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Thread: Gregorian Calendar - Problems

  1. #1
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    Default Gregorian Calendar - Problems

    Hello... I am working on a project for my intro to Java class and I am stuck. We have to design a functioning calendar, and I am using GregorianCalendar to pull my Current Day, Month, Year, etc. For some reason the month is off by 1 month though (6 instead of 7). Also, I would much rather return the name of the month (July instead of 6) but I can't seem to figure it out. Lastly, I can't seem to get the number of days to fall on the buttons in the proper place. I know I'm asking a lot, but this assignment is really hard, and I'm trying to get as much help as I can because I am stuck...

    Here is my code...

    public class Calendar extends JFrame {
     
    	public Calendar() {
    		this.setSize(640,480);
    		this.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
    		this.setVisible(true);
    		this.setTitle("Calendar");
     
    		JPanel borderPanel = new JPanel();
    		borderPanel.setLayout(new BorderLayout());
    		getContentPane().add(borderPanel);
     
    		// Initialize GregorianCalendar
    		GregorianCalendar cal = new GregorianCalendar();
    		int currYear = cal.get(GregorianCalendar.YEAR);
    		int currDOM = cal.get(GregorianCalendar.DAY_OF_MONTH);
    		int currMnth = cal.get(GregorianCalendar.MONTH);
    		int nod, som;
    		nod = cal.getActualMaximum(GregorianCalendar.DAY_OF_MONTH); //Number of Days
    		som = cal.get(GregorianCalendar.DAY_OF_WEEK); // Start of the Month
     
    		// Button Layout
    		final int ROWS = 6;
    		final int COLS = 7;
    		JButton[][] days;
    		JPanel calendar = new JPanel();
    		calendar.setLayout(new GridLayout(6,7));
    		days = new JButton[ROWS][COLS];
    		for(int row = 0; row < ROWS; row++) {
    			for(int col = 0; col < COLS; col++) {
    				days[row][col] = new JButton("");
    				calendar.add(days[row][col]);
    			}
    		}
     
    		// Add Some Number to the Buttons
    		int[] tableMonth = {31,28,31,30,31,30,31,31,30,31,30,31};
    		int startDay = som;
    		int daysInMonth = tableMonth[currMnth];
    		for(int i = 0; i < daysInMonth; i++){
    			days[(startDay + i)/7][(startDay + i) % 7].setText("" + (i + 1));
    		}
    		borderPanel.add(calendar, BorderLayout.CENTER);
     
    		// North Panel - Current Month / Prev & Next Button
    		JPanel month = new JPanel();	
    		month.add(new JButton("Previous"));
    		month.add(new JButton("The Month is: " + currMnth));
    		month.add(new JButton("Next"));
    		borderPanel.add(month, BorderLayout.NORTH);
     
    		// West Panel - Current Date
    		JPanel year = new JPanel();
    		year.add(new JButton("The Year is: " + currYear ));
    		borderPanel.add(year, BorderLayout.SOUTH);
     
    		// South Panel - Current Year
    		JPanel today = new JPanel();
    		today.add(new JButton("Today is: " + currMnth + "/" + currDOM + "/" + currYear));
    		borderPanel.add(today, BorderLayout.WEST);
     
    	}
    	public static void main(String[] args) {
    		new Calendar();
    	}
    }

    Thank you so much for any help!


  2. #2
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    Default Re: Gregorian Calendar - Problems

    As for the name of the month, a simple switch statement should do it

    As for the month thing, I'm getting that too.

    I think that it is supposed to return 6.

    Constant Field Values (Java Platform SE 7 )

    January is 0.

    int month = cal.get(GregorianCalendar.MONTH);

    String month2 = "";

    switch (month)
    {

    case 0:
    month2 = "January";
    break;
    case 1:
    month2 = "February";
    break;
    case 2:
    month2 = "March";
    break;
    etc
    }

    Quote Originally Posted by BobDole6395
    Lastly, I can't seem to get the number of days to fall on the buttons in the proper place.
    What do you mean exactly by that?
    Last edited by GoodbyeWorld; July 3rd, 2012 at 12:14 AM.

  3. #3
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    Default Re: Gregorian Calendar - Problems

    What do you mean exactly by that?
    The days of the month don't fall on the proper blocks. For example, July first was a Sunday, but it is falling on Tuesday. I think something is wrong with my for loop, but I can't see it.

  4. #4
    Member GoodbyeWorld's Avatar
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    Default Re: Gregorian Calendar - Problems

    cal.get(GregorianCalendar.DAY_OF_WEEK);

    is returning 3 for today.


    I assume you meant to get the start day of the month.

    Maybe you should use

    cal.get(GregorianCalendar.DAY_OF_WEEK_IN_MONTH);

    for figuring out the day_of_week/day_in_month correspondence.



    public static final int DAY_OF_WEEK_IN_MONTH
    Last edited by GoodbyeWorld; July 3rd, 2012 at 12:57 AM.

  5. #5
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    Default Re: Gregorian Calendar - Problems

    Thanks so much! I got the month to return with July instead of 6 thanks to the switch. I am not quite getting the calendar to fill in properly, I tried the DAY_OF_WEEK_IN_MONTH but it didn't help, or I did it wrong. I swear this stuff is way to hard for a 100 level intro to Java, but I gotta get it done, lol... Thanks again!

