Accessing JTextArea from another class

[jimutt]

Hi, I've been programming for quite a long time in PHP and other web programming languages but I'm really new to Java. And as I've been using a procedural approach when programming in PHP I'm quite new to OOP as well. Now I'm following a very basic Java tutorial.

I have this code for displaying to different "bank accounts":

public class UseAccount extends JFrame {

public static void main(String[] args) {
    
    Account myAccount = new Account();
    Account yourAccount = new Account();
    
    myAccount.name = "Jimmy";  
    myAccount.address = "Arjeplogsvägen 1";
    myAccount.balance = 1250.70;
    
    yourAccount.name = "Greg Giraldo";
    yourAccount.address = "Fishermans friend's 4";
    yourAccount.balance = -5820.30;
    
    myAccount.display();
    System.out.println();
    yourAccount.display();
}
}

And here is the "Account" class:

public class Account{
    String name;
    String address;
    double balance;
    
    void display() {
        System.out.print(name);
        System.out.print(" (");
        System.out.print(address);
        System.out.print(") has $");
        System.out.print(balance);
    }     
}

This works really well. but now I want to output this information to a JTextArea. So I've written this code for the UseAccount class:

import java.awt.*;
import javax.swing.*;

public class UseAccount extends JFrame {
        JTextArea output = new JTextArea();
    
    public UseAccount() {
        setLayout(new BorderLayout());
        add(output, BorderLayout.CENTER);
    }
    
    public static void main(String[] args) {
    UseAccount frame = new UseAccount();
    frame.setTitle("Account");
    frame.setSize(500,400);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setVisible(true);
    
    Account myAccount = new Account();
    Account yourAccount = new Account();
    
    myAccount.name = "Jimmy";  
    myAccount.address = "Arjeplogsvägen 1";
    myAccount.balance = 1250.70;
    
    yourAccount.name = "Greg Giraldo";
    yourAccount.address = "Fishermans friend's 4";
    yourAccount.balance = -5820.30;
    
    myAccount.display();
    System.out.println();
    yourAccount.display();
    }
}

And then I was trying to make the "Account" class extend the "UseAccount" class and then use output.append("the_text") for displaying the text. But this obviously doesn't work:

public class Account extends UseAccount{
    String name;
    String address;
    double balance;
    
    void display() {
        output.append(name);
        output.append(" (");
        output.append(address);
        System.out.print(") has $");
        System.out.print(balance);
    }     
}

(I did not change every system.out.print() to output.append as it isn't working anyway.

I'm wondering how to access and change the text of my textarea("output") from this other class?

I hope someone will be able to help me with this little problem.

[Fou-Lu]

Don't. Keep them separate, one to present the output, and one to process the data.
There are several routes you can go with though. You can take a Document type, or a StringBuilder and append to that for example, or you can simply return a string. I'd do neither and opt for using single property accessor's instead, but if I were to group them I'd return a string:

PHP Code:

public String display()
{
    StringBuilder sb = new StringBuilder();
    sb.append(name);
    sb.append(" (");
    sb.append(address);
    sb.append(") has $");
    sb.append(balance);
    return sb.toString();
}

// Used
jtText.setText(object.display()); 


Unfortunately I don't believe there is a really generic interface to work with when it comes to the swing JTextArea. Document I think is the lowest you can really go, and its still a javax.swing.text type. There's some patterned approaches you can follow as well, but those are more advanced and require a good understanding of OOP to implement.