Java Currency Converter GUI

Question

我正在尝试制作一个简单的Java货币转换器GUI。 到目前为止，我有这个：（4个部分）

如何设置jcombbox中每个项目的值（例如每种货币），以便可以使用它们来计算转换？

这是第一部分（1个组合框）：

import java.awt.*;
import java.awt.event.*; 
import javax.swing.*;
public class test extends JPanel
{
private JPanel panel;
private JLabel messageLabel;
private JTextField USDTextField;
private JPanel CurrencyPanel;         
private JComboBox CurrencyBox;       
private String[] Currency  = { "USD - United States Dollar",
                 "GBP - Great Britain Pound", "AUD - Australian Dollar",
                 "EUR- Euro"};
public currency1()
{
  setLayout(new BorderLayout(4,1));
  buildCurrencyPanel();
  add(CurrencyPanel, BorderLayout.CENTER);
  setVisible(true);
  setBorder(BorderFactory.createTitledBorder("Select currency"));

}
private void buildCurrencyPanel()
{
  CurrencyPanel = new JPanel();
  CurrencyBox = new JComboBox(Currency);
  CurrencyPanel.add(CurrencyBox);
}
 public static void main(String[] args)
{
   new currency1();
}
}

Answer 1

也许尝试使用Map（例如HashMap）而不是数组？ 密钥将是货币名称，值将是货币的值。 所以代替：

private String[] Currency  = { "USD - United States Dollar",
                 "GBP - Great Britain Pound", "AUD - Australian Dollar",
                 "EUR- Euro"};

我会做到的：

private Map<String, Double> Currency = new HashMap<>();
//This is an initialization block
{
   Currency.put("USD - United States Dollar", 4.44);
   Currency.put("GBP - Great Britain Pound", 5.55);
   //and so on...
}

Answer 2

只有评论，我对Currency Converter的看法

1. 货币对的定义，默认情况下存在基础货币和可变货币

2. 岩心率的定义

3. 买卖定义

4. 基本/变量的定义

5. （将所有上午的积分放在一起），然后有四种可能的组合

   • 购买基数（EUR 1,000.- at 1.31）

   • 卖出基础（1,000欧元-1.31）

   • 购买Variable（USD 1,000.- at 1.311）

   • 卖出变量（1,000美元-在1.311时）

6. 英镑/美元有反向计算方法

Answer 3

可能解决方案的建议：

• 我将创建一个Currency类，该类具有一个String currencyName字段和一个double currencyRate字段，该字段保存与某些标准相比的汇率。
• 我将用Currency对象填充我的JComboBox模型。
• 我给JCOmboBox一个单元格渲染器，以便它显示货币名称。
• 我给我的GUI一个“转换” JButton
• 在该按钮的操作中，我将通过调用getSelectedItem()从两个组合框中提取所选货币，并将使用它们来计算答案。
• 在尝试计算之前，请确保所有选定项目都不为空。
• 或通过添加到两个组合框的ActionListener来完成此操作，但是我首先必须确保所选值不为null或所选索引不为-1。

Answer 4

创建一个包含双精度值的Currency类，该双精度值是货币的值（您选择如何计算它们）。

让货币的toString()返回组合框中应显示的内容，例如“ USD-United States Dollar”。

现在确保您的JComboBox使用泛型，因此当您调用getSelectedItem() ，不必像new JComboBox<Currency>()一样将其转换为Currency 。 如果您已经在Java 6上设置了项目，那么即使Java 7中添加了通用类型的JComboBox泛型，也是因为某些所谓的类型擦除的原因。 查找详细信息。

Answer 5

我单击您提供的URL并没有看到太多，所以我很确定这是否完全合适，但是通常使用Java enum可以最好地解决此类问题。 特别是，您可以使用类似以下内容的方式来存储转化字符串和转化率（请注意，我选择了任意转化率-用实际转化率代替这些转化率）：

public enum Currency {
    USD(1.0,"United States Dollar"),
    GPB(0.9,"Great Britain Pound"),
    AUD(0.8,"Australian Dollar"),
    EUR(0.7,"Euro");

    private double conversionRatio;
    private String description;

    private Currency(double conversionRatio, String description) {
        this.conversionRatio = conversionRatio;
        this.description = description;
    }

    public double getConversionRatio() {
        return conversionRatio;
    }

    public String getDescription() {
        return description;
    }

    public void toString() {
            return new StringBuilder(name()).append(" - ").append(getDescription()).toString();
    }

