我目前是高中生，正在当地大学攻读DE课程。我正在上Java课程，正在研究一个项目。
我仍然是初学者，正如您在我的代码中看到的那样，我正在尝试找到压缩代码的方法，以便我可以尝试添加更多内容。如果你能帮助我，我真的很感激！
该程序是针对不同长度单位的转换程序。我自学了组合框的基础知识，虽然我对它不是很熟悉。
我也无法弄清楚为什么转换按钮会延伸到目前为止。最后，我需要一个复选框，因为我真的不能想到它的另一个用途，我把它放在代码中，你会在代码中看到它。
注意：只是说;不要太复杂，我需要理解它，因为我必须解释在程序中做了什么
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Converter extends JFrame {
public static void main(String[] args) {
Converter myFrame = new Converter();
}
private JPanel myP1, myP2, myP3,myP4,myP5;
private JLabel myMessageLabel,myMessageLabel2,myMessageLabel3;
private JButton myButton;
private JComboBox myBox1,myBox2;
private JTextField myText;
private JCheckBox myCheck;
String combo1, combo2;
double inputNumber, convertedNumber;
char check;
public Converter() {
//Dimensions of Frame
final int W_WIDTH = 450;
final int W_HEIGHT = 200;
//Title of Window
setTitle("Unit Converter");
//Size is set
setSize(W_WIDTH, W_HEIGHT);
//Close operation
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//Set layout of frame
setLayout(new BorderLayout());
//Building and adding panels
buildPanel1();
add(myP1, BorderLayout.NORTH);
buildPanel2();
add(myP2, BorderLayout.CENTER);
buildPanel3();
buildPanel4();
add(myP4, BorderLayout.SOUTH);
buildPanel5();
myP2.add(myP5);
//Making the frame visible on the screen
setVisible(true);
}
private void buildPanel1() {
myMessageLabel = new JLabel("Welcome to the Master Creators Unit Converter!");
myP1 = new JPanel();
myP1.add(myMessageLabel);
}
private void buildPanel2() {
//First Combo Box
String[] units = { " ","Miles", "Feet", "Kilometers", "Meters" };
myP2 = new JPanel();
myBox1 = new JComboBox(units);
myBox1.addActionListener(new ComboBoxListener1());
myP2.add(myBox1);
}
private void buildPanel3() {
//Entering the value to be converted and check box
myP3 = new JPanel();
myMessageLabel3 = new JLabel("Enter a value:");
myText = new JTextField(10);
myCheck = new JCheckBox("Keep checked to convert!");
myCheck.addItemListener(new CheckBoxListener());
myP3.add(myMessageLabel3);
myP3.add(myText);
myP3.add(myCheck);
}
private void buildPanel4() {
//Button to convert
myButton = new JButton("Convert");
myButton.addActionListener(new myButtonListener());
myP4 = new JPanel();
myP4.setLayout(new GridLayout(2,1));
myP4.add(myP3);
myP4.add(myButton);
}
private void buildPanel5() {
//Second Combo Box
String[] units = { " ","Miles", "Feet", "Kilometers", "Meters" };
myP5 = new JPanel();
myMessageLabel2 = new JLabel("to");
myBox2 = new JComboBox(units);
myBox2.addActionListener(new ComboBoxListener2());
myP5.add(myMessageLabel2);
myP5.add(myBox2);
}
private class ComboBoxListener1 implements ActionListener {
public void actionPerformed (ActionEvent e) {
//Giving values to the different selections in the combo box
String selection = (String) myBox1.getSelectedItem();
if (selection.equals("Miles")) {
combo1 = "a";
}
else if (selection.equals("Feet")) {
combo1 = "b";
}
else if (selection.equals("Kilometers")) {
combo1 = "c";
}
else if (selection.equals("Meters")) {
combo1 = "d";
}
else {
combo1 = "z";
}
}
}
private class ComboBoxListener2 implements ActionListener {
public void actionPerformed (ActionEvent e) {
//Giving values to the different selections in the combo box
String selection = (String) myBox2.getSelectedItem();
if (selection.equals("Miles")) {
combo2 = "a";
}
else if (selection.equals("Feet")) {
combo2 = "b";
}
else if (selection.equals("Kilometers")) {
combo2 = "c";
}
else if (selection.equals("Meters")) {
combo2 = "d";
}
else {
combo2 = "z";
}
}
}
private class myButtonListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
String input;
//Obtains value entered by user and converts to double
input = myText.getText();
inputNumber = Double.parseDouble(input);
//Checks if the check box is checked before continuing
if(check == 'y') {
//Converts the value from the selected unit to the unit to convert to
if(combo1.equals(combo2)) {
JOptionPane.showMessageDialog(null, inputNumber);
}
else if (combo1 == "a" && combo2 == "b") {
convertedNumber = inputNumber * 5280;
JOptionPane.showMessageDialog(null, convertedNumber + " feet");
}
else if (combo1 == "a" && combo2 == "c") {
convertedNumber = inputNumber * 1.60934;
JOptionPane.showMessageDialog(null, convertedNumber + " kilometers");
}
else if (combo1 == "a" && combo2 == "d") {
convertedNumber = inputNumber * 1609.34;
JOptionPane.showMessageDialog(null, convertedNumber + " meters");
}
else if (combo1 == "b" && combo2 == "a") {
convertedNumber = inputNumber * 0.000189394;
JOptionPane.showMessageDialog(null, convertedNumber + " miles");
}
else if (combo1 == "b" && combo2 == "c") {
convertedNumber = inputNumber * 0.0003048;
JOptionPane.showMessageDialog(null, convertedNumber + " kilometers");
}
else if (combo1 == "b" && combo2 == "d") {
convertedNumber = inputNumber * 0.3048;
JOptionPane.showMessageDialog(null, convertedNumber + " meters");
