NEED HELP WITH THE CODE IOException

void writer() {

        FileWriter file= new FileWriter("tester.txt");
        BufferedWriter bw=new BufferedWriter(file);
        PrintWriter out = new PrintWriter(bw);

        for(int i=0;i<_currentRack.getNoOfCds();i++){

            Vector tempV=_currentRack.getCdVector();
            Cd _cd=((Cd)tempV.get(i));

            out.println(_cd.getType());
            out.println(_cd.getTitle());
            out.println(_cd.getNoOfCopies());
            out.println("*");
        }

        out.close();
        bw.close();
        file.close();

    }

    public void actionPerformed(ActionEvent e) {
        System.out.println(e);
       // JOptionPane.showMessageDialog(rootPane, e.getActionCommand
());
       viewCdInfo(_currentRack.findCd(e.getActionCommand()));
    if(e.getActionCommand().equals("Exit")){

        writer();

        System.exit(0);

        }

    if (e.getActionCommand().equals("See All Cds Info")){
        System.out.println(e);
        printCdInfo(_currentRack.printCds());
    }

    if (e.getActionCommand().equals("Add a New CD")){
        System.out.println(e);
        addCd();
    }

    if (e.getActionCommand().equals("Remove CD(s)")){
        System.out.println(e);
        removeCd();
    }

    }
}

where do i write the throws exception command??