JAVA JDialog, 새창 띄우기, 다이얼로그, Swing

import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JLabel;
 
public class NewWinJDilog {
        public static void main (String [] args) {
                test_Frame tf = new test_Frame();
        }
}

class test_Frame2 extends JDialog{
        JLabel jlb = new JLabel("");
        public test_Frame2(String str){
                getContentPane().add(jlb);
               
                jlb.setText(str.toString());
               
                this.setSize(200,100);
                this.setModal(true);
                this.setVisible(true);
               
        }
}