Question

I am creating a java desktop application. In the application I generate report using dynamic report and based on some parameter the report will generate. The user generates the first report and it is then displayed in a jasper viewer. The user minimizes the jasper viewer and generates next report. It is then viewed in a new jasper viewer.

So each time the user generates a report a new jasper viewer is created. How do I reuse or ensure only one JasperViewer exists at a time?

JasperPrint print=report.toJasperPrint();
JasperViewer.viewReport(print, false);

After that I created object for jasperviewer.

JasperViewer jv;
 JasperPrint print;
public void action()
{
  button.addActionListener(new ActionListener()
                {
                       @Override
                       public void actionPerformed(ActionEvent e) {
                          try
                          {
                             report.addColumn(...);
                               ...
                               ...
                              print=report.toJasperPrint();
                           jv=new JasperViewer(print,false);
                           jv.setVisible(true);
                          }
                        });
                 }
   }

Answer 1

Just to start off, you sample code does not compile. Once formatted correctly, you see that the closing parenthesis and semicolon happen to soon. It should look like:

JasperViewer jv;
JasperPrint print;
public void action() {
  button.addActionListener(new ActionListener() {
    @Override
    public void actionPerformed(ActionEvent e) {
      try {
        report.addColumn(...);
        ...
        ...
        print=report.toJasperPrint();
        jv=new JasperViewer(print,false);
        jv.setVisible(true);
      }
    }
  });
}

Now to the question. JasperViewer extends JFrame and as such any tricks to close it programatically should also work for JasperViewer. Since you are storing a reference to the JasperViewer, you could check if it is already initialized. If it is send a window event to it to close it.

if (jv != null && jv.isVisible()) {
    WindowEvent wev = new WindowEvent(jv, WindowEvent.WINDOW_CLOSING);
    Toolkit.getDefaultToolkit().getSystemEventQueue().postEvent(wev);
}