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I’m working on a Java Swing application that includes a music equalizer. The application is supposed to allow users to select an MP3 file and visualize the audio levels in real-time. However, when I select an MP3 file, the application does nothing, and no audio is played

I also added a sample.txt (private static final String DEFAULT_MP3_PATH = “sample.mp3”) but the issue resists

import javax.swing.*;
import javax.swing.filechooser.FileNameExtensionFilter;
import java.awt.*;
import java.io.*;
import javazoom.jl.player.*;
// import javazoom.jl.decoder.*;

public class MusicEqualizer extends JFrame {
    private static final int BANDS = 32;
    private static final int MAX_HEIGHT = 100;
    private static final int FFT_SIZE = 1024;
    private int[] levels = new int[BANDS];
    private Color[] colors = new Color[BANDS];
    private Player player;
    private byte[] buffer;
    private double[] fftData;
    private boolean isPlaying = false;

    public MusicEqualizer() {
        setTitle("Music Equalizer");
        setSize(800, 200);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        initializeColors();
        buffer = new byte[FFT_SIZE * 2];
        fftData = new double[FFT_SIZE * 2];

        JPanel equalizerPanel = new JPanel() {
            @Override
            protected void paintComponent(Graphics g) {
                super.paintComponent(g);
                drawEqualizer(g);
            }
        };
        add(equalizerPanel);

        JButton selectFileButton = new JButton("Select File");
        selectFileButton.addActionListener(e -> selectFile());
        add(selectFileButton, BorderLayout.SOUTH);
    }

    private void initializeColors() {
        for (int i = 0; i < BANDS; i++) {
            float hue = (float) i / BANDS;
            colors[i] = Color.getHSBColor(hue, 1.0f, 1.0f);
        }
    }

    private void drawEqualizer(Graphics g) {
        int width = getWidth();
        int bandWidth = width / BANDS;

        for (int i = 0; i < BANDS; i++) {
            int x = i * bandWidth;
            int y = getHeight() - levels[i];
            int height = levels[i];

            g.setColor(colors[i]);
            g.fillRect(x, y, bandWidth - 1, height);
        }
    }

    private void updateLevels(InputStream is) {
        try {
            int bytesRead = is.read(buffer, 0, buffer.length);
    
            if (bytesRead > 0) {
                for (int i = 0; i < FFT_SIZE * 2; i++) {
                    fftData[i] = (i < bytesRead) ? buffer[i] / 128.0 : 0.0;
                }
    
                fft(fftData);
    
                for (int i = 0; i < BANDS; i++) {
                    double sum = 0;
                    for (int j = i * 16; j < (i + 1) * 16 && j < FFT_SIZE; j++) {
                        sum += Math.sqrt(fftData[2 * j] * fftData[2 * j] + fftData[2 * j + 1] * fftData[2 * j + 1]);
                    }
                    levels[i] = (int) Math.min(MAX_HEIGHT, sum / 16 * MAX_HEIGHT);
                }
    
                repaint();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }    


    private void fft(double[] x) {
        int n = x.length / 2;

        // bit reversal
        int j = 0;
        for (int i = 0; i < n - 1; i++) {
            if (i < j) {
                double temp = x[2*i];
                x[2*i] = x[2*j];
                x[2*j] = temp;
                temp = x[2*i+1];
                x[2*i+1] = x[2*j+1];
                x[2*j+1] = temp;
            }
            int k = n / 2;
            while (k <= j) {
                j -= k;
                k /= 2;
            }
            j += k;
        }

        // FFT
        for (int l = 2; l <= n; l *= 2) {
            double angle = -2 * Math.PI / l;
            double wr = Math.cos(angle);
            double wi = Math.sin(angle);
            for (int i = 0; i < n; i += l) {
                double tr = 1.0, ti = 0.0;
                for (int m = 0; m < l / 2; m++) {
                    int p = i + m;
                    int q = i + m + l / 2;
                    double sr = x[2*q] * tr - x[2*q+1] * ti;
                    double si = x[2*q] * ti + x[2*q+1] * tr;
                    x[2*q] = x[2*p] - sr;
                    x[2*q+1] = x[2*p+1] - si;
                    x[2*p] += sr;
                    x[2*p+1] += si;
                    double tr_temp = tr;
                    tr = tr * wr - ti * wi;
                    ti = tr_temp * wi + ti * wr;
                }
            }
        }
    }

    private void selectFile() {
        JFileChooser fileChooser = new JFileChooser();
        FileNameExtensionFilter filter = new FileNameExtensionFilter("MP3 Files", "mp3");
        fileChooser.setFileFilter(filter);
        
        int result = fileChooser.showOpenDialog(this);
        
        if (result == JFileChooser.APPROVE_OPTION) {
            File selectedFile = fileChooser.getSelectedFile();
            playFile(selectedFile);
        }
    }

    private void playFile(File file) {
        stopPlayback();
        try {
            FileInputStream fis = new FileInputStream(file);
            BufferedInputStream bis = new BufferedInputStream(fis);
            player = new Player(bis);
    
            new Thread(() -> {
                try {
                    isPlaying = true;
                    player.play();
                } catch (Exception e) {
                    e.printStackTrace();
                } finally {
                    isPlaying = false;
                    try {
                        bis.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }).start();
    
            new Thread(() -> {
                try {
                    while (isPlaying && !player.isComplete()) {
                        updateLevels(bis);
                        Thread.sleep(20);
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }).start();
    
        } catch (Exception e) {
            e.printStackTrace();
        }
    }    

    private void stopPlayback() {
        isPlaying = false;
        if (player != null) {
            player.close();
            player = null;
        }
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> {
            MusicEqualizer equalizer = new MusicEqualizer();
            equalizer.setVisible(true);
        });
    }
}