how to prevent running same JInternalFrame more than once

Question

How can you prevent the JInternalFrame not to open more once, currently in my application it opens many times. Also how can I make my application run only if there is not the same application running.

This is the code for JInternalFrame

private void Cash_ButtonActionPerformed(java.awt.event.ActionEvent evt) {                                            

    Provider provider = new Provider();
      MainMenu.add (provider);
       provider.setClosable(true);
    }

Answer 1

Try adding a condition and making provider a local variable

private Provider provider = new Provider();

public Your_Class_Name(){
    provider.setClosable(true);
}

private void Cash_ButtonActionPerformed(java.awt.event.ActionEvent evt) {
    if(provider.isVisible()) return;
    MainMenu.add (provider);
}