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I catch NullPointerException but log4j does not print stack trace, I aspect number of line of exception occurred etc. what is wrong?
My log
20110412-101042,317[ Timer-7][R] Exception while processing for value: abc. [xyz.Dummy]
java.lang.NullPointerException
log4j.property file
log4j.rootCategory=ERROR, logfile
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%-5p %r [%t] : %m%n
log4j.appender.logfile=org.apache.log4j.RollingFileAppender
log4j.appender.logfile.File=my_application.log
log4j.appender.logfile.Append=true
log4j.appender.logfile.MaxBackupIndex =10
log4j.appender.logFile.MaxFileSize=40000KB
log4j.appender.logfile.layout=org.apache.log4j.PatternLayout
log4j.appender.logfile.layout.ConversionPattern=%d{yyyyMMdd-HHmmss,SSS}[%8.8t][%.1p] %-70m[%c{2}]%n
My snippet code
String value;
try {
value = "abc";
//... lots for code
}catch(Exception e) {
logger.error("Exception while processing for value: " + value + ". ", e);
}
360
The short answer is that all you have to do to print the stack trace of an exception using Java and Log4J (or the Apache Commons Logging project) is this: log. error("Your description here", exception); where exception is your Java Exception object.
Example: Convert stack trace to a stringIn the catch block, we use StringWriter and PrintWriter to print any given output to a string. We then print the stack trace using printStackTrace() method of the exception and write it in the writer. Then, we simply convert it to string using toString() method.
Using printStackTrace() method − It print the name of the exception, description and complete stack trace including the line where exception occurred. Using toString() method − It prints the name and description of the exception. Using getMessage() method − Mostly used. It prints the description of the exception.
The function printStackTrace() of the Exception class can take one parameter, either a PrintStream or a PrintWriter. Thus, it is possible, using a StringWriter, to print the stack trace into a String: StringWriter sw = new StringWriter(); PrintWriter pw = new PrintWriter(sw); e. printStackTrace(pw);
The problem is the %-70m in your Layout. It truncates the message, and therefore does not reach the stacktrace. Use %m as usual instead.
Even Better: Write a custom layout, this will work as you want.
111
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