Java Debugging from Command Line

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Apr 22nd, 2006 09:12 Knud van Eeden, ---------------------------------------------------------------------- --- Knud van Eeden --- 22 April 2006 - 04:11 pm ---------------------- Java: Debug: How to debug on the command line? [jdb.exe] === To debug, run e.g. the program jdb.exe === Steps: Overview: 1. -Possibly download and install the Sun Java JDK (because this installs also the program jdb.exe) 2. -Run the program jdb.exe 3. -This will open a command line where you can type debug commands 4. -E.g. run [myApplicationFilename].java e.g. run HelloWorldApplication.java 1. -That will show a screen output similar to the following: --- cut here: begin -------------------------------------------------- > run HelloWorld.java Set uncaught java.lang.Throwable Set deferred uncaught java.lang.Throwable VM Started: Exception occurred: java.lang.ClassNotFoundException (uncaught)"thread=main", java.net.URLClassLoader$1.run(), line=199 bci=72 main[1] --- cut here: end ---------------------------------------------------- 5. -For a list of commands, type help 1. -That will show a screen output similar to the following: --- cut here: begin -------------------------------------------------- jdb.exe Initializing jdb ... > help ** command list ** run [class [args]] -- start execution of application's main class threads [threadgroup] -- list threads thread -- set default thread suspend [thread id(s)] -- suspend threads (default: all) resume [thread id(s)] -- resume threads (default: all) where [ | all] -- dump a thread's stack wherei [ | all]-- dump a thread's stack, with pc info up [n frames] -- move up a thread's stack down [n frames] -- move down a thread's stack kill -- kill a thread with the given exception object interrupt -- interrupt a thread print -- print value of expression dump -- print all object information eval -- evaluate expression (same as print) set = -- assign new value to field/variable/array element locals -- print all local variables in current stack frame classes -- list currently known classes class -- show details of named class methods -- list a class's methods fields -- list a class's fields threadgroups -- list threadgroups threadgroup -- set current threadgroup stop in .[(argument_type,...)] -- set a breakpoint in a method stop at : -- set a breakpoint at a line clear .[(argument_type,...)] -- clear a breakpoint in a method clear : -- clear a breakpoint at a line clear -- list breakpoints catch [uncaught|caught|all] | -- break when specified exception occurs ignore [uncaught|caught|all] | -- cancel 'catch' for the specified exception watch [access|all] . -- watch access/modifications to a field unwatch [access|all] . -- discontinue watching access/modifications to a field trace methods [thread] -- trace method entry and exit untrace methods [thread] -- stop tracing method entry and exit step -- execute current line step up -- execute until the current method returns to its caller stepi -- execute current instruction next -- step one line (step OVER calls) cont -- continue execution from breakpoint list [line number|method] -- print source code use (or sourcepath) [source file path] -- display or change the source path exclude [, ... | "none"] -- do not report step or method events for specified classes classpath -- print classpath info from target VM monitor -- execute command each time the program stops monitor -- list monitors unmonitor -- delete a monitor read -- read and execute a command file lock -- print lock info for an object threadlocks [thread id] -- print lock info for a thread pop -- pop the stack through and including the current frame reenter -- same as pop, but current frame is reentered redefine -- redefine the code for a class disablegc -- prevent garbage collection of an object enablegc -- permit garbage collection of an object !! -- repeat last command -- repeat command n times help (or ?) -- list commands version -- print version information exit (or quit) -- exit debugger : a full class name with package qualifiers : a class name with a leading or trailing wildcard ('*') : thread number as reported in the 'threads' command : a Java(tm) Programming Language expression. Most common syntax is supported. Startup commands can be placed in either "jdb.ini" or ".jdbrc" in user.home or user.dir