Is this possible?

[A Harry]

It it possible to get the current source code line number in order to output is as follows?

System.out.println("debug line output @ line no = " + lineNo);

thanks in advance!

harry

[Joanne Neal]

If you print the stack trace of an Exception, line numbers are included, so it would appear it is possible. Try looking at the source code for the Exception class to see how it is done there.
The JDK installation includes the source code in a file called src.zip.

[Murali Mohan]

I will tell you a naughty way to do this.
in a try block throw an exception. Then catch that there only. then parse the stack trace to get the line number. Oh now you got the line number. Do whatever you want ( +2 , -2 )

How is it?

[Jesper de Jong]

Yes, it is possible, but you should not try to invent your own logging framework.

Why not use a popular existing logging package such as Log4J, which you can configure to do this automatically?

[Joanne Neal]

Originally posted by Murali Mohan:
I will tell you a naughty way to do this.
in a try block throw an exception. Then catch that there only. then parse the stack trace to get the line number. Oh now you got the line number. Do whatever you want ( +2 , -2 )

How is it?

You don't actually need to throw and catch the exception. Just create one and you can then retrieve the stack trace from it.

[Ankur Sharma]

Originally posted by A Harry:
It it possible to get the current source code line number in order to output is as follows?

System.out.println("debug line output @ line no = " + lineNo);

thanks in advance!

harry

Here is an example:

public class Sample {
public static void main(String args[]) {
try {
int a = 10, b = 0, c;
c = div(a, b);
System.out.println("C:  " + c);
} catch (Exception e) {
StackTraceElement[] stck = e.getStackTrace();
for (int i = 0; i < stck.length; i++) {
System.out.println(
" stck[" + (i + 1) + "]:= " + stck[i].getLineNumber());
}
}
}
public static int div(int a, int b) {
return a / b;
}
}

And also the output is.

stck[1]:= 16
stck[2]:= 5

Hope it helps you out..

[Ernest Friedman-Hill]

Note that in recent versions of Java, the exception object isn't needed. Just call Thread.currentThread().getStackTrace() to get an array of StackTraceElement objects.

[Ankur Sharma]

Originally posted by Ernest Friedman-Hill:
Note that in recent versions of Java, the exception object isn't needed. Just call Thread.currentThread().getStackTrace() to get an array of StackTraceElement objects.

I don't think so is it possible in JDK 1.4