code: private void btSearchInputDirActionPerformed(java.awt.event.ActionEvent evt)//GEN-FIRST:event_btSearchInputDirActionPerformed
      {//GEN-HEADEREND:event_btSearchInputDirActionPerformed
  
        if (!"".equals(txtInputDir.getText()))
        {
          File f = new File(txtInputDir.getText());
          if (f.exists() && (f.isDirectory() || "zip".equals(Files.getFileExtension(f.getName()))))
          {
            fileChooser.setSelectedFile(f);
          }
        }
  
        if (fileChooser.showDialog(this, "Select") == JFileChooser.APPROVE_OPTION)
        {
          File f = fileChooser.getSelectedFile();
          txtInputDir.setText(f.getAbsolutePath());
          storeProperties();
        }
  
      }
docs: GEN-LAST:event_btOkActionPerformed