JButton action listener issue. Slider values being displayed in fields

Question 1

What I changed was adding a the listener to both sliders-

slider1.addChangeListener(new SliderListener());
slider2.addChangeListener(new SliderListener());

And also making a change to the slider listener -

private class SliderListener implements ChangeListener {
        public void stateChanged(ChangeEvent e) {
            int max = 0;
            int total = 0;
            // Get the slider value.
            int slider1Val = slider1.getValue();
            int slider2Val = slider2.getValue();
            if (slider1Val > slider2Val) {
                max = slider1Val;
            } else {
                max = slider2Val;
            }
            total = slider2Val + slider1Val;
            // Store the total sound level in its display field.
            totalSound.setText(Integer.toString(total));

            // Store the max sound level in its display field.
            maxSound.setText(Integer.toString(max));
        }
    }

Below is the way the entire edited code -

package org.dchan.orm;

import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JSlider;
import javax.swing.JTextField;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;

/**
 * This class displays a window with a slider component. The user can slide the
 * left or right slider. As the sliders are adjusted it displays the maximum
 * sound level coming from either slider as well as the total.
 */

public class SoundLevels extends JFrame {
    private JLabel label1, label2, label3, label4; // Message labels
    private JTextField maxSound; // Max Sound Level
    private JTextField totalSound; // Total Sound Level
    private JPanel mpanel; // Max sound level panel
    private JPanel tpanel; // Total sound level panel
    private JPanel sliderPanel1; // Slider panel 1
    private JPanel sliderPanel2; // Slider panel 2
    private JPanel resetpanel; // Reset button panel
    private JSlider slider1; // Left sound adjuster
    private JSlider slider2; // Right sound adjuster
    private JButton resetButton; // Reset button

    /**
     * Constructor
     */

    public SoundLevels() {
        // Set the title.
        setTitle("Sound Levels");

        // Specify an action for the close button.
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        // Creates reset button
        resetButton = new JButton("Reset");

        // Create the message labels.
        label1 = new JLabel("Left:  ");
        label2 = new JLabel("Right: ");
        label3 = new JLabel("Max:   ");
        label4 = new JLabel("Total: ");

        // Create the read-only text fields.
        maxSound = new JTextField("0", 10);
        maxSound.setEditable(false);
        totalSound = new JTextField("0", 10);
        totalSound.setEditable(false);

        // Create the slider.
        slider1 = new JSlider(JSlider.HORIZONTAL, 0, 100, 0);
        slider2 = new JSlider(JSlider.HORIZONTAL, 0, 100, 0);
        slider1.addChangeListener(new SliderListener());
        slider2.addChangeListener(new SliderListener());
        // Create panels and place the components in them.
        mpanel = new JPanel();
        resetpanel = new JPanel();
        tpanel = new JPanel();
        sliderPanel1 = new JPanel();
        sliderPanel2 = new JPanel();

        // Add components to panels
        mpanel.add(label1);
        mpanel.add(maxSound);

        tpanel.add(label2);
        tpanel.add(totalSound);

        sliderPanel1.add(label1);
        sliderPanel1.add(slider1);

        sliderPanel2.add(label2);
        sliderPanel2.add(slider2);

        resetpanel.add(resetButton);

        // Initialize event listener
        // resetButton.addActionListener(new ResetButtonListener());

        // Sets window to a border layout format.
        setLayout(new GridLayout(1, 5));

        // Add the panels to the content pane.
        add(sliderPanel1);
        add(sliderPanel2);
        add(resetpanel);
        add(mpanel);
        add(tpanel);

        // Pack and display the frame.
        pack();
        setVisible(true);
    }

    /**
     * Private inner class that handles the event when the user clicks the Reset
     * button.
     */

    /*
     * COMMENTED THIS OUT SO IT AT LEAST RUNS
     */private class ResetButtonListener implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            // Set the panel's background to red.
            // max = 0; // should reset sliders to 0
            // total = 0; // should reset sliders to 0
            slider1.setValue(0);
            slider2.setValue(0);
        }
    }

    /*
*/

    /**
     * Private inner class to handle the change events that are generated when
     * the slider is moved.
     */

    private class SliderListener implements ChangeListener {
        public void stateChanged(ChangeEvent e) {
            int max = 0;
            int total = 0;
            // Get the slider value.
            int slider1Val = slider1.getValue();
            int slider2Val = slider2.getValue();
            if (slider1Val > slider2Val) {
                max = slider1Val;
            } else {
                max = slider2Val;
            }
            total = slider2Val + slider1Val;
            // Store the total sound level in its display field.
            totalSound.setText(Integer.toString(total));

            // Store the max sound level in its display field.
            maxSound.setText(Integer.toString(max));
        }
    }

    /*
     * The main method creates an instance of the class, which displays a window
     * with a slider.
     */

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

Creation of the listener requires a bit of logical understanding. But you need to understand that to get an event you from both sliders the listener should be applied to both. The gist for the entire code is available at - https://gist.github.com/4193279.

For future reference I would suggest you to break your question to few parts.

Question 2

I recommend 2 changes.

slider1.addChangeListener(new SliderListener());
slider2.addChangeListener(new SliderListener()); // newly added

& in the listener:

// Get the slider value.
max = slider1.getValue();
total = slider2.getValue(); // change from 1 -> 2

What is wrong with my action private reset button listener class?

It is about the scope and visibility of the two int attributes. Consider this code, but note that the action performed will not change the slider values, which might be confusing to the user.

// class level attributes that are visible to both
// ResetButtonListener & ResetButtonListener 
private int max, total;             

/**
Private inner class that handles the event when
the user clicks the Reset button.
 */
private class ResetButtonListener implements ActionListener
{
    public void actionPerformed(ActionEvent e)
    {
        // Set the panel's background to red.
        max = 0;  //should reset sliders to 0
        total = 0; //should reset sliders to 0
    }
}

/**
Private inner class to handle the change events
that are generated when the slider is moved.
 */
private class SliderListener implements ChangeListener
{
    public void stateChanged(ChangeEvent e)
    {

        // Get the slider value.
        max = slider1.getValue();
        total = slider2.getValue();

        // Store the total sound level in its display field.
        totalSound.setText(Integer.toString(total));

        // Store the max sound level in its display field.
        maxSound.setText(Integer.toString(max));
    }
}