CODEWITHSUNDEEP
javaswingevent-handlingawt
ComicalGamer
ComicalGamer

Reputation: 49

Need help getting this simple Fahrenheit to Celsius application working in java

I need this application to convert the number entered by the user in the JTextField into celsius and display it in a JLabel. It seems to be having problems parsing the the data entered into a double? This is one error among many. Can anyone help me figure out whats wrong? (I've only entered double values in the text field when testing it out and it still wont change it to a double.)

public class TempConvertGUI extends JFrame{
    private JLabel result;
    private final JTextField input;

    public TempConvertGUI()
    {
        super("Fahrenheit to Celsius Application");

        setLayout(new FlowLayout());

        //TempConvert convert=new TempConvert();

        input=new JTextField(10);
        input.setToolTipText("Enter degrees in fahrenheit here.");
        input.addActionListener(new ActionListener()
        {
            private double temp;
            private String string;

            @Override
            public void actionPerformed(ActionEvent event) {
                if(event.getSource()==input)
                {
                    remove(result);
                    if(event.getActionCommand()==null)
                        result.setText(null);
                    else
                    {
                        temp=Double.parseDouble(event.getActionCommand());
                        string=String.format("%d degrees Celsius", convertToCelsius(temp));
                        result.setText(string);;
                    }
                    add(result);
                }
            }

        });
        add(input);

        result=new JLabel();
        add(result);

    }

    private double convertToCelsius(double fahrenheit)
    {
        return (5/9)*(fahrenheit-32);
    }
}

Upvotes: 3

Views: 89

Answers (3)

MChaker
MChaker

Reputation: 2649

It seems you got this exception

java.util.IllegalFormatConversionException: d != java.lang.Double

And it is because of this line of code

string=String.format("%d degrees Celsius", convertToCelsius(temp));

%d represents an integer; you want to use %f for a double (convertToCelsius returns a double).

So change it to

string=String.format("%f degrees Celsius", convertToCelsius(temp));

Upvotes: 2

copeg
copeg

Reputation: 8348

  1. The ActionCommand for the the JTextField was never set, so it will be an empty String. If you want to parse the data within the JTextField, then get its value and parse that value (eg temp=Double.parseDouble(input.getText());)
  2. See the API for formatting strings - use an %f to parse floating point values
  3. No need to add and remove the result JLabel in ActionPerformed, it has already been added to the UI - just set it's text
  4. (5/9) is integer math, if you want floating point math then specify one of the numbers as the proper data type: (5/9d)

Upvotes: 3

M. Shaw
M. Shaw

Reputation: 1742

Instead of temp=Double.parseDouble(event.getActionCommand());, you should be parsing the input from input.getText().

Upvotes: 0

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