The documentation for Eclipse states that a blue circle icon represents an
enabled line breakpoint
and that a checkmark is an
adornment that marks a line breakpoints as installed
What's the difference between active, installed and enabled, when referring to breakpoints? Is installed -- in this case -- an Eclipse-specific definition?
This thread (2002!) has a good explanation for installed breakpoints
Blue breakpoints mean that the breakpoint is not installed.
In older builds, a green icon means that the breakpoint was successfully installed.
An installed breakpoint means that the class has been loaded in the target VM and a breakpoint request has been successfully created at the desired location (for a line breakpoint) for the current debug target.In the current builds, an installed breakpoint is indicated with a small checkmark overlay icon on top of the blue "base" icon.
A breakpoint may not been installed:
- when the class is not loaded (or not yet loaded)
- our breakpoint location verifier fails to identify a non-executable line of code and lets you place a breakpoint on that line.
- when you run instead of debug.
As mentioned in jdt documentation:
- An enabled breakpoint causes a thread to suspend whenever the breakpoint is encountered. Enabled breakpoints are drawn with a blue circle
- A disabled breakpoint will not cause threads to suspend. Disabled breakpoints are drawn with a white circle
and have a checkmark overlay once successfully installed. A breakpoint can only be installed when the class the breakpoint is located in has been loaded by the VM.
.I think it's a breakpoint that's been compiled and is available next time you run.
Installed means that the program will indeed hit that break point when debugging.
来源：https://stackoverflow.com/questions/1799362/what-does-it-mean-for-a-breakpoint-to-be-installed