Java 通过在JComboBox中选择将枚举值传递给函数

我只是有一个很好的想法，但后来我意识到我在Java中太笨了，无法做到这一点。我的想法是这样的：

import java.awt.*;
import java.awt.event.*;
import javax.sound.sampled.LineUnavailableException;
import javax.swing.*;
import javax.swing.border.BevelBorder;
import javax.swing.event.*;

import java.awt.*;

public class Window extends JPanel implements ActionListener
{
private JMenuBar mainMenu = new JMenuBar();

private Plot plot = new Plot();
private Parameters param = new Parameters();

private JButton playSound = new JButton("Play");
private JButton getSample = new JButton("Save wave");
private JButton getPlot = new JButton("Save plot");

private Chords music = new Chords();

private JPanel mainPanel = new JPanel();
private JPanel subPanel = new JPanel();
private JPanel buttonsPanel = new JPanel();
private JPanel slidersPanel = new JPanel();

private JLabel chord = new JLabel("Chord:");

private JTextField aValue = new JTextField();
private JTextField fValue = new JTextField(); 
private JTextField pValue = new JTextField();

public Window() 
{
    mainPanel.setLayout(new FlowLayout());
    buttonsPanel.setLayout(new BoxLayout(buttonsPanel, BoxLayout.Y_AXIS));
    slidersPanel.setLayout(new BorderLayout());
    subPanel.setLayout(new BorderLayout());

    buttonsPanel.add(chord);
    buttonsPanel.add(music);
    buttonsPanel.add(Box.createRigidArea(new Dimension(0,10)));
    buttonsPanel.add(playSound);
    buttonsPanel.add(Box.createRigidArea(new Dimension(0,10)));
    buttonsPanel.add(getSample);
    buttonsPanel.add(Box.createRigidArea(new Dimension(0,10)));
    buttonsPanel.add(getPlot);
    buttonsPanel.setBorder(BorderFactory.createTitledBorder("Menu"));

    JMenu langMenu = new JMenu("Language");

    param.addAmplitudeListener(new ChangeListener()
    {
        public void stateChanged(ChangeEvent a)
        {
            int ampValue = param.getAmplitudeValue();
            aValue.setText(String.valueOf(ampValue));
        }
    }
    );


    param.addFrequencyListener(new ChangeListener()
    {
        public void stateChanged(ChangeEvent f)
        {
            double frValue = param.getFrequencyValue();
            fValue.setText(String.valueOf(frValue));
        }
    }
    );


    param.addPhaseListener(new ChangeListener()
    {
        public void stateChanged(ChangeEvent p)
        {
            double phValue = param.getPhaseValue();
            pValue.setText(String.valueOf(phValue));
        }
    }
    );

    playSound.addActionListener(this);
    getPlot.addActionListener(this);
    getSample.addActionListener(this);

    mainMenu.add(langMenu);
    slidersPanel.add(param);
    subPanel.add(buttonsPanel, BorderLayout.NORTH);
    subPanel.add(slidersPanel, BorderLayout.SOUTH);
    mainPanel.add(subPanel);
    mainPanel.add(plot);
    add(mainPanel);


}

public void actionPerformed(ActionEvent a)
{
    Object button = a.getSource();

    if(button==playSound)
        try 
        {
            Audio.playChord(frequencies);
        } 

        catch (LineUnavailableException e) 
        {
            System.out.println("Error");
        }
}

public JMenuBar getmainMenu()
{
    return mainMenu;
}

private static void GUI()
{
    Window mainPanel = new Window();
    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.getContentPane().add(mainPanel);
    frame.setJMenuBar(mainPanel.getmainMenu());
    frame.pack();
    frame.setVisible(true);
    Menu theme = new Menu();
    theme.setVisible(true);
    theme.pack();
}

public static void main(String[] args) 
{
    SwingUtilities.invokeLater(new Runnable() 
    {
         public void run()
         {
            GUI();
         }
      }
      );
}
}

我们有一个名为test（到现在为止）的类，它有一个枚举音调-正如您可以看到的，每个音调都有频率值。当然，我们有getChord（）函数来获取这些值

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

public class test 
{
public enum Tones
{
    C(261.6), CSHARP(277.2), D(293.7), DSHARP(311.2), E(329.6), F(349.6), FSHARP(370), G(391.9), GSHARP(415.3), A(440), B(466.2), H(493.9);

    private double frequencyVal;

