java操作将内容写入文件

public static boolean updateFile(String str)
{
   str = "test";
   boolean blg = false;
   try {
    BufferedWriter bw = new BufferedWriter(new FileWriter("C://data.txt"));
    StringBuilder sb = new StringBuilder("");
    sb.append(str);
    String a = sb.toString();
    byte[] b = (a).getBytes();
    // 写入文件，还可以用其他方法如：write(String str)
    bw.write(a, 0, b.length);
    bw.close();
   } catch (IOException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }
   return blg ;
}