How to move between frames/classes after clicking a button in java gui?

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Java

GUI

import java.awt.EventQueue;

import javax.swing.JFrame;
import javax.swing.JLabel;
import java.awt.Font;
import java.awt.Window.Type;
import java.awt.Color;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;

public class WelcomePage extends AdminLogin {

	private JFrame frame;
	private JButton btnAdmin;

	/**
	 * Launch the application.
	 */
	public static void main(String[] args) {
		EventQueue.invokeLater(new Runnable() {
			public void run() {
				try {
					WelcomePage window = new WelcomePage();
					window.frame.setVisible(true);
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		});
	}

	/**
	 * Create the application.
	 */
	public WelcomePage() {
		initialize();
	}

	/**
	 * Initialize the contents of the frame.
	 */
	private void initialize() {
		frame = new JFrame();
		frame.getContentPane().setBackground(Color.BLUE);
		frame.setBackground(Color.BLUE);
		frame.setBounds(100, 100, 495, 300);
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.getContentPane().setLayout(null);

		JLabel lblOnlineElectionManager = new JLabel(
				"Welcome To Online Election Manager");
		lblOnlineElectionManager.setForeground(Color.WHITE);
		lblOnlineElectionManager.setFont(new Font("Tahoma", Font.PLAIN, 16));
		lblOnlineElectionManager.setBounds(100, 11, 284, 47);
		frame.getContentPane().add(lblOnlineElectionManager);

		JLabel lblLoginAs = new JLabel("Login as");
		lblLoginAs.setForeground(Color.WHITE);
		lblLoginAs.setFont(new Font("Tahoma", Font.PLAIN, 16));
		lblLoginAs.setBounds(195, 84, 77, 36);
		frame.getContentPane().add(lblLoginAs);

		btnAdmin = new JButton("ADMIN");
		btnAdmin.setFont(new Font("Tahoma", Font.PLAIN, 16));
		btnAdmin.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {

				if (e.getSource() == btnAdmin) {
					AdminLogin admin = new AdminLogin();
					frame.setVisible(false);
					admin.setVisible(true);
				}

			}
		});
		btnAdmin.setBounds(45, 192, 117, 36);
		frame.getContentPane().add(btnAdmin);

		JButton btnVoter = new JButton("VOTER");
		btnVoter.setFont(new Font("Tahoma", Font.PLAIN, 16));
		btnVoter.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent arg0) {
			}
		});
		btnVoter.setBounds(267, 192, 117, 36);
		frame.getContentPane().add(btnVoter);
	}

}

What I have tried:

I tried creating an instance of the second class "AdminLogin" which i want to move to after clicking a button on this "WelcomePage" class. When i try to run there's an error at "admin.setVisible(true)". What did i do wring?