Log4j and System.out.println

I have to implement log4j onto a running application, the whole application uses System.out.println for logging.
Can implement log4j without changing the code.
Regards,
Sabari

Create a PrintStream which writes to log4j. Make sure the PrintStream writes to the current System.out if called when it is already being called.
Set this as the default out and err with System.setOut() and setErr().

Similar Messages

Intercepting System.exit() and System.out.println() calls

hi there,
I have often problems when working with code that uses System.exit() and System.out.println() extensively, because it becomes difficult to debug.
Basically I do have wrappers for System.exit() (my own static exit function) and for System.out.println() (log4j).
Still not all programmers are using these methods; Probably the only way to enforce this is some kind of code warrior, but I was hoping to be able to intercept the two System.XXX calls (and throw an appropriate Exception). is this possible ??

Why not simply make your own security manager andhandle checkExit() and checkWrite?
Does anyone have a simple example of this? Please?System.exit() can be intercepted using a security manager, but not System.out.xxx.
Here is a short example:
//set your security manager
static{
     SecurityManager s = new OwnSecurityManager();
     System.setSecurityManager(s);
//redirect the out stream
try{
     PrintStream ps = new PrintStream(new FileOutputStream("output.txt"));
     System.setOut(ps);
}catch(IOException ioe){
     ioe.printStackTrace();
//some tests
System.out.println("Test");
System.exit(2);
//your security manager
class OwnSecurityManager extends SecurityManager{
     public void checkExit(int code){
       if(code > 0){
         super.checkExit(code);
         throw new SecurityException("Not allowed here->" + code);
     public void checkRead(FileDescriptor fd){
     public void checkRead(String file){
     public void checkRead(String file, Object context){
     public void checkPermission(Permission perm){
       if(perm.getName().equals("exitVM")){
         System.out.println("exitVM");
}

System.out.print and System.out.println

is it true that the System.out.print("\n") will print a new line character in all platforms?
in other words is it ok to assume that System.out.print("\n") and System.out.println(); will give the same output regardless of platform?

System.out.print("\n") Chances are that will produce different results on different platforms as some platforms use \n, some use \r some use \n\r (or is it \r\n?).
The question is why do you care when System.out.println() will do what you want? An alternative:
System.out.print(System.getProperty("line.separator"));

Difference between " system.out.print( ) " and " system.out.println( ) "?

Hi frnds, i m a beginner in JAVA today only started with the complete refrence....can you help me and tell the the Difference between " system.out.print( ) " and " system.out.println( ) "?

Rashid2753 wrote:
hi,Yes. But it's a good idea for new Java programmers to become accustomed to using helpful resources like the API Javadocs because it's much faster then waiting for replies everytime you have a question. For experienced developers the API Javadocs are an indispensible resource.

How do you change system.out.println colour?

Hi, I am developing some basic rmi client/server applications, I have an 2D array on a central server being read/written by remote clients. all the development is using system.out. statements at the moment (hopefully being replaced by GUI later) my question is when a client remote calls a read operation, and reads an array location, eg x3, y4 I want to print the location contents in a different colour to indicate the read, at the moment the displayArray() simply has nested for loops to cycle through the array and System.out.println statements to get it to the screen. I wonder is there a simple way to change the colour of system.out type statements? thanks for any help

I could be wrong, but I don't think that is possible. The System.out and other streams are just streams of characters, and doesn't contain any data about the characters. You could possibly get it to work if you knew which terminal the stream was going to and if the terminal had escape commands that could set colors. BBS browsers have that functionality, but I think that would be a hard path to follow.
If you are printing out a lot of data and need some color to aid it's readability, try printing directly to your graphic context:
Graphics g = getGraphics();
g.setColor(Color.white);
g.drawString("Hello",100,100);

