BufferedWriter(Writer out) and flush()

Question

BufferedWriter(Writer out)
correct me if i'm wrong, but when i use BufferedWriter(Writer out) as in
pout = new PrintWriter(new BufferedWriter(new FileWriter("log.txt");
i do not have to call flush().
it will automatically call flush when the buffer is 512 is that correct ?
or do i have to still call flush to make sure the contents come out.
Stephen

Answer 1

I'm using jav 1.4.
Notice the code below:
I get a null exception when trying to write() a second time with the PrintWriter instance .
Here is the error
Tracer constructor works
getLogFileDate() = Jun-14--2002-8.17.42-AM
getLogFileDate() = Jun-14--2002-8.17.42-AM
main method starts
main method successfully gets Tracer instance tt. com.myinteractivesite.Tracer@888759
Exception in thread "main" java.lang.NullPointerException
at com.myinteractivesite.Tracer.log(Tracer.java:29)
at com.myinteractivesite.Tracer.main(Tracer.java:72)
Why do I get this null exception when trying to write a second time using the printwriter in the log() method ?
* Tracer.class logs items according to the following criteria:
* @since June 2002
import java.io.*;
import java.net.*;
import java.util.*;
import java.text.*;
class Tracer{
     public static void log(int traceLevel, String message, Object value)
          pout.write(getLogFileDate(new Date()) +" >" + message + " value = " + value.toString());
     public static void log(int traceLevel, String message )
          pout.write("HI HOW ARE YOU " ) ;
          pout.flush();
     //public static accessor method
     public static Tracer getTracerInstance()
          return tracerInstance;
     private static String getLogFileDate(Date d )
          String s = df.format(d);
          String s1= s.replace(',','-');
          String s2= s1.replace(' ','-');
          String s3= s2.replace(':','.');
          System.out.println("getLogFileDate() = " + s3 ) ;
          return s3;
     //private instance
     private Tracer(){
          System.out.println("Tracer constructor works");
          df = DateFormat.getDateTimeInstance(DateFormat.MEDIUM, DateFormat.MEDIUM);
          date                    = new java.util.Date();
          try{
          pout = new PrintWriter(new BufferedWriter(new FileWriter("Crawler_log"+getLogFileDate(new Date())+".txt", true)));
          pout.write("**************** New Log File Created "+ getLogFileDate(new Date()) +"****************");
          pout.flush();
          }catch (IOException e){
          System.out.println("**********THERE WAS A CRITICAL ERROR GETTING TRACER SINGLETON INITIALIZED. APPLICATION WILL STOP EXECUTION. ******* ");
     public static void main(String[] argz){
     System.out.println("main method starts ");
     Tracer tt = Tracer.getTracerInstance();
     System.out.println("main method successfully gets Tracer instance tt. "+ tt.toString());
     //the next method is where it fails - on pout.write() of log method. Why ?
     tt.log(1, "HIGH PRIORITY");
     System.out.println("main method ends ");
     //private static reference
     private static Tracer tracerInstance = new Tracer();
     private static Date date     = null;
     private static PrintWriter pout = null;
     public static DateFormat df = null;
}