      labs[(i) / 7][(i) % 7].setText("");
    }

// Shade current day, only if current month
    if (thisYear == yy && mm == thisMonth)
      setDayActive(dd); // shade the box for today

// Say we need to be drawn on the screen
    repaint();
  }

/*
   * isLeap() returns true if the given year is a Leap Year.
   * "a year is a leap year if it is divisible by 4 but not by 100, except
   * that years divisible by 400 *are* leap years." -- Kernighan & Ritchie,
   * _The C Programming Language_, p 37.
   */
  
  public boolean isLeap(int year) {
    if (year % 4 == 0 && year % 100 != 0 || year % 400 == 0)
      return true;
    return false;
  }

// Set the year, month, and day 
  public void setDate(int yy, int mm, int dd) {
    this.yy = yy;
    this.mm = mm; // starts at 0, like Date
    this.dd = dd;
    recompute();
  }

// Unset any previously highlighted day 
  private void clearDayActive() {
    JButton b;

// First un-shade the previously-selected square, if any
    if (activeDay > 0) {
      b = labs[(leadGap + activeDay - 1) / 7][(leadGap + activeDay - 1) % 7];
      b.setBackground(b0.getBackground());
      b.repaint();
      activeDay = -1;
    }
  }

private int activeDay = -1;

// Set just the day, on the current month 
  public void setDayActive(int newDay) {

clearDayActive();

// Set the new one
    if (newDay <= 0)
      dd = new GregorianCalendar().get(Calendar.DAY_OF_MONTH);
    else
      dd = newDay;
    // Now shade the correct square
    Component square = labs[(leadGap + newDay - 1) / 7][(leadGap + newDay - 1) % 7];
    square.setBackground(Color.blue);
    square.repaint();
    activeDay = newDay;
  }
  
  public void setTaskDay(int newDay){
	    Component square = labs[(leadGap + newDay - 1) / 7][(leadGap + newDay - 1) % 7];
	    // Component square = labs[(leadGap + newDay) / 7][(leadGap + newDay) % 7];
	    square.setBackground(Color.yellow);
	    square.repaint();
	    
  }
  public void setMeetingDay(int newDay){
	    Component square = labs[(leadGap + newDay - 1) / 7][(leadGap + newDay - 1) % 7];
	    square.setBackground(Color.black);
	    square.repaint();
  }

public void setDeadlineDay(int newDay){
	    Component square = labs[(leadGap + newDay - 1) / 7][(leadGap + newDay - 1) % 7];
	    square.setBackground(Color.red);
	    square.repaint();
  }
  
  public void setEntryDay(int newDay){
	    Component square = labs[(leadGap + newDay - 1) / 7][(leadGap + newDay - 1) % 7];
	    square.setBackground(Color.green);
	    square.repaint();
  }
  
  public void actionPerformed(ActionEvent e) {
	if(e.getSource() == add){
		if(itemText.getText().trim().length() != 0){
			if(typeChoice.getSelectedItem().equals("Task")){
				System.out.println("Add task works.");
				setTaskDay(activeDay);	
			}
			else if(typeChoice.getSelectedItem().equals("Meeting")){
				meetings.addMeeting(dd, mm, yy, itemText.getText());
				System.out.println("Add meeting works " + yy + mm + dd);
				setMeetingDay(activeDay);
			}
			else if (typeChoice.getSelectedItem().equals("Entry")){
				entries.addEntry(dd, mm, yy, itemText.getText());
				System.out.println("Add entry works " + yy + mm + dd);
				setEntryDay(activeDay);
			}
			else if (typeChoice.getSelectedItem().equals("Deadline")){
				System.out.println("Add deadline works.");
				setDeadlineDay(activeDay);
			}
		}
	}
  }
}

311 lines and it doesn't compile?

you expect us to read all that, and build a calendar in our head, then click imaginary buttons,
and see all sorts of colors changing.

you try it first, let us know how it goes.

Sorry there was some stuff linked to other parts of the program.
Here is the main

Here is the calendar:

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Component;
import java.awt.Container;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Calendar;
import java.util.GregorianCalendar;

import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.JTextField;

public class Cal extends JPanel implements ActionListener {
  // The currently-interesting year (not modulo 1900!) 
  protected int yy;
  // Currently-interesting month and day 
  protected int mm, dd;
  // The buttons to be displayed 
  protected JButton labs[][];
  // The number of day squares to leave blank at the start of this month 
  protected int leadGap = 0;
  // A Calendar object used throughout 
  Calendar calendar = new GregorianCalendar();
  // Today's year 
  protected final int thisYear = calendar.get(Calendar.YEAR);
  // Today's month 
  protected final int thisMonth = calendar.get(Calendar.MONTH);
  // One of the buttons. We just keep its reference for getBackground()
  private JButton b0;
  // The month choice 
  private JComboBox monthChoice;
  // The year choice 
  private JComboBox yearChoice;
  // Button to add item to date
  private JButton add;
  // Text associated with item 
  private  JTextField itemText = new JTextField(80);
  // Type of item to be added to date
  String [] typeChoiceCB = { "Meeting", "Task", "Deadline", "Entry" };
  private JComboBox typeChoice;
  // Text area for items to be displayed
    
  
   //Construct a Cal, starting with today.
  Cal() {
    super();
    setYYMMDD(calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH), calendar.get(Calendar.DAY_OF_MONTH));
    buildGUI();
    recompute();	
  }