    Tones(double frequencyVal)
    {
        this.frequencyVal = frequencyVal;
    }

    public double getChord()
    {
        return frequencyVal;
    }
    };
}

然后我们有一个名为chord的类，JComboBox在其中。我们可以简单地从中选择一个和弦

import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;

import javax.swing.*;


class Chords extends JPanel
{
private JComboBox chooseChord = new JComboBox(new String[]{"C", "C#", "D", "D#", "E", "F", "F#", "G", "G#", "A", "B", "H"});

public Chords() 
{
    chooseChord.setSelectedItem(null);

    chooseChord.addItemListener(new ItemListener() 
    {
        @Override
        public void itemStateChanged(ItemEvent e) 
        {
            Object item = chooseChord.getSelectedItem();

            if ("A".equals(item)) 
            {

            } 

            else if ("B".equals(item)) 
            {

            }

            else if ("H".equals(item)) 
            {

            }

            else if ("C".equals(item)) 
            {

            }

            else if ("C#".equals(item)) 
            {

            }

            else if ("D".equals(item)) 
            {

            }

            else if ("D#".equals(item)) 
            {

            }

            else if ("E".equals(item)) 
            {

            }

            else if ("F".equals(item)) 
            {

            }

            else if ("F#".equals(item)) 
            {

            }

            else if ("G".equals(item)) 
            {

            }

            else if ("G#".equals(item)) 
            {

            }
        }
    });

    add(chooseChord);
}   
}

这就是最难的部分。我希望我能尽可能简单地描述它

通过在JComboBox中选择和弦，我想从enum中选择一组三种特定的音调。然后我想把这三个特定的值传递给playChord（）函数，它也在另一个类中（代码末尾）。我只是在那里输入了随机频率值

import java.applet.*;
import java.io.*;
import java.net.*;

import javax.sound.sampled.*;

public final class Audio 
{

    public static final int SAMPLE_RATE = 44100;

    private static final int BYTES_PER_SAMPLE = 2;                // 16-bit audio
    private static final int BITS_PER_SAMPLE = 16;                // 16-bit audio
    private static final double MAX_16_BIT = Short.MAX_VALUE;     // 32,767
    private static final int SAMPLE_BUFFER_SIZE = 4096;

    private static SourceDataLine line;   // to play the sound
    private static byte[] buffer;         // our internal buffer
    private static int bufferSize = 0;    

    private static double amplitude, frequency, phase;

    // not-instantiable
    private Audio() { }

    // static initializer
    static { init(); }

    // open up an audio stream
private static void init() 
{

try 
{
    // 44,100 samples per second, 16-bit audio, mono, signed PCM, little Endian
    AudioFormat format = new AudioFormat((float) SAMPLE_RATE, BITS_PER_SAMPLE, 1, true, false);
    DataLine.Info info = new DataLine.Info(SourceDataLine.class, format);

    line = (SourceDataLine) AudioSystem.getLine(info);
    line.open(format, SAMPLE_BUFFER_SIZE * BYTES_PER_SAMPLE);

    buffer = new byte[SAMPLE_BUFFER_SIZE * BYTES_PER_SAMPLE/3];
}

catch (Exception e) 
{
    System.out.println(e.getMessage());
    System.exit(1);
}

// no sound gets made before this call
line.start();
}

public void setAmplitude(double a)
{
    amplitude = a;
}

public static void setFrequency(double f)
{
    frequency = f;
}

public void SetPhase(double p)
{
    phase = p;
}

public static double getAmplitude()
{
    return amplitude;
}

public static double getFrequency()
{
    return frequency;
}

public static double getPhase()
{
    return phase;
}

/**
 * Close standard audio.
 */
public static void close() 
{
line.drain();
line.stop();
}

/**
 * Write one sample (between -1.0 and +1.0) to standard audio. If the sample
 * is outside the range, it will be clipped.
 */
public static void play(double in) 
{

// clip if outside [-1, +1]
if (in < -1.0) in = -1.0;
if (in > +1.0) in = +1.0;

// convert to bytes
short s = (short) (MAX_16_BIT * in);
buffer[bufferSize++] = (byte) s;
buffer[bufferSize++] = (byte) (s >> 8);   // little Endian

// send to sound card if buffer is full        
if (bufferSize >= buffer.length) 
{
    line.write(buffer, 0, buffer.length);
    bufferSize = 0;
}
}

/**
 * Write an array of samples (between -1.0 and +1.0) to standard audio. If a     sample
 * is outside the range, it will be clipped.
 */
public static void play(double[] input) 
{
for (int i = 0; i < input.length; i++) 
{
    play(input[i]);
}
}

private static double[] tone(double hz, double duration, double amplitude, double phase) 
{
int N = (int) (Audio.SAMPLE_RATE * duration);
double[] a = new double[N+1];
for (int i = 0; i <= N; i++)
    a[i] = amplitude * Math.sin(2 * Math.PI * i * hz / Audio.SAMPLE_RATE + phase);
return a;
}

public static void playChord() throws LineUnavailableException 
{
double[] a = tone(415.3, 1.0, 1, 0);
double[] b = tone(329.6, 1.0, 1, 0);
double[] c = tone(493.9, 1.0, 1, 0);

for( int i=0; i<a.length; ++ i )
   a[i] = (a[i] + b[i] + c[i]) / 3;

Audio.play(a);
}

public static void playSound() throws LineUnavailableException
{
double[] a = tone(getFrequency(), 1.0, getAmplitude(), getPhase());

for( int i = 0; i < a.length; ++ i )
       a[i] = (a[i]);

