调试循环

Question

For some current projects, I'm working with several data structures that are pretty large (in the area of 10K elements). To be able to access this data in lists, I need to use loops and iterators, which can be a pain when the problem area is in the latter half of the list.

So I find myself spending alot of time with my finger on the F8 button in Eclipse's debugger to loop through each element of an iterating loop. This gets worse when have to step through that particular section several times to get an idea why the code is reacting a particular way.

If one has a general idea how many times a loop is to execute before a problem area is hit, is there a way to set a loop breakpoint to execute up to that point then pause?

Answer 1

Use conditional breakpoints.

http://wiki.eclipse.org/FAQ_How_do_I_set_a_conditional_breakpoint%3F

Answer 2

I believe there's a better way to do this, but you can create a trivial block of code in the loop that only executes at a certain iteration, and put the breakpoint inside of it.

if (loopIndex == 1000) {
  int number = 14;            //Break here
}

Answer 3

Using this as an example:

for(int i=0;i<10000;i++){
    System.out.println(i);
}

Set a breakpoint on the print line, then right click on it and select Breakpoint Properties... . From here you can set a condition to trigger the breakpoint. This is the similar to a conditional you would have in an if-statement. If you wanted to trigger the breakpoint when i equals 6000, check the Conditional box and try this: