Java exception handling and log4j configuration files

First, the program error

1. Warning: Yellow Line: Warning
2. Error: Resource class: System level (thread)/ Environment level (drawing)
3. exception: Compile level: Exception

Run Level: Exception-RuntimeException

Second, abnormal operation

1. Enter an unmatched exception: Inputmismatchexception
2. Arithmetic Exceptions: ArithmeticException:/By zero
3. Array subscript out- of-bounds exception: ArrayIndexOutOfBoundsException
4. number Format exception: NumberFormatException
5. NULL pointer exception: NullPointerException
6. there is no exception to the bytecode file: ClassNotFoundException
7. Wait a minute...

Third, exception handling

1. Throw :throw Exception /throws declaration exception
2. catch:try...catch...finally ...
3. Exception class Genealogy

Iv. log files

1. Create Folder Lib
2. Check in the log4j jar package
3. Adding a jar package to the compilation path (add tobuildpath)
4. Create configuration file:log4j.properties
5. Edit configuration information Open the Log4j.properties file, write in source

Log4j.rootlogger=debug, stdout,logfile

Log4j.appender.stdout=org.apache.log4j.consoleappender

Log4j.appender.stdout.target=system.err

Log4j.appender.stdout.layout=org.apache.log4j.simplelayout

Log4j.appender.logfile=org.apache.log4j.fileappender

Log4j.appender.logfile.file=jbit.log

Log4j.appender.logfile.layout=org.apache.log4j.patternlayout

log4j.appender.logfile.layout.conversionpattern=%d{yyyy-mm-dd HH:mm:ss}%l%F%p%m%n

Use

1. To create a Log object property in a class that requires logging information

Import Org.apache.log4j.Logger

Public Logger log = Logger.getlogger ( class name . Class.getname ());

Log.error (String errmessage);

Log.error (String errmessage, Exception e);

Java exception handling and log4j configuration files