}

然后可以将它们添加到您的组合框中，如下所示：

for( Currency currency : Currency.values() ) {
     CurrencyBox.addItem(currency);
}

Answer 6

package convert;

public class CConverter extends javax.swing.JFrame {

    // Currency Values {Rupee,Dollar,Pound,Yen,Euro} 
double curr1[] = {0,1,0.015,0.012,1.67,0.014};
double curr2[] = {0,1,0.015,0.012,1.67,0.014}; 

/**
 * Creates new form CConverter
 */
public CConverter() {
    initComponents();
}

/**
 * This method is called from within the constructor to initialize the form.
 * WARNING: Do NOT modify this code. The content of this method is always
 * regenerated by the Form Editor.
 */
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">                          
private void initComponents() {

    jLabel1 = new javax.swing.JLabel();
    jcmbCurrency1 = new javax.swing.JComboBox<>();
    jcmbCurrency2 = new javax.swing.JComboBox<>();
    jtxtAmount = new javax.swing.JTextField();
    jlblConversion = new javax.swing.JLabel();
    jbtnConvert = new javax.swing.JButton();
    jbtnReset = new javax.swing.JButton();
    jtxtConversion = new javax.swing.JTextField();
    jbtnExit = new javax.swing.JButton();

    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

    jLabel1.setFont(new java.awt.Font("Tahoma", 1, 18)); // NOI18N
    jLabel1.setText("Currency Converter");

    jcmbCurrency1.setModel(new javax.swing.DefaultComboBoxModel<>(new String[] { "Choose One", "INDIA Rupee", "US Dollar", "UK Pound", "JAPAN Yen", "Euro" }));

    jcmbCurrency2.setModel(new javax.swing.DefaultComboBoxModel<>(new String[] { "Choose Other", "INDIA Rupee", "US Dollar", "UK Pound", "JAPAN Yen", "Euro" }));

    jtxtAmount.setText("Amount");

    jlblConversion.setText("Conversion");

    jbtnConvert.setText("CONVERT");
    jbtnConvert.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            jbtnConvertActionPerformed(evt);
        }
    });

    jbtnReset.setText("RESET");
    jbtnReset.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            jbtnResetActionPerformed(evt);
        }
    });

    jtxtConversion.setFont(new java.awt.Font("Tahoma", 1, 14)); // NOI18N
    jtxtConversion.setForeground(new java.awt.Color(0, 0, 204));
    jtxtConversion.setText("Converted Value");

    jbtnExit.setText("Exit");
    jbtnExit.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            jbtnExitActionPerformed(evt);
        }
    });

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(layout.createSequentialGroup()
            .addGap(0, 0, Short.MAX_VALUE)
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                .addComponent(jLabel1)
                .addGroup(layout.createSequentialGroup()
                    .addComponent(jbtnConvert)
                    .addGap(18, 18, 18)
                    .addComponent(jbtnReset, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
                .addComponent(jcmbCurrency1, 0, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addComponent(jcmbCurrency2, 0, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addComponent(jtxtAmount)
                .addComponent(jlblConversion, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addComponent(jtxtConversion))
            .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
        .addGroup(layout.createSequentialGroup()
            .addGap(158, 158, 158)
            .addComponent(jbtnExit)
            .addContainerGap(191, Short.MAX_VALUE))
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGroup(layout.createSequentialGroup()
            .addGap(22, 22, 22)
            .addComponent(jLabel1)
            .addGap(28, 28, 28)
            .addComponent(jcmbCurrency1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addGap(18, 18, 18)
            .addComponent(jcmbCurrency2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addGap(18, 18, 18)
            .addComponent(jtxtAmount, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addGap(38, 38, 38)
            .addComponent(jlblConversion)
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
            .addComponent(jtxtConversion, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
            .addGap(18, 18, 18)
            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                .addComponent(jbtnConvert)
                .addComponent(jbtnReset))
            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
            .addComponent(jbtnExit)
            .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
    );

    pack();
}// </editor-fold>                        

private void jbtnConvertActionPerformed(java.awt.event.ActionEvent evt) {                                            
    // TODO add your handling code here:


    double amt = Double.parseDouble(jtxtAmount.getText());

    int obj1 = jcmbCurrency1.getSelectedIndex();
    int obj2 = jcmbCurrency2.getSelectedIndex();

    if (obj1 == obj2){
        String samecur = "Both the currencies cannot be the same";
        jtxtConversion.setText(samecur);
    }
    else {
        double res = (amt/curr1[obj1])*curr2[obj2];