  6. #6
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    Default Re: Gregorian Calendar - Problems

    Okay... so I've got everything working in terms of populating the buttons with the calendar. I am trying to setup the ActionListener for the prev and next buttons and I can't get it to work... well, its working, if I hit the button and do a println it updates the month +1 or -1 in my console, but the calendar itself is not refreshing. So, any ideas would be greatly appreciated!!!

    public class Calendar extends JFrame {
     
    	static JButton btnNext, btnPrev;
    	static int currYear, currDOM, currentMonth;
     
    	public Calendar() {
    		this.setSize(800,600);
    		this.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
    		this.setVisible(true);
    		this.setTitle("Calendar");
     
     
    		JPanel borderPanel = new JPanel();
    		borderPanel.setLayout(new BorderLayout());
    		getContentPane().add(borderPanel);
     
    		// Initialize GregorianCalendar
    		GregorianCalendar cal = new GregorianCalendar();
    		int currYear = cal.get(GregorianCalendar.YEAR);
    		int currDOM = cal.get(GregorianCalendar.DAY_OF_MONTH);
    		int currMnth = cal.get(GregorianCalendar.MONTH);
    		currentMonth = currMnth;
    		String StringMnth = "";
    			switch(currMnth) {
    			case 0: StringMnth = "January"; break;
    			case 1: StringMnth = "February"; break;
    			case 2: StringMnth = "March"; break;
    			case 3: StringMnth = "April"; break;
    			case 4: StringMnth = "May"; break;
    			case 5: StringMnth = "June"; break;
    			case 6: StringMnth = "July"; break;
    			case 7: StringMnth = "August"; break;
    			case 8: StringMnth = "September"; break;
    			case 9: StringMnth = "October"; break;
    			case 10: StringMnth = "November"; break;
    			case 11: StringMnth = "December"; break;
    		}
    		int nod, som;
    		cal.set(GregorianCalendar.DATE, 1);
    		nod = cal.getActualMaximum(GregorianCalendar.DAY_OF_MONTH); //Number of Days
    		som = (cal.get(GregorianCalendar.DAY_OF_WEEK) - GregorianCalendar.SUNDAY + 7)%7; // Start of the Month
     
    		// Button Layout
    		final int ROWS = 6;
    		final int COLS = 7;
    		JButton[][] days;
    		JPanel calendar = new JPanel();
    		calendar.setLayout(new GridLayout(6,7));
    		days = new JButton[ROWS][COLS];
    		for(int row = 0; row < ROWS; row++) {
    			for(int col = 0; col < COLS; col++) {
    				days[row][col] = new JButton("");
    				calendar.add(days[row][col]);
    			}
    		}
     
    		// Add Some Number to the Buttons
    		int[] tableMonth = {31,28,31,30,31,30,31,31,30,31,30,31};
    		int startDay = som;
    		int daysInMonth = tableMonth[currMnth];
    		for(int i = 0; i < daysInMonth; i++){
    			days[(startDay + i)/7][(startDay + i) % 7].setText("" + (i + 1));
    		}
    		borderPanel.add(calendar, BorderLayout.CENTER);
     
    		// North Panel - Current Month / Prev & Next Button
    		btnNext = new JButton(">>");
    		btnPrev = new JButton("<<");
    		JPanel month = new JPanel();	
    		month.add(btnPrev);
    		month.add(new JLabel(StringMnth));
    		month.add(btnNext);
    		borderPanel.add(month, BorderLayout.NORTH);
     
    		//Listeners
    		btnPrev.addActionListener(new btnPrev_Action());
    		btnNext.addActionListener(new btnNext_Action());
     
    		// West Panel - Current Date
    		JPanel year = new JPanel();
    		year.add(new JButton("The Year is: " + currYear ));
    		borderPanel.add(year, BorderLayout.SOUTH);
     
    		// South Panel - Current Year
    		JPanel today = new JPanel();
    		today.add(new JButton("Today is: " + StringMnth + " " + currDOM + ", " + currYear));
    		borderPanel.add(today, BorderLayout.WEST);
     
    	}
     
    	static class btnNext_Action implements ActionListener{
    		public void actionPerformed (ActionEvent e){
    			currentMonth += 1;
    			System.out.print(currentMonth);
    		}
    	}
     
    	static class btnPrev_Action implements ActionListener{
    		public void actionPerformed (ActionEvent e){
    			currentMonth -= 1;
    			System.out.print(currentMonth);
    		}
    	}
    	public static void main(String[] args) {
    		new Calendar();
    	}
    }

  7. #7
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    Default Re: Gregorian Calendar - Problems

    Anyone? I am stuck on the ActionListener... I can't seem to figure this out and it's driving me nuts!

  8. #8
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    Default Re: Gregorian Calendar - Problems

    Changing currentMonth will not trigger the GUI to recreate the calendar. You will need to figure out a way to recreate the GUI when you change the month (perhaps by moving some of the GUI creation code into a method that you can call from the actionListener).
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