jdb-quickstart.txt

This is an ultra quick start to jdb

Hopefully you are a little familiar with gdb, since jdb resembles it lightly.

Notable differences:

- a breakpoint is set with "stop in <class>.<method>" or "<class>:<line>".
- no tab completion
- no readline (cursor up/down)
- no shortcuts; you have to write "run", not "r" to run the program
- no listing files before the class was loaded
- much easier method to specify the location of the source: "use <dir>"
- "until" is "step", "step" is "stepi"

Okay, so here you go, a little demonstration:

$ ./ImageJ --jdb
> stop in ij.ImageJ.main
Deferring breakpoint ij.ImageJ.main.
It will be set after the class is loaded.
> run
run ij.ImageJ
Set uncaught java.lang.Throwable
Set deferred uncaught java.lang.Throwable
>
VM Started: Set deferred breakpoint ij.ImageJ.main

Breakpoint hit: "thread=main", ij.ImageJ.main(), line=466 bci=0

main[1] use .
main[1] list
462             //prefs.put(IJ_HEIGHT, Integer.toString(size.height));
463     }
464
465     public static void main(String args[]) {
466 =>          if (System.getProperty("java.version").substring(0,3).compareTo("1.4")<0) {
467                     javax.swing.JOptionPane.showMessageDialog(null,"ImageJ "+VERSION+" requires Java 1.4.1 or later.");
468                     System.exit(0);
469             }
470             boolean noGUI = false;
471             arguments = args;
main[1] print args[0]
java.lang.IndexOutOfBoundsException: Invalid array range: 0 to 0
 args[0] = null
main[1] print args.length
 args.length = 0
main[1] step
>
Step completed: "thread=main", ij.ImageJ.main(), line=470 bci=28
470             boolean noGUI = false;

main[1] step
>
Step completed: "thread=main", ij.ImageJ.main(), line=471 bci=30
471             arguments = args;

main[1] set noGUI = true
 noGUI = true = true
main[1] cont
>
The application exited