NonStop Server for Java 7.0 Tools Reference Pages

Basic jdb Commands
The following is a list of the basic jdb commands. The Java debugger supports other commands,
which you can list by using the jdb help command.
{help | ?}
Displays the list of recognized commands with a brief description.
run
After starting jdb and setting any necessary breakpoints, you can use this command to start the
execution of the debugged application. This command is available only when jdb launches the
debugged application (as opposed to attaching to an existing Java VM).
cont
Continues execution of the debugged application after a breakpoint, exception, or step.
print
Displays Java objects and primitive values. For variables or fields of primitive types, the actual
value is printed. For objects, a short description is printed. See the dump command below for
getting more information about an object.
NOTE: To display local variables, the containing class must have been compiled with the javac
-g option.
print supports many simple Java expressions including those with method invocations, for example:
• print MyClass.myStaticField
• print myObj.myInstanceField
• print i + j + k (i, j, k are primitives and either fields or local
variables)
• print myObj.myMethod() (to print the value if myMethod() returns a
non-null)
• print new java.lang.String("Hello").length()
dump
For primitive values, this command is identical to print. For objects, it prints the current value of
each field defined in the object. Static and instance fields are included.
The dump command supports the same set of expressions as the print command.
thread
List the threads that are currently running. For each thread, its name and current status are printed,
as well as an index that can be used for other commands, for example:
(java.lang.Thread)0x1 main running
In this example, the thread index is 4, the thread is an instance of java.lang.Thread, the
thread name is main, and it is currently running.
thread
Select a thread to be the current thread. Many jdb commands are based on the setting of the
current thread. The thread is specified with the thread index described in the threads command.
where
where with no arguments dumps the stack of the current thread. where all dumps the stack of
all threads in the current thread group. where threadindex dumps the stack of the specified
thread.
30 jdb: Java Debugger