Input Validation and my struggles with it

[Snipe Anthony]

Okay so I posted on here previously and people helped me out tremendously. I only have only one issue with my code now that I can't seem to figure out. That is how to add an input validation "invalid input, number has to be positive" dialog, after a user input of 0 or a negative number for length (tLength) and width (tWidth) to find the area.

Here is my code which runs fine, just needs the validation added:

import java.awt.event.*;
import javax.swing.*;
import java.awt.*;
        
public class FloorsRUs extends JFrame implements ActionListener, ItemListener {

public JTabbedPane jTP;
public JRadioButton flrWood = null;
public JRadioButton flrCarpet = null;
public JTextField tCName;
public JTextField tAddress;
public JTextField tLength;
public JTextField tWidth;
public JButton calcArea;
public JButton calcCost;
public JButton subOrder;
public JButton orderSum;
public JButton ordList;
public JPanel flrPan;
public JPanel lwPan;
public JPanel cPan;
public JLabel lab1;
public JLabel lab2;
public JLabel lab3;
public JLabel lab4;
public String flrType;
public double area = 0;
public double cost = 0;


FloorsRUs(String title)
	        
{
super(title);
jTP=new JTabbedPane();
flrPan=new JPanel();
lwPan=new JPanel();
cPan=new JPanel();

flrPan.add(flrWood=new JRadioButton("Choose Wood"));
flrPan.add(flrCarpet=new JRadioButton("Choose Carpet"));
        
ButtonGroup grp = new ButtonGroup();
grp.add(flrWood);
grp.add(flrCarpet);
	      
lwPan.add(lab1=new JLabel("Enter the Length : "));
lwPan.add(tLength=new JTextField(10));

lwPan.add(lab2=new JLabel("Enter the Width"));
lwPan.add(tWidth=new JTextField(10));

lwPan.add(calcArea=new JButton("Calculate the Area"));
lwPan.add(calcCost=new JButton("Calculate the Cost"));
lwPan.add(subOrder=new JButton("Submit the Order"));

cPan.add(lab3=new JLabel("Enter the Customers Name : "));
cPan.add(tCName=new JTextField(10));

cPan.add(lab4=new JLabel("Enter the Customers Address : "));
cPan.add(tAddress=new JTextField(10));

cPan.add(orderSum=new JButton("The Order Summary"));
cPan.add(ordList=new JButton("The Order List"));

jTP.addTab("Select Floor Type ",flrPan);
jTP.addTab("Enter Length and Width ",lwPan);
jTP.addTab("Customer Info",cPan);
add(jTP);

calcArea.addActionListener(this);
calcCost.addActionListener(this);
subOrder.addActionListener(this);
orderSum.addActionListener(this);
ordList.addActionListener(this);
flrWood.addItemListener(this);
flrCarpet.addItemListener(this);


}
@Override
public void itemStateChanged(ItemEvent ie)

{
if(flrWood.isSelected()){
flrType="Wood";

}

else if(flrCarpet.isSelected()){
flrType="Carpet";
}

}
	      
@Override
public void actionPerformed(ActionEvent ae)
{

String source=ae.getActionCommand();

switch (source) {
    
case "Calculate the Area":
System.out.println("Calc 1 Complete");
area=Double.parseDouble(tLength.getText())
*Double.parseDouble(tWidth.getText());
break;

case "Calculate the Cost":
System.out.println("Calc 2 Complete");
if(flrType.equals("Wood"))
cost = area *20;
else if(flrType.equals("Carpet"))
cost = area *10;
break;
                    
case "The Order Summary":
JOptionPane.showMessageDialog(null,"The Order Summary - Area is :" + ""+area+""
+ " The Cost is :  "+cost," Information",
JOptionPane.INFORMATION_MESSAGE);
break;
                    
case "The Order List":
JOptionPane.showMessageDialog(null,"The Order List : \n Customer's name : "+tCName.getText()
+"\nAddress : "+tAddress.getText()
+"\n The Area is :"+area
+"\n The Cost is : "+cost,"Information",
JOptionPane.INFORMATION_MESSAGE);
break;
                    
default:

break;
}



}  
	      
public static void main(String args[])

{
FloorsRUs f1=new FloorsRUs("FloorsRUs Easy App");
f1.setSize(new Dimension(650,450));
f1.setVisible(true);
}

}

I've tried:

if(tLength.getText()<=0 && tWidth.getText()<=0)
{
    System.out.println("invalid input, number has to be positive");
}

And it received errors for  "Bad operand for binary operator '<='". I believe because tLength and tWidth are both String.

