CurrencyConverter.java

import java.awt.Color;
import javax.swing.JOptionPane;
public class CurrencyConverter extends javax.swing.JFrame {
    double US_Dollar = 1.25;
    double Indian_Rupee = 103.56;
    double Brazilian_Real = 6.22;
    double Canadian_Dollar = 1.71;
    double Kenyan_Shilling = 182.54;
    double Indonesian_Rupiah = 19168.34;
    double Nigerian_Naira = 985.45;
    double Philippine_Peso = 70.77;
    double Pakistani_Rupee = 382.34;
    
    String[] currencyUnits = {"Units","US Dollar","Indian Rupee","Brazilian Real","Canadian Dollar","Kenyan Shilling","Indonesian Rupiah","Nigerian Naira","Philippine Peso","Paskistani Rupee"};
        public CurrencyConverter() {
            initComponents();
        }
        private void initComponents(){
            jPanel1 = new javax.swing.JPanel();
            jLabel1 = new javax.swing.JLabel();
            firstCountry = new javax.swing.JComboBox<>();
            secondCountry = new javax.swing.JComboBox<>();
            jLabel2 = new javax.swing.JLabel();
            jLabel3 = new javax.swing.JLabel();
            t1 = new javax.swing.JTextField();
            t2 = new javax.swing.JTextField();
            jButton1 = new javax.swing.JButton();
            jButton1.setBackground(Color.green);;
            jButton2 = new javax.swing.JButton();
            jButton2.setBackground(Color.orange);
            jButton3 = new javax.swing.JButton();
            jButton3.setBackground(Color.red);
            jButton3.setForeground(Color.white);
            secondCurrencyUnit = new javax.swing.JLabel();
            firstCurrencyUnit = new javax.swing.JLabel();
    
            setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
            jPanel1.setBackground(Color.LIGHT_GRAY);
            jLabel1.setFont(new java.awt.Font("Tahoma", 1, 24));
            jLabel1.setText("CURRENCT CONVERTER");
    
            firstCountry.setFont(new java.awt.Font("Tahoma", 1, 18));
            firstCountry.setModel(new javax.swing.DefaultComboBoxModel<>(new String[] { "Choose One...", "USA", "India", "Brazil", "Canada", "Kenyan", "Indonesia", "Nigeria", "Philippine", "Pakistan" }));
            firstCountry.addItemListener(new java.awt.event.ItemListener() {
                public void itemStateChanged(java.awt.event.ItemEvent evt) {
                    firstCountryItemStateChanged(evt);
                }
            });
            secondCountry.setFont(new java.awt.Font("Tahoma", 1, 18));
            secondCountry.setModel(new javax.swing.DefaultComboBoxModel<>(new String[] { "Choose One...", "USA", "India", "Brazil", "Canada", "Kenyan", "Indonesia", "Nigeria", "Philippine", "Pakistan" }));
            secondCountry.addItemListener(new java.awt.event.ItemListener() {
                public void itemStateChanged(java.awt.event.ItemEvent evt) {
                    secondCountryItemStateChanged(evt);
                }
            });
            jLabel2.setFont(new java.awt.Font("Tahoma", 1, 15));
            jLabel2.setText("From currency");
    
            jLabel3.setFont(new java.awt.Font("Tahoma", 1, 15));
            jLabel3.setText("To currency");
    
            t1.setFont(new java.awt.Font("Tahoma", 1, 18));
    
            t2.setFont(new java.awt.Font("Tahoma", 1, 18));
    
            jButton1.setFont(new java.awt.Font("Tahoma", 1, 18));
            jButton1.setText("Convert Currency");
            jButton1.addActionListener(new java.awt.event.ActionListener() {
                public void actionPerformed(java.awt.event.ActionEvent evt) {
                    jButton1ActionPerformed(evt);
                }
            });
    
            jButton2.setFont(new java.awt.Font("Tahoma", 1, 18));
            jButton2.setText("Reset");
            jButton2.addActionListener(new java.awt.event.ActionListener() {
                public void actionPerformed(java.awt.event.ActionEvent evt) {
                    jButton2ActionPerformed(evt);
                }
            });
    