System.out.println and Network Adapter problem

Hello,
I am encountering a 2 strange problems. I have 2 oracle application server instances, one dev and one production.
The first problem is when I type System.out.println in the JSP's i am able to see the output in both \opmn\logs\oc4jinstance. But the System.out.println in the java classes or bean show up only in development logs but not in production box.
Is there a setting I am missing here?
The second problem is on our development machine the application works fine, but as soon as we deploy the application on production I encounter:
could not open new connection: Io exception: The Network Adapter could not establish the connection
I have a class called DBUtils, which uses a 3rd party library to get connections from the connection pool as below. Using JSP I call the getConnection(). On my dev Oracle Application Server Instance it works fine, but on production I get the error. Can it be there is a setting that I am missing on the production box?
When I use a JSP and connect to the database without using the DBUtil class. I can connect to the database fine. Also using the DBUtil class with production oracle IP address on the development machine lets me connect with no problem, but production machine does not let me.
public class DBUtils {
static ConnectionPoolBean pool;
static {
System.out.println("DBUtils() - before connection pool bean");
pool = new ConnectionPoolBean();
pool.setDriverClassName("oracle.jdbc.driver.OracleDriver");
pool.setdbURL("jdbc:oracle:thin:@IPADDRESS:PORT:SID");
pool.setUser("USERNAME");
pool.setPassword("PASSWORD");
pool.setInitialConnections(1);
pool.setIncrement(1);
pool.setSoftMaxConnections(40);
public static Connection getConnection() throws SQLException {
System.out.println("Getting Oracle Connection");
return pool.getConnection();
public static void returnConnection(Connection conn) throws SQLException {
System.out.println("Returning Connection");
pool.returnConnection(conn);
Thanks for your help in advance.

Hi
System.out.println is a method of PrintStream in IO which is used to print the output on console in java progs.Here in jsp ,the o/p is printed on server's console window.But out.println is totally different as, out is implicit object derived from JspWriter and is used sly to PrinWriter 's object is used in servlets.It's work is to write upon Browser.
System.out.println() is normally used in jsp for debugging purposes only.
Ashish

What is the different between System.out.println and out.print

we move a project , jsp form to servlet to mysql db
suddenly we get Chinese input problem
on meantime only Thing I know is
if( chineseName!=null) {
                       chineseName= new String( chineseName.getBytes("ISO-8859-1"),"UTF-8");
                     out.print(chineseName); //display Chinese
                      System.out.println("Hello1"+chineseName ); // display unread symbol
             }I don't know why when we insert the value into db by StudentInsert(university_ID, surName, english_Name, chineseName, Address)
the db get the value from System.out.println
what setting decide my out put through System.out.println

Thank you for the reply!
after two days of search and guess.... I found out
for Web application , which under glassfish , you need to put your jsp page under WEB-INF,
other wise the server jsp turn your Chinese character that come from jsp request form to UTF8 symbol.
not ideal how to change the configuration in glassfish yet!

System.out.println and EJBs

Hi,
I'm trying to develop an application that has 2 main components:
1) A stateless session EJB, which is called by the container timer service periodically and makes some DB uptades.
2) A servlet which basically calls the create method in the EJB.
I've implemented a prototype of the app and the servlet code looks like this:
try {
Context context = new InitialContext();
MyClassLocalHome home = (MyClassLocalHome)PortableRemoteObject.narrow(
               context.lookup("java:comp/env/ejb/MyClass"),
          MyClassLocalHome.class);
System.out.println("Narrowed");
MyClassLocal timer;
// create a new instance
timer = home.create();
System.out.println("Created!");
In the ejbCreate() in MyClass callback, all I have is a System.out.println("ejbCreate() called") to show the method was called.
My problem is the even though the servlet code runs without errors and I can see the output in the application server's SystemOut.log, I can't find "ejbCreate() called" message. Am I looking in the wrong place? Am I doing something wrong?
Thanks in advance.
Pedro

Hi Pedro,
You're not necessarily doing something wrong. Where are you actually invoking a business method on the Stateless Session bean? In the Stateless Session Bean lifecycle, the actual bean instance creation is not required to be linked to the Home.create() call. That's because Stateless Session bean instances have no client-specific state. The container can delay the bean instance creation until an actual business method is called. Only then would the bean instance's ejbCreate method be called.
--ken

System.out.println and OAS

Hello All,
I have few System.out.println statements in my J2EE application which is running on OAS. I'm not sure where it is writing. I couldn't find anything in the server.log. Really appreciate any ideas.
Thanks

I know this is a couple of months old but it's a useful tip for anyone else having the same problem.
You can't see the System.out.println statements in any logs through the administration web pages of the OAS. You have to go through the filesystem, which is annoying and in my opinion a massive error by Oracle. But never mind.
The filepath is:
%ORACLE_HOME%/opmn/logs/default_group~***~default_group~1.log
replace *** with the name of your oc4j instance
HTH
Paul

System.out.println and out.println

Sir,
i wana know the diff between System.out.println() and println plz help in this regard. how they work in jsp .
thanks

Hi
System.out.println is a method of PrintStream in IO which is used to print the output on console in java progs.Here in jsp ,the o/p is printed on server's console window.But out.println is totally different as, out is implicit object derived from JspWriter and is used sly to PrinWriter 's object is used in servlets.It's work is to write upon Browser.
System.out.println() is normally used in jsp for debugging purposes only.
Ashish

System.out.println() and System.err.println()

Can any one tell me the difference between System.out.println()
and System.err.println() ?