So then I tried:

case "Calculate the Area":
System.out.println("Calc 1 Complete");
area=Double.parseDouble(tLength.getText())
*Double.parseDouble(tWidth.getText());
if((Double.parseDouble(tLength.getText())<=0) && ((Double.parseDouble(tWidth.getText())<=0)))
{
       System.out.println("invalid input, number has to be positive");
}
break;

It accepted it but didn't change the output when I put a 0 or negative number into the Length or Width field.

So finally I tried:

case "Calculate the Area":
			System.out.println("Calc 1 Complete");
			try {
				if ((Double.parseDouble(tLength.getText()) < 0)
						&& ((Double.parseDouble(tWidth.getText()) < 0))) {
					System.out.println("invalid input, number has to be positive");
				} else {
					area = Double.parseDouble(tLength.getText()) * Double.parseDouble(tWidth.getText());
				}
 
			} catch (NumberFormatException e) {
				System.out.println("invalid input, number has to be positive");
			}
			break;

Also, no errors but it didn't work when negative numbers or 0 were entered.

**If someone can enter me in the right direction it would be much appreciated, I feel I have been stuck for days.**

[Carey Brown]

Your problem is "&&".

[Snipe Anthony]

Does it need to be ||?

[Carey Brown]

Say it out loud...

if( length < 0 && width < 0 )

or

if( length < 0 || width < 0 )

[Snipe Anthony]

Yeah that makes sense even more when I do say it out loud but the problem is it still doesn't output.

[Carey Brown]

I don't see a problem with your last code snippet other than &&. You might want to throw in some prints for getText() to see if you get what you expect. I would also suggest initializing area to zero before entering the try block.

[Carey Brown]

Snipe Anthony wrote:the problem is it still doesn't output.

Your problem may be that you're mixing a GUI interface with a text interface. Have you tried using a JOptionPane to display the error message?

[Snipe Anthony]

I have not, I will try.

[Carey Brown]

System.out.println("Calc 1 Complete");

Do you see this output appear anywhere?

[Snipe Anthony]

Yes it shows up in the system output.

[Carey Brown]

Then JOptionPane is not the solution (though you might want it at a later date).

[Snipe Anthony]

Just a question, why would it matter if I could see that message in the system output or not? (Future Reference)

[John Joe]

It accepted it but didn't change the output when I put a 0 or negative number into the Length or Width field.

Beside the || operator, you also need to change the operator from < to <= to detect value 0

[Snipe Anthony]

I changed that as well and it still won't output. Is this the john joe from javaprogrammingforums? If so it's Snipe from yesterday hah.

[John Joe]

Snipe Anthony wrote:I changed that as well and it still won't output. Is this the john joe from javaprogrammingforums? If so it's Snipe from yesterday hah.

Yes, is me
What output is not showing up ?

[Snipe Anthony]

The "invalid input, number has to be positive" output. It still won't register and execute.

[John Joe]

Snipe Anthony wrote:The "invalid input, number has to be positive" output. It still won't register and execute.

In this line

System.out.println("invalid input, number has to be positive");

The output will shows in system only. If you want to display it as dialog, use JOptionPane instead

[Snipe Anthony]

John Joe wrote:

Snipe Anthony wrote:The "invalid input, number has to be positive" output. It still won't register and execute.

