Note that in your latest solution:

• src/main/java/BraceChecker.java:7: error: cannot find symbol ... appears when running your code (likely you forgot to import the corresponding library for that method or utility)

• Your while loop does not have any statements to execute. (Note that one line of code will not do anything)

• The final conditional checking in the return statement is wrong

There's something wrong with your loop condition. Try to find what it is.

Try your code with that input in Pythontutor

Your problem is probably related at mutating the list you're iterating through.