如何在Java中访问循环外的变量？

Question

所以我有我的if语句在.txt文件中搜索与用户键入的国家/地区对应的货币代码。我将这些国家/地区代码存储在名为'from'和'to'的字符串中。我需要访问存储在'from'和'to'变量中的if语句的结果，以便稍后插入。当我尝试在最后一行中使用这些时，它说无法找到符号'from'并且找不到符号'to'。我怎样才能解决这个问题？

//all my imports here

public class ExchangeApp {
    public static void main(String[] args) {
        JFrame frame = new JFrame();
        frame.setSize(300,400);
        frame.setTitle("Exchange App");
        JPanel panel = new JPanel();
        panel.setLayout(new GridLayout(8, 2, 5, 3));
        //GUI Elements
        JLabel toLabel = new JLabel("To");
        JTextField CurrencyTo = new JTextField(20);
        JLabel fromLabel = new JLabel("From");
        JTextField CurrencyFrom = new JTextField(20);
        JLabel amountLabel = new JLabel("Amount");
        JTextField AmountText = new JTextField(20);
        JLabel displayLabel = new JLabel();
        JLabel updateLabel = new JLabel();
        JButton Calculate = new JButton("Calculate");
        JButton Clear = new JButton("Clear");
        //Add elements to panel
        panel.setComponentOrientation(ComponentOrientation.LEFT_TO_RIGHT);
        panel.add(fromLabel);
        panel.add(CurrencyFrom);
        panel.add(toLabel);
        panel.add(CurrencyTo);
        panel.add(amountLabel);
        panel.add(AmountText);
        panel.add(Calculate);
        panel.add(Clear);
        panel.add(displayLabel);
        panel.add(updateLabel);
        //make visible
        frame.add(panel);
        frame.setVisible(true);

    class calculateListener implements ActionListener{
        @Override
        public void actionPerformed(ActionEvent event){
            if(event.getSource()==Calculate){
                String line, from, to;
                String fromString = CurrencyFrom.getText();
                String toString = CurrencyTo.getText();
                double amount = Double.parseDouble(AmountText.getText());
                try{
                      //import text file
                      File inputFile = new File("currency.txt");
                      //create file scanner
                      Scanner input = new Scanner(inputFile);
                    try{
                      //skip first line
                      input.nextLine();
                      //while has next line
                      while(input.hasNextLine()){
                          //set line equal to entire line
                          line = input.nextLine();
                          String[] countryArray = line.split("\t");
                          //search for from
                          if(fromString.equals(countryArray[0])){
                              //set 'from' equal to that country code
                              from = countryArray[2];
                              //testing
                              System.out.println(from);
                          }
                          //search for to
                          if(toString.equals(countryArray[0])){
                              //set 'to' equal to that country code
                              to = countryArray[2];
                              System.out.println(to);
                          }
                          else{
                              displayLabel.setText("To country not found");
                          }
                      }//while loop
                  }//2nd try
                    finally{input.close();}
                }//1st try
                  catch(IOException exception){
                      System.out.println(exception);
                  }//catch bracket
        }//if bracket                                                              ****these 2 variables****
            String address = "http://finance.yahoo.com/d/quotes.csv?e=.csv&f=sl1d1t1&s=" + from + to;
    }//action bracket 
}//class implements action listener bracket
    ActionListener listener = new calculateListener();
    Calculate.addActionListener(listener);
}//main bracket
}//class bracket