How to send a stacktrace to log4j?

Question

Say you catch an exception and get the following on the standard output (like, say, the console) if you do a e.printStackTrace() :

java.io.FileNotFoundException: so.txt
        at java.io.FileInputStream.<init>(FileInputStream.java)
        at ExTest.readMyFile(ExTest.java:19)
        at ExTest.main(ExTest.java:7)

Now I want to send this instead to a logger like, say, log4j to get the following:

31947 [AWT-EventQueue-0] ERROR Java.io.FileNotFoundException: so.txt
32204 [AWT-EventQueue-0] ERROR    at java.io.FileInputStream.<init>(FileInputStream.java)
32235 [AWT-EventQueue-0] ERROR    at ExTest.readMyFile(ExTest.java:19)
32370 [AWT-EventQueue-0] ERROR    at ExTest.main(ExTest.java:7)

How can I do this?

try {
   ...
} catch (Exception e) {
    final String s;
    ...  // <-- What goes here?
    log.error( s );
}

Answer 1

You pass the exception directly to the logger, e.g.

try {
   ...
} catch (Exception e) {
    log.error( "failed!", e );
}

It's up to log4j to render the stack trace.