我已经添加这个程序有一段时间了，现在慢慢地从一个简单的计算器开发它，但现在该程序没有错误，但没有给我想要的输出。它应该将颜色更改为蓝色，但不会。我添加了 resultPane.setForeground(Color.BLUE);但不会更新 JLabel
public class TestCalculator {
private ResultPane resultPane;
public static void main(String[] args) {
new TestCalculator();
}
public TestCalculator() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
resultPane = new ResultPane();
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Testing");
frame.setGlassPane(resultPane);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new CalculatorPane(resultPane));
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class ResultPane extends JPanel {
private JLabel result;
private Timer timer;
private int xDelta = (Math.random() > 0.5) ? 1 : -1;
private int yDelta = (Math.random() > 0.5) ? 1 : -1;
public ResultPane() {
setOpaque(false);
setLayout(null);
result = new JLabel();
Font font = result.getFont();
font = font.deriveFont(Font.BOLD, 26f);
result.setFont(font);
add(result);
HandlerClass handler = new HandlerClass();
result.addMouseListener(handler);
result.addMouseMotionListener(handler);
timer = new Timer(40, new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
Point point = result.getLocation();
point.x += xDelta;
point.y += yDelta;
if (point.x < 0) {
point.x = 0;
xDelta *= -1;
} else if (point.x + result.getWidth() > getWidth()) {
point.x = getWidth() - result.getWidth();
xDelta *= -1;
}
if (point.y < 0) {
point.y = 0;
yDelta *= -1;
} else if (point.y + result.getHeight() > getHeight()) {
point.y = getHeight() - result.getHeight();
yDelta *= -1;
}
result.setLocation(point);
repaint();
}
});
timer.start();
}
public void setResult(Number number) {
result.setText(NumberFormat.getNumberInstance().format(number));
result.setSize(result.getPreferredSize());
setVisible(true);
}
public String getResultText() {
return result.getText();
}
}
public class CalculatorPane extends JPanel {
private final ResultPane resultPane;
private final JLabel firstNumberLabel = new JLabel("First Number:");
private final JLabel secondNumberLabel = new JLabel("Second Number:");
private final JTextField firstNumberField = new JTextField(5);
private final JTextField secondNumberField = new JTextField(5);
public double result = 0.0;
public CalculatorPane(ResultPane resultPane) {
setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridwidth = GridBagConstraints.REMAINDER;
this.resultPane = resultPane;
JPanel fields = new JPanel();
fields.add(firstNumberLabel);
fields.add(firstNumberField);
fields.add(secondNumberLabel);
fields.add(secondNumberField);
add(fields, gbc);
JPanel buttons = new JPanel();
buttons.add(new JButton(new AddAction()));
buttons.add(new JButton(new SubtractAction()));
buttons.add(new JButton(new MultiplyAction()));
buttons.add(new JButton(new DivideAction()));
add(buttons, gbc);
}
public class AddAction extends AbstractAction {
public AddAction() {
putValue(NAME, "+");
}
@Override
public void actionPerformed(ActionEvent e) {
try {
double num1 = Double.parseDouble(firstNumberField.getText());
double num2 = Double.parseDouble(secondNumberField.getText());
double result = num1 + num2;
resultPane.setResult(result);
String resultText = resultPane.getResultText();
firstNumberField.setText(resultText);
} catch (NumberFormatException exp) {
}
}
}
public class SubtractAction extends AbstractAction {
public SubtractAction() {
putValue(NAME, "-");
}
@Override
public void actionPerformed(ActionEvent e) {
try {
double num1 = Double.parseDouble(firstNumberField.getText());
double num2 = Double.parseDouble(secondNumberField.getText());
double result = num1 - num2;
resultPane.setResult(result);
String resultText = resultPane.getResultText();
firstNumberField.setText(resultText);
} catch (NumberFormatException exp) {
}
}
}
public class MultiplyAction extends AbstractAction {
public MultiplyAction() {
putValue(NAME, "x");
}
@Override
public void actionPerformed(ActionEvent e) {
try {
double num1 = Double.parseDouble(firstNumberField.getText());
double num2 = Double.parseDouble(secondNumberField.getText());
double result = num1 * num2;
resultPane.setResult(result);
String resultText = resultPane.getResultText();
firstNumberField.setText(resultText);
} catch (NumberFormatException exp) {
}
}
}
public class DivideAction extends AbstractAction {
public DivideAction() {
putValue(NAME, "/");
}
@Override
public void actionPerformed(ActionEvent e) {
try {
double num1 = Double.parseDouble(firstNumberField.getText());
double num2 = Double.parseDouble(secondNumberField.getText());
double result = num1 / num2;
resultPane.setResult(result);
String resultText = resultPane.getResultText();
firstNumberField.setText(resultText);
} catch (NumberFormatException exp) {
}
}
}
}
private class HandlerClass implements MouseListener, MouseMotionListener {
public void mouseClicked(MouseEvent event) {
resultPane.setForeground(Color.BLUE);
}
public void mouseReleased(MouseEvent event) {
}
public void mousePressed(MouseEvent event) {
}
public void mouseExited(MouseEvent event) {
}
public void mouseEntered(MouseEvent event) {
}
public void mouseMoved(MouseEvent event) {
}
public void mouseDragged(MouseEvent event){
}
}
}
最佳答案
在 MouseListener 中，您设置的是 JPanel 的前景色，而不是 JLabel 的前景色:
public void mouseClicked(MouseEvent event) {
resultPane.setForeground(Color.BLUE); // This is the problem
}
resultPane 是您的自定义 JPanel。您需要更改它设置此自定义面板中包含的 JLabel 的前景色。我只需向 ResultPane 添加一个方法，如下所示:
public void setLabelForeground(Color color) {
result.setForeground(color);
}
然后在 MouseListener 中调用 resultPane.setLabelForeground(Color.BLUE);。
另外，不确定这是否是您想要做的，但这仍然只会在您单击 JLabel 时更改前景色...？
关于java - JLabel 不改变 MouseEvent 的颜色？ java ，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/23748437/