            jButton3.setFont(new java.awt.Font("Tahoma", 1, 18));
            jButton3.setText("Exit");
            jButton3.addActionListener(new java.awt.event.ActionListener() {
                public void actionPerformed(java.awt.event.ActionEvent evt) {
                    jButton3ActionPerformed(evt);
                }
            });
    
            secondCurrencyUnit.setFont(new java.awt.Font("Tahoma", 1, 14));
            secondCurrencyUnit.setHorizontalAlignment(javax.swing.SwingConstants.RIGHT);
            secondCurrencyUnit.setText("units");
    
            firstCurrencyUnit.setFont(new java.awt.Font("Tahoma", 1, 14));
            firstCurrencyUnit.setHorizontalAlignment(javax.swing.SwingConstants.RIGHT);
            firstCurrencyUnit.setText("units");
    
            javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
            jPanel1.setLayout(jPanel1Layout);
            jPanel1Layout.setHorizontalGroup(
                jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
                    .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                    .addComponent(jLabel1)
                    .addGap(290, 290, 290))
                .addGroup(jPanel1Layout.createSequentialGroup()
                    .addGap(93, 93, 93)
                    .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                        .addComponent(jButton1)
                        .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                            .addComponent(firstCountry, 0, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                            .addComponent(t1)
                            .addComponent(jLabel2, javax.swing.GroupLayout.PREFERRED_SIZE, 131, javax.swing.GroupLayout.PREFERRED_SIZE)
                            .addComponent(firstCurrencyUnit, javax.swing.GroupLayout.DEFAULT_SIZE, 277, Short.MAX_VALUE)))
                    .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                        .addGroup(jPanel1Layout.createSequentialGroup()
                            .addGap(81, 81, 81)
                            .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                                .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                                    .addComponent(jLabel3)
                                    .addComponent(secondCountry, 0, 272, Short.MAX_VALUE)
                                    .addComponent(t2))
                                .addComponent(secondCurrencyUnit, javax.swing.GroupLayout.PREFERRED_SIZE, 277, javax.swing.GroupLayout.PREFERRED_SIZE)))
                        .addGroup(jPanel1Layout.createSequentialGroup()
                            .addGap(11, 11, 11)
                            .addComponent(jButton2)
                            .addGap(94, 94, 94)
                            .addComponent(jButton3)))
                    .addContainerGap(114, Short.MAX_VALUE))
            );
            jPanel1Layout.setVerticalGroup(
                jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGroup(jPanel1Layout.createSequentialGroup()
                    .addContainerGap()
                    .addComponent(jLabel1)
                    .addGap(28, 28, 28)
                    .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                        .addComponent(jLabel2)
                        .addComponent(jLabel3))
                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                    .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                        .addComponent(firstCountry, javax.swing.GroupLayout.DEFAULT_SIZE, 42, Short.MAX_VALUE)
                        .addComponent(secondCountry))
                    .addGap(18, 18, 18)
                    .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                        .addComponent(t1, javax.swing.GroupLayout.DEFAULT_SIZE, 42, Short.MAX_VALUE)
                        .addComponent(t2))
                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                    .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                        .addGroup(jPanel1Layout.createSequentialGroup()
                            .addComponent(secondCurrencyUnit, javax.swing.GroupLayout.PREFERRED_SIZE, 20, javax.swing.GroupLayout.PREFERRED_SIZE)
                            .addGap(23, 23, 23))
                        .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
                            .addComponent(firstCurrencyUnit, javax.swing.GroupLayout.PREFERRED_SIZE, 20, javax.swing.GroupLayout.PREFERRED_SIZE)
                            .addGap(18, 18, 18)))
                    .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                        .addComponent(jButton1)
                        .addComponent(jButton2)
                        .addComponent(jButton3))
                    .addContainerGap(57, Short.MAX_VALUE))
            );
    
            javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
            getContentPane().setLayout(layout);
            layout.setHorizontalGroup(
                layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGroup(layout.createSequentialGroup()
                    .addContainerGap()
                    .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                    .addContainerGap())
            );
            layout.setVerticalGroup(
                layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGroup(layout.createSequentialGroup()
                    .addContainerGap()
                    .addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
            );
    
            pack();
        }
        private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) {
            System.exit(0);
        }
        private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {   
            firstCountry.setSelectedIndex(0);
            secondCountry.setSelectedIndex(0);
            t1.setText("");
            t2.setText("");
        }
        private void jButton1ActionPerformed(java.awt.event.ActionEvent evt)
        { 
            if(firstCountry.getSelectedItem().equals("Choose One...") || secondCountry.getSelectedItem().equals("Choose One...") || t1.getText().isEmpty()){
                JOptionPane.showMessageDialog(null,"Please fill all the fields");
                return;
            }
            double amountToChange=Double.parseDouble(t1.getText());
            double amountChanged=0.0;
            double amountInPounds=0.0;
            
          switch(firstCountry.getSelectedItem().toString())
            {
            //changing amount into pounds as a standard
            case "USA": amountInPounds = amountToChange/US_Dollar;break;
            case "India":amountInPounds = amountToChange/Indian_Rupee;break;
            case "Brazil":amountInPounds = amountToChange/Brazilian_Real;break;
            case "Canada":amountInPounds = amountToChange/Canadian_Dollar;break;
            case "Kenyan":amountInPounds = amountToChange/Kenyan_Shilling;break;
            case "Indonesia":amountInPounds = amountToChange/Indonesian_Rupiah;break;
            case "Nigeria":amountInPounds = amountToChange/Nigerian_Naira;break;
            case "Philippine":amountInPounds = amountToChange/Philippine_Peso;break;
            case "Pakistan":amountInPounds = amountToChange/Pakistani_Rupee;break;
            default:amountInPounds = 0.0;
            }
            //converting
            switch(secondCountry.getSelectedItem().toString())
            {
            case "USA":amountChanged = amountInPounds * US_Dollar;break;
            case "India":amountChanged = amountInPounds * Indian_Rupee;break;
            case "Brazil":amountChanged = amountInPounds * Brazilian_Real;break;
            case "Canada":amountChanged = amountInPounds * Canadian_Dollar;break;
            case "Kenyan":amountChanged = amountInPounds * Kenyan_Shilling;break;
            case "Indonesia":amountChanged = amountInPounds * Indonesian_Rupiah;break;
            case "Nigeria":amountChanged = amountInPounds * Nigerian_Naira;break;
            case "Philippine":amountChanged = amountInPounds * Philippine_Peso;break;
            case "Pakistan":amountChanged = amountInPounds * Pakistani_Rupee;break;
            default:amountChanged = amountInPounds * 0.0;
            }
            
            String value = String.format("%.3f",amountChanged);
            t2.setText(value);
        }
        private void firstCountryItemStateChanged(java.awt.event.ItemEvent evt) {
            firstCurrencyUnit.setText(currencyUnits[firstCountry.getSelectedIndex()]);
        }
    
        private void secondCountryItemStateChanged(java.awt.event.ItemEvent evt) {
            secondCurrencyUnit.setText(currencyUnits[secondCountry.getSelectedIndex()]);
        }
        public static void main(String args[]) {
            // form
            java.awt.EventQueue.invokeLater(new Runnable() {
                public void run() {
                    new CurrencyConverter().setVisible(true);
                }
            });
        }
    
        // declaring variables
        private javax.swing.JComboBox<String> firstCountry;
        private javax.swing.JLabel firstCurrencyUnit;
        private javax.swing.JButton jButton1;
        private javax.swing.JButton jButton2;
        private javax.swing.JButton jButton3;
        private javax.swing.JLabel jLabel1;
        private javax.swing.JLabel jLabel2;
        private javax.swing.JLabel jLabel3;
        private javax.swing.JPanel jPanel1;
        private javax.swing.JComboBox<String> secondCountry;
        private javax.swing.JLabel secondCurrencyUnit;
        private javax.swing.JTextField t1;
        private javax.swing.JTextField t2;
    }