In this line

System.out.println("invalid input, number has to be positive");

The output will shows in system only. If you want to display it as dialog, use JOptionPane instead

So would it be like:

case "Calculate the Area":
			System.out.println("Calc 1 Complete");
			try {
				if ((Double.parseDouble(tLength.getText()) < 0)
						&& ((Double.parseDouble(tWidth.getText()) < 0))) {
					JOptionPane.showMessageDialog(null, "invalid input, number has to be positive",JOptionPane.ERROR_MESSAGE);
				} else {
					area = Double.parseDouble(tLength.getText()) * Double.parseDouble(tWidth.getText());
				}
 
			} catch (NumberFormatException e) {
				    JOptionPane.showMessageDialog(null, "invalid input, number has to be positive",JOptionPane.ERROR_MESSAGE);
;
			}
			break;

[Snipe Anthony]

I meant:

case "Calculate the Area":
			System.out.println("Calc 1 Complete");
			try {
				if ((Double.parseDouble(tLength.getText()) <=0)
						|| ((Double.parseDouble(tWidth.getText()) <=0))) {
					JOptionPane.showMessageDialog(null, "invalid input, number has to be positive",JOptionPane.ERROR_MESSAGE);
				} else {
					area = Double.parseDouble(tLength.getText()) * Double.parseDouble(tWidth.getText());
				}
 
			} catch (NumberFormatException e) {
				    JOptionPane.showMessageDialog(null, "invalid input, number has to be positive",JOptionPane.ERROR_MESSAGE);
;
			}
			break;

[John Joe]

Yes,but you miss one arguments for showMessageDialog method.It requires four arguments

public static void showMessageDialog(Component parentComponent,
        Object message, String title, int messageType)
        throws HeadlessException {
        showMessageDialog(parentComponent, message, title, messageType, null);
    }

[Snipe Anthony]

Okay so I am a little confused, where would I put that?

[John Joe]

Snipe Anthony wrote:Okay so I am a little confused, where would I put that?

Just add a string as dialog title

JOptionPane.showMessageDialog(null, "invalid input, number has to be positive", "Error", JOptionPane.INFORMATION_MESSAGE);

[Snipe Anthony]

I updated the code to:

case "Calculate the Area": 
System.out.println("Calc 1 Complete"); 
try { 
if ((Double.parseDouble(tLength.getText()) <=0) 
|| ((Double.parseDouble(tWidth.getText()) <=0))) { 
JOptionPane.showMessageDialog(null, "invalid input, number has to be positive", "Error", JOptionPane.ERROR_MESSAGE); 
} else { 
area = Double.parseDouble(tLength.getText()) * Double.parseDouble(tWidth.getText()); 
} 
} catch (NumberFormatException e) { 
    JOptionPane.showMessageDialog(null, "invalid input, number has to be positive", "Error", JOptionPane.ERROR_MESSAGE);  
} 
break;

No errors but it still won't output

[Snipe Anthony]

Whoa. sorry computer is spazzing out. Didn't mean to post that 3 times, sorry!

[John Joe]

Snipe Anthony wrote:Whoa. sorry computer is spazzing out. Didn't mean to post that 3 times, sorry!

Output not showing up on both ?

[Snipe Anthony]

Neither one of the outputs come up in a dialog box when I enter a negative number or 0. So frustrating, I am about to call it quits.

[John Joe]

It works in my PC

[Snipe Anthony]

Will you post the entire source code so I can see if I have everything done correctly?

[Campbell Ritchie]

John Joe wrote:. . . you also need to change the operator from < to <= to detect value 0

But the OP was already using <=

[Campbell Ritchie]

Only use null as the first argument for a show dialogue method if you don't have a GUI; null will make the dialogue appear in the centre of the screen. Use the name of a GUI component you want the dialogue to appear in the same location as (middle of the component named). Does the display become unresponsive and no dialogue appear? In that case minimise everything on your screen; I have known such dialogues to appear behind something and be invisible.

[John Joe]

Campbell Ritchie wrote:But the OP was already using <=

The OP had remove that <= operator when he used try and catch in the latest code