Equation answer won't output to JTextField with using CoomboBox if statments

I am very new to Java and am taking a Java 1 class. I am trying to use a JComboBox selection in an if statement and then display an answer based on the selection in a JTextField. It all compiled correctly but the answer will not display and I don't Know what i need to change. I've searched and tried several different things but none seemed to work.

import javax.swing.*;
import java.awt.event.*;

public class HayDyGuiTempConv extends JFrame
{

public static void main(String[] args)
{
    new HayDyGuiTempConv();
}

private JButton buttonConvert;
private JButton exitButton;
private JTextField textAmount;
private String fieldText;
private JTextField field;



public HayDyGuiTempConv()
{

    this.setSize(440,150);
    this.setLocation(350,420);
    this.setTitle("Temperature Conversion");
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    ButtonListener bl = new ButtonListener();
    JPanel panel1 = new JPanel();
    panel1.add(new JLabel("Enter temperature to convert: "));

    textAmount = new JTextField(6);
    panel1.add(textAmount);

    JComboBox<String> comboBox = new JComboBox<> (new String[] {"C to F", "F to C"});
    comboBox.addActionListener(bl);
    panel1.add(comboBox);

    buttonConvert = new JButton("Convert");
    buttonConvert.addActionListener(bl);
    buttonConvert.setToolTipText("Convert the temperature.");
    panel1.add(buttonConvert);

    panel1.add(new JLabel("Temp: "));

    field = new JTextField(6);
    field.setEditable(false);
    panel1.add(field);

    exitButton = new JButton("Exit");
    exitButton.addActionListener(bl);
    exitButton.setToolTipText("Exit the program.");
    panel1.add(exitButton);

    this.add(panel1);

    this.setVisible(true);
}

private class ButtonListener implements ActionListener
{

    public void actionPerformed(ActionEvent e)
    {


        if(e.getSource() == buttonConvert)
        {

            if(e.getSource() == ("C to F"))
            {
                double tempEntered = Double.parseDouble(textAmount.getText());
                double tempConverted = tempEntered - 32 * (5/9);
                String tempAmount = (Double.toString(tempConverted));
                field.setText(tempAmount);
            }
            else if(e.getSource() == ("F to C"))
            {
                double tempEntered = Double.parseDouble(textAmount.getText());
                double tempConverted = tempEntered * (9/5) + 32;
                String tempAmount = (String.format("%.2f",(tempConverted)));
                field.setText(tempAmount);
            }
        }
        else if(e.getSource() == exitButton)
        {
            System.exit(0);
        }
    }
}
}