java中exception的printStackTrace()输出内容转成字符串

ArrayList list = new ArrayList();
try {
System.out.println(list.get(1));
} catch (Exception e) {
e.printStackTrace();
System.out.println("=========================");
StringWriter sw = new StringWriter();    
PrintWriter pw = new PrintWriter(sw);    
e.printStackTrace(pw);    
String msg=sw.toString();  

System.out.println(msg);
}