for loop (i) variable used outside the loop or possible solution?

Question

I am trying to find a way for my startTextFieldListener to gain access to some variables in my for loop. Is there a way to do this? I'm sorry if there is an easy solution to this but I am not quite sure how to work around this. I have seen some examples but I did not know how to apply it to my program. Any help would be greatly appreciated.

public class TextArea1{

JTextArea text;
JFrame frame;
JTextField textField;
public int k;
public ArrayList aList;
public String correctAnswer;

public static void main (String [] args) {
    TextArea1 gui = new TextArea1();

    gui.go();
}
private String textLine;

public void go() {
    frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JPanel panel = new JPanel();
    textField = new JTextField("");
    textField.addActionListener(new startTextFieldListener(aList));
    JButton startButton  = new JButton ("Start!");
    startButton.addActionListener(new startButtonListener(aList));


    text = new JTextArea (30, 60);
    text.setLineWrap(true);

    JScrollPane scroller = new JScrollPane(text);
    scroller.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
    scroller.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);

    panel.add(scroller);

    frame.getContentPane().add(BorderLayout.CENTER, panel);
    frame.getContentPane().add(BorderLayout.WEST, startButton);
    frame.getContentPane().add(BorderLayout.SOUTH, textField);      
    frame.setSize(350, 300);
    frame.setVisible(true);
}       



class startButtonListener implements ActionListener {
 ArrayList aList;
 startButtonListener(ArrayList passedInList)
 {
      aList = passedInList;
 }

 @Override
public void actionPerformed(ActionEvent event) {
     String fileName = "test.txt";
    String line;
    ArrayList aList = new ArrayList();

    try {
         try (BufferedReader input = new BufferedReader (new FileReader(fileName))) {
             if (!input.ready())   {
                 throw new IOException();

             }

             while ((line = input.readLine()) !=null) {
                 aList.add(line);
             }}
    } catch (IOException e) {
        System.out.println(e);

    }

    int sz = aList.size();

       for (int k = 0; k< sz; k++) {          

        String correctAnswer = aList.get(k).toString();

    text.append(aList.get(k).toString());
    text.append("\n");
       }   
}
}       
    class startTextFieldListener implements ActionListener {
         startTextFieldListener(ArrayList passedInList)
         {
             aList = passedInList;
         }




         @Override
        public void actionPerformed(ActionEvent event) {
            text.getText();
             if (text.getText().equals(correctAnswer)) {
                JOptionPane.showMessageDialog(null, "Hooray!");
             }

             else if (!text.getText().equals(correctAnswer)) {
                JOptionPane.showMessageDialog(null, "Wrong!");


             }

            }



             }
        }

dont get your point doing that.. what result do you expected? — David
– David, Commented Apr 25, 2014 at 3:22
When you use i in your listener, what value are you expecting it to be? — takendarkk
– takendarkk, Commented Apr 25, 2014 at 3:23
Looking at this again, it would not even work right? I wanted to check if the textField is the same as the correctAnswer string. I'm not sure how to have this work in two different listeners but is there a way to have both a text field and a textarea together? — user3100858
– user3100858, Commented Apr 25, 2014 at 3:31

Jake Chasan · Accepted Answer · 2014-04-25 04:50:21Z

3

You could attempt to do this by trying to make the variables accessible to the entire class.

To implement this, you can add the variable declaration where you have declared your User Interface items, after the class declaration.

You could then access this variable in another class.

Example Code:

public class TextArea1{

JTextArea text;
JFrame frame;
JTextField textField;

public int sampleIntToBeUsed;

You could also implement this with various get/set methods.

How to Make a Constructor: (Put the name of the class with no return type)

class startButtonListener implements ActionListener {
     ArrayList aList;
     startButtonListener(ArrayList passedInList)
     {
          aList = passedInList;
     }

New Second ActionListener

class startTextFieldListener implements ActionListener {
     String correctAnswer;
     startTextFieldListener(String answer)
     {
         correctAnswer = answer;
     }

         @Override
        public void actionPerformed(ActionEvent event) {
             if (text.getText().equals(correctAnswer)) {
                JOptionPane.showMessageDialog(null, "Hooray!");
             }

             else {
                JOptionPane.showMessageDialog(null, "Wrong!");
             }

          }
     }
    }

edited Apr 25, 2014 at 4:50

answered Apr 25, 2014 at 3:23

Jake Chasan

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20 Comments

Baby Over a year ago

I believe OP is referring to i variable, which belongs to the for loop

Jake Chasan Over a year ago

Yes, but instead of using i, the loop can use sampleIntToBeUsed.

user3100858 Over a year ago

Thank you for the help. I've changed (i) but now the aList variable comes underlined. Would you know how to fix that? I have tried making the array public too but it did not allow me to use toString() due to "not allowed to use void).

Jake Chasan Over a year ago

Can you revise the code in the question? (If you post the updated code I may be able to help)

Jake Chasan Over a year ago

Ok, in the listener classes, I would add a constructor that takes the aList as a parameter. Then set ArrayList aList = passedInList; in the listener classes. Does this help?

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