The string that you're parsing needs to consist only of digits (0-9), because otherwise it makes no sense as an integer. You're trying to convert "rect x=" into a number, hence the error. I presume from your other thread you're probably calculating the substring the wrong way round - I would imagine you need the bit after "rect x=" to convert to an integer (though this is just a guess.)

thx for the help. Now it is really interesting, same line, changed the substring, and got this error: Exception in thread "main" java.lang.NumberFormatException: For input string: "0 "

try using the 'trim' method: " string ".trim() becomes "string"

That's probably because you're incorrectly changing the arguments to substring - you're probably adding one to the first parameter (or using the one parameter version of substring), rather than taking one from the second parameter. Doing so should remove the space. Alternatively, danpost's suggestion of using trim() should work just as well.

thank you for your help this works now; I was dumb and wrote instead of