PrintWriter after log()

[Faisal Ahmad]

Could you please look into the below code and tell me why PrintWriter object doesn't work when called after writing to log?

package com.example.servlets;

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import com.example.model.Dog;

public class TestServlet extends HttpServlet{
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException{
		response.setContentType("text/html");
		PrintWriter rWriter = response.getWriter();//Working. Can see the output in browser as well as log file.
		Dog dog = (Dog) this.getServletContext().getAttribute("dog");
		this.getServletContext().log(dog.getBreed());
		//PrintWriter rWriter = response.getWriter();//Can see the output only in log file. Browser shows nothing. Why?
		rWriter.println(dog.getBreed());
	}
}

[Niiraj Patel]

Hi Faisal,

For the output to be made correctly, PrintWriter object should be flushed and must be closed with its flush() and close() methods.

e.g.
rWriter.flush(); // Writes the remaining data to the screen
rWriter.close(); // Finishes the work

Regards,
Niraj

[Faisal Ahmad]

Hi Niraj!

Thanks so much! So, flushing and closing are must? Why it worked when rWriter was used prior to writing to log?

[Niiraj Patel]

flushing and closing are must?

PrintWriter object should be flushed and must be closed.

flush() should not be necessary but it's good to know that the PrintWriter does not flush before it closes the underlying stream.

Why it worked when rWriter was used prior to writing

PrintWriter has no relation with ServletContext.log()

Regards,
Niraj

[Faisal Ahmad]

Thanks a lot! Will remember it always.