radio buttons

[melissa84]

Hi all!

I'm making a temperature conversion program, and I'm using radio buttons so the user can select from what temperature to what temperature to convert their number. I've coded an input field key handler so that when a character other than a number is entered, the program will tell the user and backspace the character. But the program doesn't know how to handle a radio button being selected without a character entered.

Here's the code for the radio button handler (I'm not sure if it will be of any help or not):

class RButHandler implements ItemListener
	{
		public void itemStateChanged(ItemEvent e)
		{
			//formats the result temperature to two decimal places
			DecimalFormat num = new DecimalFormat(",###.##");
			//data declaration section
			String instring;
			double temp, outvalue;
			
			if (e.getSource() == rdbutFtoC) //if FtoC button selected
			{	
				instring = enterTempField.getText(); //reads the input into the textfield
				temp = Double.parseDouble(instring); //converts the text to a double
				outvalue = 5.0/9.0 * (temp - 32); //formula for F to C conversion 
				//make answer appear in answer text field
				answerField.setText(temp + " degrees Farenheit is " + num.format(outvalue) + " degrees Celsius.");
			}
			else if (e.getSource() == rdbutCtoF)
			{	
				instring = enterTempField.getText(); //reads the input into the textfield
				temp = Double.parseDouble(instring); //converts the text to a double
				outvalue = (9.0/5.0 * temp) + 32; //formula for C to F conversion
				//make answer appear in answer text field
				answerField.setText(temp + " degrees Celsius is " + num.format(outvalue) + " degrees Farenheit.");
			}
			else if (e.getSource() == rdbutFtoK)
			{	
				instring = enterTempField.getText(); //reads the input into the textfield
				temp = Double.parseDouble(instring); //converts the text to a double
				outvalue = 5.0/9.0 * (temp - 32) + 273; //formula for F to K conversion
				//make answer appear in answer text field
				answerField.setText(temp + " degrees Farenheit is " + num.format(outvalue) + " degrees Kelvin.");
			}
			else if (e.getSource() == rdbutCtoK)
			{	
				instring = enterTempField.getText(); //reads the input into the textfield
				temp = Double.parseDouble(instring); //converts the text to a double
				outvalue = temp + 273; //formula for C to K conversion
				//make answer appear in answer text field
				answerField.setText(temp + " degrees Celsius is " + num.format(outvalue) + " degrees Kelvin.");
			}
			
		}
	}

Thanks!
Melissa

[4fingers]

Hi Melissa,
So if I get you correctly Everything seems to work fine except when there is nothing in the TextField and you click between the radio buttons.

A simple way of solving this would be if there is no data in the TextField make it so none of the calculations are carried out.

One way of doing that is simply add

&& enterTempField.getText().length() != 0

To each of the IF statments. That way it checks to see if the length of the TextField is greater than 0 otherwise it wont carry out any of the calcuations.

So try this for example

class RButHandler implements ItemListener
	{
		public void itemStateChanged(ItemEvent e)
		{
			//formats the result temperature to two decimal places
			DecimalFormat num = new DecimalFormat(",###.##");
			//data declaration section
			String instring;
			double temp, outvalue;
			
			if (e.getSource() == rdbutFtoC && enterTempField.getText().length() != 0) //if FtoC button selected
			{	
				instring = enterTempField.getText(); //reads the input into the textfield
				temp = Double.parseDouble(instring); //converts the text to a double
				outvalue = 5.0/9.0 * (temp - 32); //formula for F to C conversion 
				//make answer appear in answer text field
				answerField.setText(temp + " degrees Farenheit is " + num.format(outvalue) + " degrees Celsius.");
			}
			else if (e.getSource() == rdbutCtoF && enterTempField.getText().length() != 0)
			{	
				instring = enterTempField.getText(); //reads the input into the textfield
				temp = Double.parseDouble(instring); //converts the text to a double
				outvalue = (9.0/5.0 * temp) + 32; //formula for C to F conversion
				//make answer appear in answer text field
				answerField.setText(temp + " degrees Celsius is " + num.format(outvalue) + " degrees Farenheit.");
			}
			else if (e.getSource() == rdbutFtoK && enterTempField.getText().length() != 0)
			{	
				instring = enterTempField.getText(); //reads the input into the textfield
				temp = Double.parseDouble(instring); //converts the text to a double
				outvalue = 5.0/9.0 * (temp - 32) + 273; //formula for F to K conversion
				//make answer appear in answer text field
				answerField.setText(temp + " degrees Farenheit is " + num.format(outvalue) + " degrees Kelvin.");
			}
			else if (e.getSource() == rdbutCtoK && enterTempField.getText().length() != 0)
			{	
				instring = enterTempField.getText(); //reads the input into the textfield
				temp = Double.parseDouble(instring); //converts the text to a double
				outvalue = temp + 273; //formula for C to K conversion
				//make answer appear in answer text field
				answerField.setText(temp + " degrees Celsius is " + num.format(outvalue) + " degrees Kelvin.");
			}
			
		}
	}

There are many other possible ways of doing this like enclosing all of the event handling data in one big IF or instead using something like enterTempField.getText().equalsIgnoreCase("") or enterTempField.getText().matches() and use regular expression to see if the TextField is empty.

Either Way I hope that solves your problem

[melissa84]

Thanks for your help!
Melissa