StringBuilder em Web

StringBuilder sb = new StringBuilder();
sb.append("Construindo uma");
sb.append("String com a utilização");
sb.append("do StringBuilder.");


System.out.println(sb.toString());

public void lerArray(ArrayList arrL, ArrayList urlArray) {
        try {
            StringBuilder strBuilder = new StringBuilder();
            //StringBuffer strBuffer = new StringBuffer();
            //Iterator it = arrL.iterator();
            //int i = 0;
            for (int i = 0; i < arrL.size(); i++){
                //while(it.hasNext()){
                System.out.println("posicao = "+i+" valor = "+arrL.get(i));
                if ((i % 3) == 0){
strBuilder.append("parte_1"+arrL.get(0)+",+"+arrL.get(1)+"+-+"+arrL.get(2)+"cod_0"+arrL.get(i)+",+"+arrL.get(1)+"+-+"+arrL.get(2)+"cod_1").insert(57,"-").insert(91,"-");
                    urlArray.add(strBuilder.toString());
                }
            }
            gravaURL(String.valueOf(urlArray));
            extrairValor(urlArray);
        } catch (Exception e){
            System.out.println(e);
        }
    }

private void gravaURL(String strURL) {
        try {
            File saida = new File("str_url.txt");
            BufferedWriter bw = new BufferedWriter(new FileWriter(saida, true));
            bw.write(strURL);
            bw.write("\n");
            bw.close();
        } catch (IOException ioe) {
            ioe.printStackTrace();
        }
    }