JLabel not Showing

[sirlink99]

I have this part of my code. I have a JLabel and a JButton that are in a panel. The I place that panel into another panel that has a border layout and I set the panel containing the label and button to be "NORTH", but the JLabel does not show. When I romove the button it does. Why? How can I fix this? Thanks. Here is my code:

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


public class ISU implements ActionListener{

	JFrame mainFrame;
	JLabel descriptionLabel;
	public JLabel pictureLabel;
	JButton launchApplication;
	public ISU (){
		mainFrame = new JFrame ("Physics ISU Library");
		JPanel mainPane = new JPanel ();
		JPanel descriptPane = new JPanel ();
		JPanel picPane = new JPanel ();
		
		pictureLabel = new JLabel ();
		
		JMenuBar menuBar = new JMenuBar ();
		JMenu motionItem = new JMenu ("Motion");
		
		JMenu energyItem = new JMenu ("Energy");
		
		JMenu soundItem = new JMenu ("Sound");
		JMenuItem transverseWave = new JMenuItem ("Transverse Wave"); transverseWave.setActionCommand("transverseWave");transverseWave.addActionListener(this);
		JMenuItem longitudinalWave = new JMenuItem ("Longitudinal Wave"); longitudinalWave.setActionCommand("longitudinalWave"); longitudinalWave.addActionListener (this);
		JMenuItem dopplerEffect = new JMenuItem ("Doppler Effect"); dopplerEffect.setActionCommand("dopplerEffect"); dopplerEffect.addActionListener(this);
		
		JMenu electricityItem = new JMenu ("Electricity");
		
		JMenu magnetismItem = new JMenu ("Magnetism");
		
		
		soundItem.add(transverseWave); soundItem.add(longitudinalWave); soundItem.add(dopplerEffect);
		
		menuBar.add(motionItem); menuBar.add(energyItem); menuBar.add(soundItem); menuBar.add(electricityItem); menuBar.add(magnetismItem);
		mainFrame.add("North",menuBar);
		
		descriptPane.setLayout (new BorderLayout ());
		
		
		descriptionLabel = new JLabel ("This is the program that demonstrates how a blank works.");
		
		launchApplication = new JButton ("Launch");
		
		descriptPane.add(descriptionLabel);
		descriptPane.add (launchApplication);
		
		mainPane.setLayout(new BorderLayout ());
		mainPane.add (descriptPane, BorderLayout.NORTH);
		
		mainPane.add(picPane, BorderLayout.CENTER);
		
		mainFrame.add (mainPane);
		
		mainFrame.setSize (600,500);
		mainFrame.setVisible(true);
	}
	
	
	
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		ISU isu = new ISU ();
	}
}

[hfx642]

Try...

JPanel Top_Panel = new JPanel (new FlowLayout ());
Top_Panel.add (descriptionLabel);
Top_Panel.add (launchApplication);
descriptPane.add (Top_Panel, BorderLayout.NORTH);

[sirlink99]

Thanks. I realized that I had the border layout code still added to the top pane. Thanks for your help.

[sirlink99]

I am having trouble printing a sine wave (transverse wave) a wave that kind of looks like this ~

except wounded. you can just goolge it here i will do it for you. here

that is what it is supposed to look like. One cycle, but my program gives me more and I dont know why. Thanks for the help

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


public class TransverseWaveProgram extends JPanel implements ActionListener{

		
		int [] xaxis = new int [360];
		int [] yaxis = new int [360];
	
		public void TransverseWave (){
			for (int i = 0; i < 360; i++){
				xaxis[i] = i;
				yaxis[i] = ((int)(Math.round( (Math.sin(i) * - 1) * 100)));
				yaxis[i] = yaxis[i] + 300;
			}
			
			repaint();
			
		}
		
		
		
		
		
		public void paintComponent (Graphics g){
			super.paintComponent (g);
			
			for (int i = 0; i < 360; i++){
				
				g.fillPolygon (xaxis,yaxis, 360);
				
			}
			
			
		}

		
		public void actionPerformed(ActionEvent arg0) {
			// TODO Auto-generated method stub
			
		}
		
		
		
		
	
}

if you are wondering this is the basic equation

y = sinx

again. Thanks for the help.

[Topi Ojala]

Math.sin function wants the angle in radians, not degrees.

360 degrees would be 2*pi radians.

[sirlink99]

ok thanks. I didn't know it was radians

[sirlink99]

is there an easier way to graph it? I need it to stretch over a normal distance. Ho would I accomplish this? is there a graphing option that uses mathematical terms to graph a function at a certain point and allows you to vary it throughout the program? Also sometimes when I use my code it glitches and it flashes the drawing and then disappears. What could be the cause of this? Thanks.

[Ezzaral]

You just need to subdivide the period of your function over a certain number of pixels and build a Path2D from the (x,y) value pairs.

Here are some fragments of pseudocode to get you started:

periodValueOfPixel = x/graphWidth*periodOfFunction

Looping over an x range you calc

y = Math.sin(periodValueOfPixel)*graphHeight

and connect your path to the next point

path.lineTo(x,y)

When your path is complete use Graphics2D.draw(Shape) to render it.