private void btnDisplayActionPerformed(java.awt.event.ActionEvent evt) {//GEN-FIRST:event_btnDisplayActionPerformed
        // TODO add your handling code here:
        
        for(int i = 0; i < aList.size(); i++){
            JOptionPane.showMessageDialog(null, "Student ID: "+aList.get(i).getStudent() 
                    +"\n Book Name: "+aList.get(i).getBookName()+"\n Book Category:"+aList.get(i).getBookCategory());
        }
    }//GEN-LAST:event_btnDisplayActionPerformed