Solve Java JLabel Problem: Display Output on mainPanel

[clook]

i am trying to display the output in a jlabel. I have created individual jlabels for the package ID, weight, and shipping cost and tried to display them with the mainPanel:

import javax.swing.*;

import java.awt.event.*;
public class shippingCharge extends JFrame implements ActionListener
{

	//objects and data types created here
	JPanel mainPanel = new JPanel();
	JTextField packageIdentificationTextField = new JTextField(6);
	JTextField poundsTextField = new JTextField(10);
	JTextField ouncesTextField = new JTextField(10);
	JButton displayButton = new JButton("Calculate  ");
	
	
	//Variables
	String packageIdentificationString;
	double poundDouble, ouncesDouble, poundToOunceOuncesDouble, shippingCostDouble;	public static void main(String[] args)
	{
		shippingCharge shippingTotal = new shippingCharge();
	}
		
	public shippingCharge()
	{
		designFrame();
		setSize(500,500);
		setVisible(true);
		
	}
	
	public void designFrame()
	{
		mainPanel.add(new JLabel("Package ID"));
		mainPanel.add(packageIdentificationTextField);
		mainPanel.add(new JLabel("Pounds"));
		mainPanel.add(poundsTextField);
		mainPanel.add(new JLabel("Ounces"));
		mainPanel.add(ouncesTextField);
		mainPanel.add(displayButton);
		
		
        add(mainPanel);
		//add listener to the  object
        packageIdentificationTextField.addActionListener(this);
		displayButton.addActionListener(this);
		
	}
	
	public void getInput()
	{
		packageIdentificationString = packageIdentificationTextField.getText();
		poundDouble = Double.parseDouble(poundsTextField.getText()); 
		ouncesDouble = Double.parseDouble(ouncesTextField.getText());
		
	}
	
	public void calculateShipping()
	{
		final double SHIPPING_RATE = .12;
		final double OUNCES_PER_POUND = 16;
		poundToOunceOuncesDouble = poundDouble * OUNCES_PER_POUND;
		shippingCostDouble = (poundToOunceOuncesDouble + ouncesDouble) * SHIPPING_RATE;
		
	}

	public void actionPerformed(ActionEvent evt)
	{
		getInput();
		calculateShipping();
		displayOutput();
		
		
	}
	
	public void displayOutput()
	{
		
	mainPanel.add(new JLabel("Package ID:" + packageIdentificationString));
        mainPanel.add(new JLabel("Weight:" + poundDouble + "lbs" + ouncesDouble + "oz."));
        mainPanel.add(new JLabel("Shipping Cost:" + shippingCostDouble));
	
			
	}
}

here is the code but the output labels aren't showing up. what gives? does it have something to do with positioning?

 

[monjaraz85]

Have you tried NetBeans?? You can graphically make the applet/gui of the program you are writing, it is a lot easier than just writing code. All you have to do is make it and add functionality to the buttons.

 

[piercas]

It is likely that the output labels are not showing up because they have not been added to the mainPanel. In the displayOutput() method, you are creating JLabels but not adding them to the mainPanel. You can add them by using the add() method on the mainPanel, just like you did in the designFrame() method. For example:

mainPanel.add(new JLabel("Package ID:" + packageIdentificationString));

Also, make sure to call the revalidate() and repaint() methods on the mainPanel after adding the labels to ensure they are displayed on the GUI. Additionally, you may need to set the layout of the mainPanel to a layout that allows for multiple components to be added, such as a GridLayout or BorderLayout. I hope this helps solve the issue.