出于清楚和其他原因，我会避免将课程设为implements ActionListener。只需为每个JComboBox 添加一个匿名ActionListener。像这样的
JComboBox comboFont;
JLabel label = new JLabel("label");
String fontString = "ariel";
int fontWeight = Font.PLAIN;
int fontSize = 16;
Font font = new Font(fontString, fontWeight, fontSize);
Color textColor = Color.BLACK
public JPanel contentPane() {
comboFont = new JComboBox(fontStrings);
comboFont.addActionListener(new ActionListener(){
@Override
public void actionPerformed(ActionEvent e) {
fontString = (String)comboFont.getSelectedItem();
font = new Font(fontString, fontWeight, fontSize);
label.setFont(font);
}
});
}
这将在从组合框中选择新字体时动态更改字体。您应该拥有Font、fontSize 和fontWeight 的全局值，以便每个不同的组合框都可以使用它们并在actionPerformed 中相应地更改字体
另外，看看this answer from AndrewThompson，在JComboBox 中显示了实际渲染的字体样式，所有字体都是从系统字体中获取的。这是一瞥。不要忘记在链接中为答案投票！
试试这个。我修改了你的代码
import java.awt.event.*;
import javax.swing.*;
import java.awt.*;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
public class textchanger {
//String[] fontStrings = {"Arial", "Arial Black", "Helvetica", "Impact", "Times New Roman"};
Integer[] fontSizes = {10, 12, 14, 16, 18, 20, 22, 24};
String[] colorStrings = {"Red", "Blue", "Green", "Yellow", "Orange"};
String[] bgStrings = {"Red", "Blue", "Green", "Yellow", "Orange"};
String[] fontStyle = {"BOLD", "Italic", "Plain"};
JPanel panel;
JLabel labelText, labelFont, labelSize, labelColor, labelBG, labelOutput;
JTextField textField;
JComboBox comboFont, comboSize, comboColor, comboBG;
JButton btnOk, btnCancel;
String fontString;
int fontWeight = Font.PLAIN;
int fontSize;
Font font = new Font(fontString, Font.PLAIN, fontSize);
Color textColor;
Color bgColor;
static String text = "Text";
static JLabel textLabel = new JLabel(text);
JPanel textLabelPanel = new JPanel(new GridBagLayout());
public JPanel contentPane() { //Creates the GUI
panel = new JPanel();
panel.setLayout(new GridLayout(7, 8, 10, 10));
textLabelPanel.setPreferredSize(new Dimension(500, 50));
labelText = new JLabel("Enter Text:");
textField = new JTextField(10);
textField.setText(text);
textField.getDocument().addDocumentListener(new DocumentListener() {
@Override
public void insertUpdate(DocumentEvent e) {
String newText = textField.getText();
textLabel.setText(newText);
}
@Override
public void removeUpdate(DocumentEvent e) {
String newText = textField.getText();
textLabel.setText(newText);
}
@Override
public void changedUpdate(DocumentEvent e) {
}
});
labelFont = new JLabel("Select font type:");
GraphicsEnvironment ge = GraphicsEnvironment.
getLocalGraphicsEnvironment();
String[] fonts = ge.getAvailableFontFamilyNames();
comboFont = new JComboBox(fonts);
fontString = (String) comboFont.getItemAt(0);
comboFont.setSelectedIndex(0);
comboFont.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
fontString = (String) comboFont.getSelectedItem();
font = new Font(fontString, fontWeight, fontSize);
textLabel.setFont(font);
}
});
labelSize = new JLabel("Select font size:");
comboSize = new JComboBox(fontSizes);
comboSize.setSelectedIndex(0);
fontSize = (Integer) comboSize.getItemAt(0);
comboSize.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
fontSize = (Integer) comboSize.getSelectedItem();
font = new Font(fontString, fontWeight, fontSize);
textLabel.setFont(font);
}
});
labelColor = new JLabel("Select font color:");
comboColor = new JComboBox(colorStrings);
comboColor.setSelectedIndex(0);
textColor = Color.RED;
textLabel.setForeground(textColor);
comboColor.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
String colorString = (String) comboColor.getSelectedItem();
switch (colorString) {
case "Red":
textColor = Color.RED;
break;
case "Blue":
textColor = Color.BLUE;
break;
case "Green":
textColor = Color.GREEN;
break;
case "Yellow":
textColor = Color.YELLOW;
break;
case "Orange":
textColor = Color.ORANGE;
break;
default:
textColor = Color.RED;
}
textLabel.setForeground(textColor);
}
});
labelBG = new JLabel("Select a background color:");
comboBG = new JComboBox(bgStrings);
comboBG.setSelectedIndex(1);
bgColor = Color.BLUE;
textLabelPanel.setBackground(bgColor);
comboBG.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
String bgColorString = (String) comboBG.getSelectedItem();
switch (bgColorString) {
case "Red":
bgColor = Color.RED;
break;
case "Blue":
bgColor = Color.BLUE;
break;
case "Green":
bgColor = Color.GREEN;
break;
case "Yellow":
bgColor = Color.YELLOW;
break;
case "Orange":
bgColor = Color.ORANGE;
break;
default:
bgColor = Color.RED;
}
textLabelPanel.setBackground(bgColor);
}
});
btnOk = new JButton("Ok");
btnCancel = new JButton("Cancel");
labelOutput = new JLabel("");
panel.add(labelText);
panel.add(textField);
panel.add(labelFont);
panel.add(comboFont);
panel.add(labelSize);
panel.add(comboSize);
panel.add(labelColor);
panel.add(comboColor);
panel.add(labelBG);
panel.add(comboBG);
panel.add(btnOk);
panel.add(btnCancel);
panel.add(labelOutput);
JPanel mainPanel = new JPanel(new BorderLayout());
mainPanel.add(panel);
textLabelPanel.add(textLabel);
mainPanel.add(textLabelPanel, BorderLayout.SOUTH);
return mainPanel;
}
class FontCellRenderer extends DefaultListCellRenderer {
public Component getListCellRendererComponent(
JList list,
Object value,
int index,
boolean isSelected,
boolean cellHasFocus) {
JLabel label = (JLabel) super.getListCellRendererComponent(
list, value, index, isSelected, cellHasFocus);
Font font = new Font((String) value, Font.PLAIN, 20);
label.setFont(font);
return label;
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
JFrame frame = new JFrame("Fonts, Colors and Sizes");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(650, 350);
textchanger txtObj = new textchanger();
frame.setContentPane(txtObj.contentPane());
frame.setVisible(true);
}
});
}
}