        String conv = String.format("%.2f",res);
        jtxtConversion.setText(conv);
    }

}                                           

private void jbtnResetActionPerformed(java.awt.event.ActionEvent evt) {                                          
    // TODO add your handling code here:
    jtxtAmount.setText(null);
    jtxtConversion.setText(null);
    jcmbCurrency1.setSelectedIndex(0);
    jcmbCurrency2.setSelectedIndex(0);
}                                         

private void jbtnExitActionPerformed(java.awt.event.ActionEvent evt) {                                         
    // TODO add your handling code here:
    System.exit(0);
}                                        

/**
 * @param args the command line arguments
 */
public static void main(String args[]) {
    /* Set the Nimbus look and feel */
    //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
    /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
     * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
     */
    try {
        for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
            if ("Nimbus".equals(info.getName())) {
                javax.swing.UIManager.setLookAndFeel(info.getClassName());
                break;
            }
        }
    } catch (ClassNotFoundException ex) {
        java.util.logging.Logger.getLogger(CConverter.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (InstantiationException ex) {
        java.util.logging.Logger.getLogger(CConverter.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (IllegalAccessException ex) {
        java.util.logging.Logger.getLogger(CConverter.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (javax.swing.UnsupportedLookAndFeelException ex) {
        java.util.logging.Logger.getLogger(CConverter.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    }
    //</editor-fold>

    /* Create and display the form */
    java.awt.EventQueue.invokeLater(new Runnable() {
        public void run() {
            new CConverter().setVisible(true);
        }
    });
}

// Variables declaration - do not modify                     
private javax.swing.JLabel jLabel1;
private javax.swing.JButton jbtnConvert;
private javax.swing.JButton jbtnExit;
private javax.swing.JButton jbtnReset;
private javax.swing.JComboBox<String> jcmbCurrency1;
private javax.swing.JComboBox<String> jcmbCurrency2;
private javax.swing.JLabel jlblConversion;
private javax.swing.JTextField jtxtAmount;
private javax.swing.JTextField jtxtConversion;
// End of variables declaration                   
}

试试这个代码我已经以印度卢比为基础，它可以转换印度卢比美元美元英镑日元日元欧元

Answer 7

基本上，我理解“ 汇率 ”的方式是，将一种货币兑换为另一种货币要花费多少钱。

对我来说，这意味着需要将一种货币与另一种货币联系起来。 这可以是“ 货币对 ”

除了某些先前的建议（例如，使用枚举）之外，还可以将与汇率相关的货币对用作蛮力进行转换。

例如（请注意，下面的代码将需要适当的验证和缩放/四舍五入）：

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.math.BigDecimal;
import java.text.NumberFormat;
import java.util.HashMap;
import java.util.Locale;
import java.util.Map;

import static javax.swing.JFrame.EXIT_ON_CLOSE;

public class Main extends JPanel {
    enum Currency {
        USD("United States Dollar"),
        GBR("Great Britain Pound"),
        AUD("Australian Dollar"),
        EUR("Euro");

        private String description;

        Currency(String description) {
            this.description = description;
        }

        @Override public String toString() {
            return this.name() + " - " + this.description;
        }
    }

    class CurrencyPair {
        private final Currency from;
        private final Currency to;

        public CurrencyPair(Currency from, Currency to) {
            this.from = from;
            this.to = to;
        }

        @Override public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;

            CurrencyPair that = (CurrencyPair) o;
            if (from != that.from) return false;
            return to == that.to;
        }

