Question

I made a simple application to open only XML files using JFileChooser. How can I show the open dialog again and again until I open correct XML file or press cancel button?

Answer 1

You could add a file filter to the file chooser that checks whether the file is an xml file.

When the user has selected a file you check that file’s content and if it isn’t valid you just open the filechooser again, e.g. in a loop that exits when either the file is valid or the user selected the cancel option.

Basically the loop might look like this (that’s quickly written and might contain errors):

int option = CANCEL_OPTION;
boolean fileIsValid = false;
do {
 option = filechooser.showOpenDialog(); //or save?
 if( option == OK_OPTION ) {
    fileIsValid = isValid( filechooser.getSelectedFile()); //implementation of isValid() is left for you
 }
} while( option == OK_OPTION && !fileIsValid);

This loop does the following:

• it opens the filechooser and gets the selected option
• when the OK option is selected the selected file is checked
• when the OK option was selected but the selected file is invalid, do another iteration – otherwise end the loop (if another option, e.g. CANCEL, was selected or the file is valid)