How do I use a Main class to implement Swing Components from other classes in my project?

Question

Im developing a project in which I have "Class1", "Class2", and "Class3". Class2 and Class3 both create JFrame's, each containing various JButton's, JLabel's, and other swing components. How do i make so in Class1 I can reffrence the JButton from Class2 and use an action listener to set the Class2's visibilty to false and Class3's visibilty to true.

I Tried This: Setting Class2 to visbile in my main method was no issue, but once i started to implement Class3 things didint work.

Summary: Having Issues initiating a jbutton from an other class and using an action listener that refrences that jbutton.

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;

@SuppressWarnings("serial")
public class Class1 extends JFrame implements ActionListener
{

    public static void main(String[] args) {
        Class2 frameFromclass2 = new Class2();

        frameFromclass2.setVisible(true);
    }       
    Class2 buttonMovetoclass3 = new Class2();

    public void actionPerformed(ActionEvent e) {

        if (buttonMovetoclass3 == e.getSource()) {   
            Class2 frameFromclass2 = new Class2();

            frameFromclass2.setVisible(false);

            Class3 frameFromclass3 = new Class3();

            frameFromclass3.setVisible(true);

                        
        }
    }   
    
}

Answer 1

Part of your problem is caused by a lack of understanding in terms of variable scope. The other part of your problem is just in approaching this the wrong way.

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;

@SuppressWarnings("serial")
public class Class1 extends JFrame implements ActionListener
{
    //This is a method. Every variable declared within this method, 
    //is only accessible from within this method. 
    public static void main(String[] args) {
        //That includes this one. 
        Class2 frameFromclass2 = new Class2();
        //You've used it here, but not only is it then abandoned, but it
        //cannot be used anywhere else. It is contained in a cage of curly braces. 
        frameFromclass2.setVisible(true);
    }       
    Class2 buttonMovetoclass3 = new Class2();

    public void actionPerformed(ActionEvent e) {

        if (buttonMovetoclass3 == e.getSource()) {   
            //Here you create a NEW Class2 object and give it the same
            //name you gave the other, then you hide it.
            Class2 frameFromclass2 = new Class2();

            frameFromclass2.setVisible(false);
            //And then you do the same thing here, but with Class3; then you show it. 
            Class3 frameFromclass3 = new Class3();

            frameFromclass3.setVisible(true);
        }
    }   
}

We aren't able to see what your other classes have in their constructors, so I can't say whether or not there's also a problem happening there. I can, however, offer better alternatives.

Generally you want to keep 1 JFrame, even if you have popup windows or multiple "pages" that can be used. Consider using multiple JPanels, one per layout. Alternatively you can use a JTabbedPane, and have different information on each tab. For login purposes, a common option is the JOptionPane or a JDialog. If you insist on using multiple JFrames and you want to move components between them, variables within your class (not a method) should be used to store information, then use public methods to access those variables from the other classes. Once a window is done being used, however, you should destroy it instead of hide it. Here's a great resource on various ways to do that.