        @Override public int hashCode() {
            int result = from.hashCode();
            result = 31 * result + to.hashCode();
            return result;
        }
    }

    private final Map<CurrencyPair, BigDecimal> exchangeRates = new HashMap<CurrencyPair, BigDecimal>() {{
        put(new CurrencyPair(Main.Currency.USD, Main.Currency.USD), BigDecimal.valueOf(1));
        put(new CurrencyPair(Main.Currency.AUD, Main.Currency.AUD), BigDecimal.valueOf(1));
        put(new CurrencyPair(Main.Currency.EUR, Main.Currency.EUR), BigDecimal.valueOf(1));
        put(new CurrencyPair(Main.Currency.GBR, Main.Currency.GBR), BigDecimal.valueOf(1));

        put(new CurrencyPair(Main.Currency.USD, Main.Currency.GBR), BigDecimal.valueOf(0.75));
        put(new CurrencyPair(Main.Currency.USD, Main.Currency.AUD), BigDecimal.valueOf(1.33));
        put(new CurrencyPair(Main.Currency.USD, Main.Currency.EUR), BigDecimal.valueOf(0.89));

        put(new CurrencyPair(Main.Currency.EUR, Main.Currency.USD), BigDecimal.valueOf(1.12));
        put(new CurrencyPair(Main.Currency.EUR, Main.Currency.AUD), BigDecimal.valueOf(1.49));
        put(new CurrencyPair(Main.Currency.EUR, Main.Currency.GBR), BigDecimal.valueOf(0.85));

        put(new CurrencyPair(Main.Currency.AUD, Main.Currency.USD), BigDecimal.valueOf(0.74));
        put(new CurrencyPair(Main.Currency.AUD, Main.Currency.EUR), BigDecimal.valueOf(0.67));
        put(new CurrencyPair(Main.Currency.AUD, Main.Currency.GBR), BigDecimal.valueOf(0.57));

        put(new CurrencyPair(Main.Currency.GBR, Main.Currency.USD), BigDecimal.valueOf(1.33));
        put(new CurrencyPair(Main.Currency.GBR, Main.Currency.EUR), BigDecimal.valueOf(1.18));
        put(new CurrencyPair(Main.Currency.GBR, Main.Currency.AUD), BigDecimal.valueOf(1.76));

    }};

    public Main() {
        super(new FlowLayout(FlowLayout.LEADING));

        // Amount
        JTextField amountInput = new JTextField(20);
        JPanel amount = new JPanel();
        amount.add(amountInput);
        amount.setBorder(BorderFactory.createTitledBorder("Enter Ammount"));
        add(amount, BorderLayout.CENTER);

        // From
        JPanel from = new JPanel();
        JComboBox fromOptions = new JComboBox(Currency.values());
        from.add(fromOptions);
        from.setBorder(BorderFactory.createTitledBorder("Select currency"));
        add(from, BorderLayout.CENTER);

        // To
        JComboBox toOptions = new JComboBox(Currency.values());
        JPanel to = new JPanel();
        to.add(toOptions);
        to.setBorder(BorderFactory.createTitledBorder("Convert to"));
        add(to, BorderLayout.CENTER);

        // Convert Action
        JLabel convertText = new JLabel();
        JButton convertCmd = new JButton("Convert");
        convertCmd.addActionListener(convertAction(amountInput, fromOptions, toOptions, convertText));
        JPanel convert = new JPanel();
        convert.add(convertCmd);
        convert.add(convertText);
        add(convert);
    }

    private ActionListener convertAction(
            final JTextField amountInput,
            final JComboBox fromOptions,
            final JComboBox toOptions,
            final JLabel convertText) {

        return new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                // TODO: Needs proper validation
                String amountInputText = amountInput.getText();
                if ("".equals(amountInputText)) { return; }

                // Convert
                BigDecimal conversion = convertCurrency(amountInputText);
                convertText.setText(NumberFormat
                        .getCurrencyInstance(Locale.US)
                        .format(conversion));
            }

            private BigDecimal convertCurrency(String amountInputText) {
                // TODO: Needs proper rounding and precision setting
                CurrencyPair currencyPair = new CurrencyPair(
                        (Currency) fromOptions.getSelectedItem(),
                        (Currency) toOptions.getSelectedItem());
                BigDecimal rate = exchangeRates.get(currencyPair);
                BigDecimal amount = new BigDecimal(amountInputText);
                return amount.multiply(rate);
            }
        };
    }


    public static void main(String[] args) {
        JFrame frame = new JFrame();
        frame.getContentPane().add(new Main());
        frame.setTitle("Currency Thing");
        frame.setSize(500, 500);
        frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }


}