How do I program a JPanel such that the graphics are always visible?

JPanel graphics are not fully visible [tag:swing]

I am attempting to program an event scheduling system. I have coded a SchedulePanel class that contains a grid that I drew directly onto the panel.

public class SchedulePanel extends JPanel {

		private static final long serialVersionUID = 1L;

		static final int originX = 0;
		static final int originY = 0;
		static final int cellSide = 50;

		static final int cols = 5;
		static final int rows = 5;

		public SchedulePanel() {
			setMinimumSize(new Dimension(cols * cellSide, rows * cellSide));
			setBackground(Color.LIGHT_GRAY);
		}

		@Override
		public void paintComponent(Graphics g) {
			super.paintComponent(g);
			// this for loop draws horizontal lines that separate the rows in
			// the
			// grid
			for (int i = 0; i < rows; i++) {
				g.drawLine(originX, originY + (i * cellSide),
						originX + (cols * cellSide), originY + (i * cellSide));
			}
			// this for loop draws vertical lines that separate the columns in
			// the
			// grid
			for (int i = 0; i < cols; i++) {
				g.drawLine(originX + (i * cellSide), originY,
						originX + (i * cellSide), originY + (rows * cellSide));
			}

		}
	}

When I add this panel to the main panel containig another component I can only see the top right corner of the grid. How do I make it so that all of my graphics are visible?

public class EventSchedulerGUI extends JPanel {

	RoomPanel roomPanel;
	SchedulePanel schedulePanel;
	JList<Room> roomList;

	public EventSchedulerGUI() {
		FlowLayout layout = new FlowLayout();
		setLayout(layout);
		roomPanel = new RoomPanel();

		schedulePanel = new SchedulePanel();
		schedulePanel.setMinimumSize(new Dimension(400, 400));

		add(roomPanel);
		add(schedulePanel);

	}

Your component should be defining it's acceptable sizing hints, these are then used by the layout managers to make decisions about how best to layout your component.

As a starting point, you should override getPreferredSize, for example...

public class SchedulePanel extends JPanel {
private static final long serialVersionUID = 1L;
static final int originX = 0;
static final int originY = 0;
static final int cellSide = 50;
static final int cols = 5;
static final int rows = 5;
public SchedulePanel() {
setMinimumSize(new Dimension(cols * cellSide, rows * cellSide));
setBackground(Color.LIGHT_GRAY);
}
@Override
public Dimension getPreferredSize() {
// I generally prefer to calculate this based on the
// needs of the component and it's data, but you get the
// idea
return new Dimension(400, 400);
}
@Override
public Dimension getMinimumSize() {
return new Dimension(400, 400);
}
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
// this for loop draws horizontal lines that separate the rows in
// the
// grid
for (int i = 0; i < rows; i++) {
g.drawLine(originX, originY + (i * cellSide),
originX + (cols * cellSide), originY + (i * cellSide));
}
// this for loop draws vertical lines that separate the columns in
// the
// grid
for (int i = 0; i < cols; i++) {
g.drawLine(originX + (i * cellSide), originY,
originX + (i * cellSide), originY + (rows * cellSide));
}
}
}

Why override instead of calling setXxxSize?

Because it's the component's responsibility to make these determinations, not the callers. It's the callers responsibility to figure out how to accomodate them.

Also, you don't want someone coming along and modifying the sizing hints, that just messes everything up.