Audio.play(a);
}
}

---

这就是我定义按钮actionlisteners的地方。由于我的声誉太低，目前无法发布图片，所以我无法向您展示完整的GUI。发布所有类太难了。

如果愿意，可以将枚举设置为主类，并让它返回用于组合框的字符串列表、音调和所有内容。将其视为“数据库”类。然后让其他人从中请求数据并对值进行操作

---

对于“全局”函数（不特定于枚举的一个实例，例如“Tones.C.function（）”而是“Tones.function（）”），请使用静态函数。

您需要做的一件事是修改

playChord

方法，以便它接受您的频率数组（您以某种方式从用户处检索到的）。您可以使用如下内容。除了使用数组而不是硬编码的

a

、

b

和

c

之外，这与您已经在做的事情几乎相同

public static void playChord(double[] frequencies)
    throws LineUnavailableException 
{
    double[] buffer = tone(frequencies[0], 1.0, 1, 0);

    for(int i = 1; i < frequencies.length; ++i) {
        double[] harmonic = tone(frequencies[i], 1.0, 1, 0);

        for(int i = 0; i < buffer.length; ++i) {
            buffer[i] += harmonic[i];
        }
    }

    for(int i = 0; i < buffer.length; ++i) {
        buffer[i] /= frequencies.length;
    }

    Audio.play(buffer);
}

如果你的想法是用户单独选择和弦中的音符，你也可以考虑使用A。只是一个建议<代码>JList允许用户选择多个项目

import java.util.*;
import javax.swing.*;
import java.awt.BorderLayout;

class ToneList implements Runnable {
    public static void main(String[] args) {
        SwingUtilities.invokeLater(new ToneList());
    }

    enum Tone {…} // same as above

    @Override
    public void run() {
        final JFrame   frame = new JFrame();
        final JPanel content = new JPanel(new BorderLayout());
        final JList     list = new JList(Tone.values());
        final JButton button = new JButton("Play");

        button.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent ae) {
                Object[] values = list.getSelectedValues();
                double[] chord  = new double[values.length];

                for(int i = 0; i < chord.length; ++i) {
                    Tone tone = (Tone)values[i];
                    chord[i]  = tone.hz;
                }

                JOptionPane.showMessageDialog(null,
                    "Chord selected: " + Arrays.toString(chord)
                );
            }
        });

        content.add(list, BorderLayout.CENTER);
        content.add(button, BorderLayout.SOUTH);

        frame.setContentPane(content);
        frame.pack();
        frame.setResizable(false);
        frame.setLocationRelativeTo(null);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
    }
}

import java.util.*；
导入javax.swing.*；
导入java.awt.BorderLayout；
类ToneList实现Runnable{
公共静态void main（字符串[]args）{
调用器（新的音调列表（））；
}
枚举音调{…}//同上
@凌驾
公开募捐{
最终JFrame=新JFrame（）；
最终JPanel内容=新JPanel（新BorderLayout（））；
最终JList列表=新JList（Tone.values（））；
最终按钮=新按钮（“播放”）；
addActionListener（新建ActionListener（））{
@凌驾
已执行的公共无效行动（行动事件ae）{
Object[]values=list.getSelectedValues（）；
double[]chord=新的double[values.length]；
对于（int i=0；i

---

我希望这能给你一些想法来弥补你所缺少的。

嗨，非常感谢你的回复。你的第一个例子看起来就像我需要的一样，我马上就要尝试一下。我刚刚发布了我的主要功能。问题是我在那里定义了所有按钮ActionListener。老实说，我们应该在没有Java知识的情况下，在大学里作为一个项目编写这样一个程序。当然，我们有讲座和实验室，但它们太混乱了，我什么都学不到。具体问题是什么？因为在chord类中有一个私有的JComboBox，如果您想在其他地方添加一个动作侦听器，就需要公开它。假设您有一些代码，比如

aButton.addActionListener（new ActionListener（）{public void actionPerformed（…）{JComboBox=music.getComboBox（）；…}}）

。希望有帮助。如果你需要更多的超出这个问题的原始范围，你可以考虑问一个新问题。

import java.util.*;
import javax.swing.*;
import java.awt.BorderLayout;

class ToneList implements Runnable {
    public static void main(String[] args) {
        SwingUtilities.invokeLater(new ToneList());
    }

    enum Tone {…} // same as above

    @Override
    public void run() {
        final JFrame   frame = new JFrame();
        final JPanel content = new JPanel(new BorderLayout());
        final JList     list = new JList(Tone.values());
        final JButton button = new JButton("Play");

        button.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent ae) {
                Object[] values = list.getSelectedValues();
                double[] chord  = new double[values.length];

                for(int i = 0; i < chord.length; ++i) {
                    Tone tone = (Tone)values[i];
                    chord[i]  = tone.hz;
                }

                JOptionPane.showMessageDialog(null,
                    "Chord selected: " + Arrays.toString(chord)
                );
            }
        });

        content.add(list, BorderLayout.CENTER);
        content.add(button, BorderLayout.SOUTH);

        frame.setContentPane(content);
        frame.pack();
        frame.setResizable(false);
        frame.setLocationRelativeTo(null);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
    }
}