}
else if (combo1 == "c" && combo2 == "a") {
convertedNumber = inputNumber * 0.621371;
JOptionPane.showMessageDialog(null, convertedNumber + " miles");
}
else if (combo1 == "c" && combo2 == "b") {
convertedNumber = inputNumber * 3280.84;
JOptionPane.showMessageDialog(null, convertedNumber + " feet");
}
else if (combo1 == "c" && combo2 == "d") {
convertedNumber = inputNumber * 1000;
JOptionPane.showMessageDialog(null, convertedNumber + " meters");
}
else if (combo1 == "d" && combo2 == "a") {
convertedNumber = inputNumber * 0.000621371;
JOptionPane.showMessageDialog(null, convertedNumber + " miles");
}
else if (combo1 == "d" && combo2 == "b") {
convertedNumber = inputNumber * 3.28084;
JOptionPane.showMessageDialog(null, convertedNumber + " feet");
}
else if (combo1 == "d" && combo2 == "c") {
convertedNumber = inputNumber * 0.001;
JOptionPane.showMessageDialog(null, convertedNumber + " kilometers");
}
}
}
}
private class CheckBoxListener implements ItemListener {
public void itemStateChanged (ItemEvent e) {
//Checks if the check box is checked
if (myCheck.isSelected()){
check = 'y';
}
else {
check = 'n';
}
}
}
}
答案 0 :(得分：1)
如果您的主要目标是使您的代码更整洁，更明确，那么我建议从以下开始：将您的单位数据类型从字符串转换为Java enum并封装您的距离一个Distance课程。这将带来以下好处：
combo1和combo2 if，else if语句以下是您可以使用的潜在结构示例：
public enum Unit {
MILES (1609.344),
FEET (0.3048),
KILOMETRES (1000.0),
METRES (1.0);
private final float toMetreRate;
Unit(float toMetreRate) {
this.toMetreRate = toMetreRate;
}
public float convertTo(float value, Unit unit) {
return value * toMetreRate / unit.toMetreRate;
}
}
public class Distance {
private final Unit unit;
private final float value;
public Distance(float value, Unit unit) {
this.value = value;
this.unit = unit;
}
public Distance convert(Unit newUnit) {
return new Distance(unit.covertTo(value, newUnit), newUnit);
}
}
答案 1 :(得分：0)
我将创建一个枚举，该枚举具有转换常量以及要与仪表转换的代码：
public enum Measure {
METERS("meters", 1.0),
KILOMETERS("kilometers", 1000),
FEET("feet", 0.3048),
MILES("miles", 1609.344);
private String text;
private double conversionConst;
private Measure(String text, double conversionConst) {
this.text = text;
this.conversionConst = conversionConst;
}
public String getText() {
return text;
}
@Override
public String toString() {
return text;
}
public double getConversionConst() {
return conversionConst;
}
public double toMeter(double value) {
return value * conversionConst;
}
public double fromMeter(double value) {
return value / conversionConst;
}
}
并使用此枚举创建组合框：
private JComboBox<Measure> fromCombo = new JComboBox<>(Measure.values());
private JComboBox<Measure> toCombo = new JComboBox<>(Measure.values());
在动作监听器中，使用以下方法：
String inputText = inputField.getText().trim();
try {
double input = Double.parseDouble(inputText);
Measure fromMeasure = (Measure) fromCombo.getSelectedItem();
Measure toMeasure = (Measure) toCombo.getSelectedItem();
double meter = fromMeasure.toMeter(input);
double result = toMeasure.fromMeter(meter);
String resultText = String.format("%.02f", result);
resultField.setText(resultText);
}
例如：
import java.awt.event.KeyEvent;
import javax.swing.*;
public class Converter2 extends JPanel {
private JComboBox<Measure> fromCombo = new JComboBox<>(Measure.values());
private JComboBox<Measure> toCombo = new JComboBox<>(Measure.values());
private JTextField inputField = new JTextField(10);
private JTextField resultField = new JTextField(10);
private JButton calculateButton = new JButton("Calculate");
public Converter2() {
calculateButton.setMnemonic(KeyEvent.VK_C);
calculateButton.addActionListener(e -> calculate());
resultField.setFocusable(false);
add(createTitleWrapper(inputField, "Input"));
add(createTitleWrapper(fromCombo, "From"));
add(createTitleWrapper(toCombo, "To"));
add(createTitleWrapper(resultField, "Result"));
add(calculateButton);
}
private void calculate() {
String inputText = inputField.getText().trim();
try {
double input = Double.parseDouble(inputText);
Measure fromMeasure = (Measure) fromCombo.getSelectedItem();
Measure toMeasure = (Measure) toCombo.getSelectedItem();
double meter = fromMeasure.toMeter(input);
double result = toMeasure.fromMeter(meter);
String resultText = String.format("%.02f", result);
resultField.setText(resultText);
} catch (NumberFormatException e) {
// e.printStackTrace();
// display warning JOptionPane
inputField.setText("");
inputField.requestFocusInWindow();
}
}
// creates a border with a title around a component
private JComponent createTitleWrapper(JComponent component, String title) {
JPanel wrapperPanel = new JPanel();
wrapperPanel.add(component);
wrapperPanel.setBorder(BorderFactory.createTitledBorder(title));
return wrapperPanel;
}
private static void createAndShowGui() {
Converter2 mainPanel = new Converter2();
JFrame frame = new JFrame("Converter2");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> createAndShowGui());
}
}