Can any one tell me the difference between
System.out.println() Sends the output to the 'stdout' stream
and System.err.println() ?sends the output to the 'stderr' stream.
http://en.wikipedia.org/wiki/Standard_input

Difference between System.out.println() and out.println()

Hi,
In JSP we want to write the JNLP file contents to a ouput stream using "out.printl()".
The content of the JNLP file i am having in a String.
The "System.out.println()" is printing the correct JNLP file contents but "out.println()" writing wrong contents which are taken from Server JNLP file.
How to solve this problem?
Please guide me in this.
Thanks and Regards:
Dheeraj

Where is the "System.out.println()" running from? I don't think your problem has anything to do with the difference between System.out.println and out.println. Both methods print what is passed to them. It sounds like you are printing two different files because you are running in two different environments.
JSPs run on a server and only have access to files on the server or on a network the server is on. If you are trying to print a file on a user's system, JSP can't do it.

Difference between System.out.println(..)and PrintWriter.println(..)

Hello every one
With System.out.println(..) we can print to Console.
But System.out internally creates PrintWriter object.So why cant we use
PrintWriter.println(..) directly to write to console.
Is there aany disadvvantage with PrintWriter.println(..).
If so can anyone please tell me what is that and
what is the advantage we r going to get with System.out.println(..) method of writing to console.

kirn291 wrote:
With System.out.println(..) we can print to Console.If you want to be very precise, then you have to say that System.out.println() writes to the default output stream. This is usually shown at the console, but can equally well go into a file (if you've redirected it) or nowhere (when running without a console).
But System.out internally creates PrintWriter object.Not exactly. It refers to a PrintStream object.
So why cant we use
PrintWriter.println(..) directly to write to console.Because if you create a PrintWriter it is just another PrintWriter that writes to whatever you specified at the constructor. It is not the same thing as the one PrintStream that is used in System.out.
what is the advantage we r going to get with System.out.println(..) method of writing to console.The advantage is that it's the only way to do it. Could you post an example of how you'd think of a different way to write to the console?

System.out.println and log file

          I am developing jsp on BEA Weblogic 613 on Solaris.
          What if i run the following statement
          System.out.println("Hello world");
          I understand that Hello World will be printed to the server console. I do not
          have access to this console. Is there any log file or temporary log file it gets
          sent to? If not, is there anyway to redirect output from the console to someplace
          else?
          Thanks!


You can redirect console output for stdout on Solaris like so:
          java weblogic.Server > consoleoutput.txt
          then in a terminal window you can see whats going on with
          tail -f consoleoutput.txt
          Sam
          Brian Schneider wrote:
          > I am developing jsp on BEA Weblogic 613 on Solaris.
          >
          > What if i run the following statement
          > System.out.println("Hello world");
          >
          > I understand that Hello World will be printed to the server console. I do not
          > have access to this console. Is there any log file or temporary log file it gets
          > sent to? If not, is there anyway to redirect output from the console to someplace
          > else?
          >
          > Thanks!

Tomcat Servlet: System.out.println in servlet not printing to catalina.out

Hello friends ,
When i m using System.out.println() in servlet its o/p should come in catalina.out but its not coming plz help me....one thing more can we replace exixting catalina.out file with new one...
please Help me soon.
Thanks

go to[u] TOMCAT_DIR/config/server.xml.
Open this xml file and find something like <Logger className="org.apache.catalina.logger.FileLogger"
              prefix="catalina_log." suffix=".txt"
              timestamp="true"/>and
<Logger className="org.apache.catalina.logger.FileLogger"
                 directory="logs" prefix="localhost_log." suffix=".txt"
            timestamp="true"/>You can change the log file name to another one.
It's much better to use a logger tool like log4j (http://logging.apache.org/log4j/docs/download.html) then using a System.out.println()...
hope that helps

Log4j and System.out.println

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