line 25.
public void Window() is not constructor and is never invoked/executed. You may have to read/understand rules for constructors and how is it different from methods in more detail.
Its name should be exactly same as the class name and no return type mentioned. So your
public void Window() (if intent to be constructor) must be
public CalcWindow(). Remember constructor name must be CalcWindow() if class name is CalcWindow, case-sensitive.
There is an article
http://www.javaworld.com/article/2076204/core-java/understanding-constructors.html that might help understand how constructors differ from methods.