jgrasp handbook

DRAFT, February 18, 2003, Page 102
Watches: Fields can be watched for access or modification if the target JVM supports it. To create a
watchpoint, select a field and then right click. A popup menu will allow you to set a modification or access
watchpoint, or to remove them if they are set. A "Watch All" will set a watchpoint on all fields of the same
signature as the selected field (including those in subclasses and superclasses of the field's object type).
A simple "Watch" will set a watchpoint only for the selected field's object. Fields that are being watched
for modification are shown with a black triangle pointing up in the center of the icon, those with an access
watch are shown with the triangle pointing down, while those with both will have a black square. Setting a
lot of watches can slow down debugging.
19.6 Breakpoints
Breakpoints can be set in the CSD windows using the "View" / "Breakpoints" menu, or the context menu.
Only breakpoints in CSD Windows are active (when a CSD Window is closed, the breakpoints will go
away, when one is opened, the breakpoints will become active. Breakpoints can be added or removed
while the debugger is running.
While the debugger is running, invalid breakpoints (breakpoints set on lines that do not contain
executable code) are shown crossed out. If the class files for a particular source file can not be found, the
breakpoints are shown with a slash through them. In order for this mechanism to work, the source file and
associated class files must be located in the same directory.
20 Complexity Profile Graph (CPG)
The Complexity Profile Graph, or CPG, is a statement-level complexity or comprehensibility metric. Each
segment, which corresponds roughly to a program statement, is assigned a complexity that is a weighted
sum of:
Reachability - the number of conditions that must be evaluated to reach the segment from outside
of the enclosing method, function, or other top-level statement block. This is the traditional
definition of reachability.
Content - the log of the number of significant tokens in the segment. Some punctuation, such as
block-enclosing braces or a statement-ending semicolon, is not considered significant. A pair of
parenthesis is counted as one token.
Breadth - the number of statements, methods, etc. in the innermost block containing the segment.
Inherent - value assigned based on the inherent complexity of the innermost enclosing structure.
For example, segments in switch or case statements are assigned an inherent complexity of 3.0.
This reflects the view that some structure types are inherently more complex than others.
The CPG window "Data Sets" menu allows any combination of these values and the total complexity to
be viewed.
Currently, the CPG is implemented only for Java and Ada.
21 CPG Window
The main section of this window shows the complexity values for the currently selected data sets. If the
source is unedited, selecting segments in the CPG window will select the corresponding text in the source
CSD window, and vice versa. The selection in the CPG window is shown as a yellow background. If the
source is unedited, a black rectangle shows the segments that are currently visible in the CSD Window.