how to populate text field with a selection from a JComboBox in java GUI
<p>I am new to java GUI I'm having trouble filling text field
using a JComboBox data from a text file 
text files has multiple rooms with the following format </p>

<p>accountNumber &lt;> customerName &lt;> balance</p>

<p>when an account number is selected from the combo for the 
right name and balance need to populate on the text field
so far I have a class called AccountUtility which reads the data
from the text file I am using an ArrayList to populate the combo box 
and a hashmap to map all names and balances
so far I am only able to populate the combo box 
I'm having problems filling in the text file 
any help and suggestions are really appreciated </p>

<pre><code> //class that reads text file//////
 public class AccountUtility {
    ArrayList&lt;String&gt; test = new ArrayList&lt;String&gt;();
    HashMap&lt;String, String&gt; map = new HashMap&lt;String, String&gt;();
    String[] number;
    String columns[], accountNumber, customerName,balance;
    int size;


public AccountUtility(){


    BufferedReader in = null;
    try{    // assume products.txt already exists
    in = new BufferedReader(new FileReader("accounts.txt"));
    String line = in.readLine();
    while(line != null)  {
    columns = line.split("&lt;&gt;");
    accountNumber = columns[0];
    customerName = columns[1];
    balance = columns[2];

    test.add(accountNumber);
    map.put(customerName, balance);


                    line = in.readLine();
            }
            in.close();
    }
    catch(IOException ioe)
    {
            System.out.println(ioe);
    }
} 
 public ArrayList&lt;String&gt; getAccountNumbers( ){
     return test;
}
public HashMap&lt;String, String&gt; getMap(){
    return map;
}




//method on main class that populates JComboBox
    public AccountApp() {

        initComponents();
        setLocationRelativeTo(null);

        // Populate JComboBox
        AccountUtility gc = new AccountUtility();
        for( String one : gc.getAccountNumbers()){ 
        accountNumberComboBox.addItem(one);
        }
    }
</code></pre>

<p>This is what the GUI looks so far</p>

<p><a href="https://i.stack.imgur.com/hjgEj.png" rel="nofollow noreferrer">enter image description here</a></p>