Вывод в TextField

public class Application{
  //...//
  public String textFieldStr() {
    return "textFieldStr";
  }
 //...//
}

public class Interface{
 
  Application application;
 
  public Interface() {
    application = new Application();    
    getContentPain().add(createTextField);
    //...//
  }
 
  private JTextField createTextField(){
    JTextField textField = new JTextField();
    textField.setText(application.textFieldStr);
    //...//
    return textField;
  }
}

 
 
 
package application;
 
import javax.swing.JFrame;
import javax.swing.JTextField;
 
public class MyFrame extends JFrame{
 Application application;
    public MyFrame() {
       
        setSize(500,500);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        application = new Application();    
    getContentPain().add(createTextField);
    }
 
    private JTextField createTextField(){
    JTextField textField = new JTextField();
    textField.setText(application.textFieldStr);
    //...//
    return textField;
  }
 
    private Object getContentPain() {
        throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }
}

/*
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 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
 
package application;
 
import javax.swing.JFrame;
 
 
public class Application {
    String textFieldStr;
  public String textFieldStr() {
    return "textFieldStr";
  }
    public static void main(String[] args) {
     MyFrame MyFrame;
       MyFrame = new MyFrame();
        JFrame frame = new MyFrame();
        frame.setVisible(true);
    }
    
}

JFrame frame = new MyFrame();

new MyFrame().setVisible(true);

String textFieldStr