Setting a JLabel visible on JRadioButton click

Question

I tried setting JLabel to being visible only after I select a certain JRadioButton. The program is getting an error if I set lblNewLabel_1.setVisible(true) in the action performed of a radio button. It worked with the text field, but with this not. What can I do? Is it different with the label? Is there any advice someone can offer me?

import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.Window;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JTextArea;
import javax.swing.JRadioButton;
import javax.swing.JLabel;

import java.awt.Font;

import javax.swing.JTextField;
import javax.swing.ButtonGroup;

import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;


public class Fereastra extends JFrame {

    private JPanel contentPane;
    private JTextField textField;
    private JTextField textField_1;
    private final ButtonGroup buttonGroup = new ButtonGroup();

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

    /**
     * Create the frame.
     */
    public Fereastra() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 751, 565);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        contentPane.setLayout(null);
        setContentPane(contentPane);
        
        JTextArea textArea = new JTextArea();
        textArea.setBounds(12, 13, 447, 251);
        contentPane.add(textArea);
        
        JRadioButton rdbtnNewRadioButton = new JRadioButton("Cautarea pe nivel");
        rdbtnNewRadioButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                if(rdbtnNewRadioButton.isSelected())
                {
                    textField.setVisible(false);
                    textField_1.setVisible(false);
    


                }
                
            }
        });
        buttonGroup.add(rdbtnNewRadioButton);
        rdbtnNewRadioButton.setBounds(488, 55, 185, 25);
        contentPane.add(rdbtnNewRadioButton);       
        
        JRadioButton rdbtnNewRadioButton_1 = new JRadioButton("Cautarea in adancime");
        rdbtnNewRadioButton_1.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                if(rdbtnNewRadioButton_1.isSelected())
                {
                    textField.setVisible(true);
                    textField_1.setVisible(true);

                }
                else
                {
                    textField.setVisible(false);
                    textField_1.setVisible(false);
            


                }
                
            }
        });
        buttonGroup.add(rdbtnNewRadioButton_1);
        rdbtnNewRadioButton_1.setBounds(488, 96, 237, 25);
        contentPane.add(rdbtnNewRadioButton_1);
                    
        JRadioButton rdbtnNewRadioButton_2 = new JRadioButton("Costul uniform");
        rdbtnNewRadioButton_2.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                if(rdbtnNewRadioButton_2.isSelected())
                {
                    textField.setVisible(false);
                    textField_1.setVisible(false);

                }
            }
        });
        buttonGroup.add(rdbtnNewRadioButton_2);
        rdbtnNewRadioButton_2.setBounds(488, 138, 127, 25);
        contentPane.add(rdbtnNewRadioButton_2);
        
        JRadioButton rdbtnNewRadioButton_3 = new JRadioButton("Adancime iterativa");
        rdbtnNewRadioButton_3.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                if(rdbtnNewRadioButton_3.isSelected())
                {
                    textField_1.setVisible(true);
                    textField.setVisible(true);
                }
                else
                {
                    textField_1.setVisible(false);
                    textField.setVisible(false);


                }
            }
        });
        buttonGroup.add(rdbtnNewRadioButton_3);
        rdbtnNewRadioButton_3.setBounds(488, 179, 237, 25);
        contentPane.add(rdbtnNewRadioButton_3);
        
        JRadioButton rdbtnNewRadioButton_4 = new JRadioButton("Greedy");
        rdbtnNewRadioButton_4.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                if(rdbtnNewRadioButton_4.isSelected())
                {
                    textField.setVisible(false);
                    textField_1.setVisible(false);


                }
            }
        });
        buttonGroup.add(rdbtnNewRadioButton_4);
        rdbtnNewRadioButton_4.setBounds(488, 221, 127, 25);
        contentPane.add(rdbtnNewRadioButton_4);
        
        JLabel lblNewLabel = new JLabel("Alegeti:");
        lblNewLabel.setFont(new Font("Tahoma", Font.PLAIN, 16));
        lblNewLabel.setBounds(488, 13, 84, 33);
        contentPane.add(lblNewLabel);
        
        textField = new JTextField();
        textField.setBounds(402, 277, 116, 22);
        contentPane.add(textField);
        textField.setColumns(10);
        textField.setVisible(false);
        
        textField_1 = new JTextField();
        textField_1.setBounds(246, 277, 116, 22);
        contentPane.add(textField_1);
        textField_1.setColumns(10);
        textField_1.setVisible(false);

        
        JLabel lblNewLabel_1 = new JLabel("Introduceti valorile dorite:");
        lblNewLabel_1.setFont(new Font("Tahoma", Font.PLAIN, 16));
        lblNewLabel_1.setBounds(22, 277, 212, 21);
        contentPane.add(lblNewLabel_1);
        lblNewLabel_1.setVisible(false);
        
    }
}

Answer 1

It's because your label is declared in function context, put the declaration next the textbox declaration and it should work fine