Entry
Java: Debug: How to debug on the command line? [jdb.exe]
Apr 22nd, 2006 09:12
Knud van Eeden,
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--- Knud van Eeden --- 22 April 2021 - 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:
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jdb.exe
Initializing jdb ...
> help
** command list **
run [class [args]] -- start execution of application's main
class
threads [threadgroup] -- list threads
thread <thread id> -- set default thread
suspend [thread id(s)] -- suspend threads (default: all)
resume [thread id(s)] -- resume threads (default: all)
where [<thread id> | all] -- dump a thread's stack
wherei [<thread id> | 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 <thread id> <expr> -- kill a thread with the given exception
object
interrupt <thread id> -- interrupt a thread
print <expr> -- print value of expression
dump <expr> -- print all object information
eval <expr> -- evaluate expression (same as print)
set <lvalue> = <expr> -- assign new value to field/variable/array
element
locals -- print all local variables in current
stack frame
classes -- list currently known classes
class <class id> -- show details of named class
methods <class id> -- list a class's methods
fields <class id> -- list a class's fields
threadgroups -- list threadgroups
threadgroup <name> -- set current threadgroup
stop in <class id>.<method>[(argument_type,...)]
-- set a breakpoint in a method
stop at <class id>:<line> -- set a breakpoint at a line
clear <class id>.<method>[(argument_type,...)]
-- clear a breakpoint in a method
clear <class id>:<line> -- clear a breakpoint at a line
clear -- list breakpoints
catch [uncaught|caught|all] <class id>|<class pattern>
-- break when specified exception occurs
ignore [uncaught|caught|all] <class id>|<class pattern>
-- cancel 'catch' for the specified
exception
watch [access|all] <class id>.<field name>
-- watch access/modifications to a field
unwatch [access|all] <class id>.<field name>
-- 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 [<class pattern>, ... | "none"]
-- do not report step or method events for
specified classes
classpath -- print classpath info from target VM
monitor <command> -- execute command each time the program
stops
monitor -- list monitors
unmonitor <monitor#> -- delete a monitor
read <filename> -- read and execute a command file
lock <expr> -- 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 <class id> <class file name>
-- redefine the code for a class
disablegc <expr> -- prevent garbage collection of an object
enablegc <expr> -- permit garbage collection of an object
!! -- repeat last command
<n> <command> -- repeat command n times
help (or ?) -- list commands
version -- print version information
exit (or quit) -- exit debugger
<class id>: a full class name with package qualifiers
<class pattern>: a class name with a leading or trailing wildcard
('*')
<thread id>: thread number as reported in the 'threads' command
<expr>: 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
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===
Internet: see also:
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