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Formatting Output with PrintWriter (Logger1.java) Java code example - Click here to copy ->>>
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// -----------------------------------------------------------------------------
// Logger1.java
// -----------------------------------------------------------------------------
/*
* =============================================================================
* Copyright (c) 1998-2005 Jeffrey M. Hunter. All rights reserved.
*
* All source code and material located at the Internet address of
* http://www.idevelopment.info is the copyright of Jeffrey M. Hunter, 2005 and
* is protected under copyright laws of the United States. This source code may
* not be hosted on any other site without my express, prior, written
* permission. Application to host any of the material elsewhere can be made by
* contacting me at jhunter@idevelopment.info.
*
* I have made every effort and taken great care in making sure that the source
* code and other content included on my web site is technically accurate, but I
* disclaim any and all responsibility for any loss, damage or destruction of
* data or any other property which may arise from relying on it. I will in no
* case be liable for any monetary damages arising from such loss, damage or
* destruction.
*
* As with any code, ensure to test this code in a development environment
* before attempting to run it in production.
* =============================================================================
*/
import java.io.*;
import java.util.*;
/**
* -----------------------------------------------------------------------------
* Used to test the Java I/O package to format output to a file using the
* PrintWriter wrapper class.
* <p>
* FileWriter by itself works, but Java has another class that makes it much
* easier to do simple text output to a file: PrintWriter. PrintWriter has
* print and println methods just like System.out, so using it to write to a
* file is almost the same as just printing text to the screen. Furthermore,
* PrintWriter handles the exceptions for you so you won't need to worry about
* try/catch blocks every time you want to write a line to the file. There is
* still one Exception that has to be dealt with, though. A PrintWriter object
* takes a FileWriter object as a parameter in the constructor. Remember that
* even the constructor of FileWriter throws an exception, so you will have to
* create it inside of a try/catch block.
* <p>
* Think of close() as "Save". Calling close() saves the file. As long as you
* call close() when you are finished writing to the file, you don't need to
* worry about calling flush(). If you forget to call close(), though, nothing
* will be written to the file. It would be the same as if you had typed your
* entire program and then closed Emacs without saving - whoops.
* <p>
* Example usage:
*
* Logger1 log = new Logger1("TestLogger.log");
* log.start();
* log.writeln("main : < Setting counter to 1");
* log.writeln("main : > Out of main with counter at 1024");
* log.stop();
*
* @version 1.0
* @author Jeffrey M. Hunter (jhunter@idevelopment.info)
* @author http://www.idevelopment.info
* -----------------------------------------------------------------------------
*/
public class Logger1 {
private String logFileName = null;
private PrintWriter pw = null;
private Date startTime = null;
private Date stopTime = null;
/**
* Used to write a given String object (without a newline) to the log file.
* @param s String that will be written to the log file.
*/
public void write (String s) {
pw.print(s);
}
/**
* Used to write a given String object (with a newline) to the log file.
* @param s String that will be written to the log file.
*/
public void writeln (String s) {
pw.println(s);
}
/**
* Used to write a newline character to the log file.
*/
public void writeln () {
pw.println();
}
/**
* Used to open the log file for writting. This method MUST be called
* before writting to the log file.
*/
public void start() {
startTime = Calendar.getInstance().getTime();
try {
pw = new PrintWriter(new FileWriter(logFileName));
} catch (IOException ioe) {
ioe.printStackTrace();
}
pw.println("# --------------------------------------------");
pw.println("# LOG FILE : " + logFileName);
pw.println("# START TIME : " + startTime);
pw.println("# --------------------------------------------");
pw.println();
}
/**
* Used to flush and close the log file. This method MUST be called in
* order for all data to be flushed and saved to the log file.
*/
public void stop() {
stopTime = Calendar.getInstance().getTime();
long diff = stopTime.getTime() - startTime.getTime();
pw.println();
pw.println("# --------------------------------------------");
pw.println("# << END OF LOGFILE >> ");
pw.println("# --------------------------------------------");
pw.println("# STOP TIME : " + stopTime);
pw.println("# ELAPSED TIME : " + (diff / (1000L)) + " seconds.");
pw.println("# --------------------------------------------");
pw.close();
}
/**
* Used to write a given String object (without a newline) to the log file.
* @param logFileName Name of the path/logfile to create.
*/
public Logger1 (String logFileName) {
this.logFileName = logFileName;
}
}
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References.
The list of classes which were used on this page you can find below. The
links to Java API contain official SUN documentation about all used classes.
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