Question

for example i create this on click

//this creates autor object with default constructor properties defined in autor class
menuAutor.addMouseListener(new MouseAdapter(){
            public void mouseClicked(MouseEvent e)
            {
                autor Autor = new autor("Autor");
            }
        });

so object named Autor is created, and when i click again on the button, it pops up again the same Autor object.. how can prevent opening the same window if one is already opened?

EDIT: FINALY A SOLUTION!
After lots of thinking about this.. i made my solution…
default value for autorOpen=”no” i declaired at the beginning of my class, just to let you know because its not visible in code below, the solution itself:

public void mouseClicked(MouseEvent e)
            {
                if(autorOpen=="no") {
                autor Autor = new autor("Autor");
                autorOpen = "yes";
                Autor.addWindowListener(new WindowAdapter(){
                    public void windowClosing(WindowEvent e) 
                    {
                        autorOpen = "no";
                    }
                });
                }
                else 
                    JOptionPane.showMessageDialog(null, "Demo notice... you can't open that window again.. its opened already!","Error",JOptionPane.ERROR_MESSAGE);  
            }
        });

Answer 1

Store the variable a little bit more globally, and check whether it exists before creating a new one.