我有这个计算器，但我不知道如何获取其中的值resultpane单击“完成”按钮时到第一个文本框。
我是 Java 新手。我已经尝试这样做，但我一直收到错误。
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.NumberFormat;
import javax.swing.AbstractAction;
import static javax.swing.Action.NAME;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class TestCalculator {
public static void main(String[] args) {
new TestCalculator();
}
public TestCalculator() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
ResultPane resultPane = new ResultPane();
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);
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("Result: " + NumberFormat.getNumberInstance().format(number));
result.setSize(result.getPreferredSize());
setVisible(true);
}
}
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 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()));
buttons.add(new JButton(new ToText1Action()));
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;
//num1.setResult(firstNumberField);
resultPane.setResult(result);
} 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);
} 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);
} 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);
} catch (NumberFormatException exp) {
}
}
}
public class ToText1Action extends AbstractAction {
public ToText1Action() {
putValue(NAME, "Finish");
}
@Override
public void actionPerformed(ActionEvent e) {
try {
//i would like to put it here
} catch (NumberFormatException exp) {
}
}
}
}
}
为您的 ResultPane 提供一个新的公共方法，允许您从其 JLabel 中提取文本，如下所示：
public String getResultText() {
return result.getText();
}
然后当您想要获取该字段的文本时调用它：
public class ToText1Action extends AbstractAction {
public ToText1Action() {
putValue(NAME, "Finish");
}
@Override
public void actionPerformed(ActionEvent e) {
String resultText = resultPane.getResultText();
double number = // extract number from resultText
firstNumberField.setText(number);
}
}
更好的是，只需将最新结果值存储在作为类的实例字段的双变量中，例如称为lastResult并用它设置第一个数字字段。
请注意，不应有空的 catch 块。
Edit
例如：
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);
private double result = 0.0; // ****** declared here
// ***** etc..... *****
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());
result = num1 / num2; // ****** note variable not declared
resultPane.setResult(result);
} catch (NumberFormatException exp) {
// show error message
// set text fields to "0"
}
}
}
public class ToText1Action extends AbstractAction {
public ToText1Action() {
super("Finish");
putValue(MNEMONIC_KEY, KeyEvent.VK_F);
}
@Override
public void actionPerformed(ActionEvent e) {
firstNumberField.setText(String.format("%.2f", result));
}
}
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