如何检查Java中的文本字段中是否输入了某个值

Question

Does anyone know how to check whether someone entered something in a textfield in java which isn't allowed (depending on my requirements)?

It is my intention that no special characters can be entered, but now it's possible to enter "=true" (according to the function, it then satisfies, because it returns a true). I've written a function to check whether the username is correct or not.

Answer 1

I have already solved it. I made a string variable that retrieves the entered text and add a trim() and toLowerCase() function. Then I check if the entered value is equal to certain values and if it contains some special chars. For me it's works well now.