IO流(异常的日志信息)

import java.io.*;import java.util.*;import java.text.*;class ExceptionInfo{    public static void main(String[] args) throws IOException    {        try        {            int[] arr = new int[2];            System.out.println(arr[3]);        }        catch(Exception e)        {            try            {                Date d = new Date();                SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");                String s = sdf.format(d);                                 PrintStream ps = new PrintStream("a-exeception.log");                ps.println(s);                System.setOut(ps);                             }            catch(IOException ex)            {                throw new RuntimeException("日志文件创建失败");            }            e.printStackTrace(System.out);        }    }} //log4j