Q:

Debugger doesn't show new variable in stack frame

Can someone tell me, why the debugger doesn't show variable j in stack frame(Using IntelliJ IDEA)? 
for (int i = 0 ;  i < 10; i++) {
        int j = 100;
    }

when i = 0, variable j should be created once, then, being removed from the stack, then i = 2, j should be loaded into the stack, but IntelliJ debug tool doesn't show the creation of j once, Where is the problem? Thank you
Screenshot:

There is a tool, please try it out https://cscircles.cemc.uwaterloo.ca/java_visualize/#

A:

This variable is not used and javac compiler optimizes the bytecode by completely removing it. You can add some usage for the variable, like log it so System.out and then you should be able to see it in the debugger.

