NumberFormatException in a multi-frame GUI

Question

I'm in a rather unique situation based on what I've seen in other's coding. I'm working on a multi-frame GUI for a school project and it has four converters between various units: Mass, Volume, Distance, and Temperature. The problem I run into lies with the Text Listeners for my temperature conversions:

private class TempListener implements ActionListener{ 
    public void actionPerformed (ActionEvent event){ 
        double faren, cels; 
        String text = temperature.getText(); 
        faren = Integer.parseInt(text); 
        cels = (faren-32) * 5/9; 
        rLabelT.setText(Double.toString(cels)); 
    } 
} 

private class Temp1Listener implements ActionListener{ 
    public void actionPerformed (ActionEvent event){ 
        double faren, cels; 
        String text = temperature1.getText(); 
        cels = Integer.parseInt(text); 
        faren = (cels+32) * 9/5; 
        rLabelT1.setText(Double.toString(faren)); 
    } 
} 

The Integer.parseInt method catches a NumberFormatException.java and stops it from completing the calculation. Now, this coding is almost identical to a similar program from my textbook with the only edits being the variable type. What I worry about is that the other frames have fully functional calculations based on the same block:

private class MassListener implements ActionListener{ 
    public void actionPerformed (ActionEvent event){ 
        double pounds, kilograms; 
        String text = mass.getText(); 
        pounds = Integer.parseInt(text); 
        kilograms = pounds/2.2; 
        rLabelM.setText(Double.toString(kilograms)); 
    } 
} 
private class VolumeListener implements ActionListener{ 
    public void actionPerformed (ActionEvent event){ 
        double litres, gallons; 
        String text = volume.getText(); 
        gallons = Integer.parseInt(text); 
        litres = .264 * gallons; 
        rLabelV.setText(Double.toString(litres)); 
    } 
} 
private class DistListener implements ActionListener{ 
    public void actionPerformed (ActionEvent event){ 
        double miles, kilo; 
        String text = distance.getText(); 
        miles = Integer.parseInt(text); 
        kilo = miles * 1.609; 
        rLabelD.setText(Double.toString(kilo)); 
    } 
} 

All of these work with EXACTLY the same coding without any errors. How do I fix this? It's the last issue in my code to address.

The code to open the frame that contains the temp conversions:

   private class ButtonTListener implements ActionListener{ 
    public void actionPerformed (ActionEvent event){ 
        JFrame dialogT = new JFrame ("Temperature"); 
        dialogT.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE); 
        dialogT.setBounds(750,650,400,150); 
        dialogT.setVisible(true); 
        iLabelT = new JLabel ("Enter a Temperature in Farenheit: "); 
        oLabelT = new JLabel ("Temperature in Celsius: "); 
        rLabelT = new JLabel ("--"); 
        temperature = new JTextField (5); 
        temperature.addActionListener(new TempListener()); 
        iLabelT1 = new JLabel ("Enter a Temperature in Celsius: "); 
        oLabelT1 = new JLabel ("Temperature in Farenheit: "); 
        rLabelT1 = new JLabel ("--"); 
        temperature1 = new JTextField (5); 
        temperature.addActionListener(new Temp1Listener()); 
        Temperature1 = new JPanel(); 
        Temperature1.setPreferredSize(new Dimension (400,100)); 
        Temperature1.setLayout(new FlowLayout()); 
        Temperature1.setBackground (Color.yellow); 
        Temperature1.add(iLabelT); 
        Temperature1.add(temperature); 
        Temperature1.add(oLabelT); 
        Temperature1.add(rLabelT); 
        Temperature1.add(iLabelT1); 
        Temperature1.add(temperature1); 
        Temperature1.add(oLabelT1); 
        Temperature1.add(rLabelT1); 
        dialogT.getContentPane().add(Temperature1); 
    } 
} 

Answer 1

You declare double values, and then try to parse them with Integer. An integer is, by any definition, a number with no decimal place. So when Java encounters any decimal place in your input, it will fail. Instead, you should be trying to parse them using Double.

For example:

    double d1, d2;
    try
    {
        System.out.println("Parsing d1...");
        d1 = Integer.parseInt("5.4");    // using Integer to parse a double fails
        System.out.println("d1: " + d1);
    }
    catch (NumberFormatException e1)
    {
        System.err.println("exception parsing 5.4 as an integer");
        e1.printStackTrace();
    }

    try
    {
        System.out.println("Parsing d2...");
        d2 = Double.parseDouble("5.4");    // using Double to parse a double succeeds
        System.out.println("d2: " + d2);
    }
    catch (NumberFormatException e2)
    {
        System.err.println("exception parsing 5.4 as a double");
        e2.printStackTrace();
    };

Output:

Parsing d1...
exception parsing 5.4 as an integer
java.lang.NumberFormatException: For input string: "5.4"
    at java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)
    at java.lang.Integer.parseInt(Integer.java:458)
    at java.lang.Integer.parseInt(Integer.java:499)
    at pkg.Main.main(Main.java:40)
Parsing d2...
d2: 5.4