Static and final keyword questions

Question

Brief summary: I want to make the JButtons, JLabels, and JPanels public static final. Is that bad, and why? And what the heck is the Java system doing when it compiles and runs a program that does this? Is the code more efficient?
More questions below.....
I'm new to making GUI designs with Java. I am going to school and my teacher is making us do GUI interfaces in JAVA.
Early on, I learned that constants are identifiers similar to variables except that they holda particular value for the duration of their existence. QUESTION ONE: what happens during run-time, how does JAVA handle this constant?
I also learned that some methods may be invariant, as with a simple extension. These methods should be marked final. The subclass inherits both a madatory interface and a mandatory implementation. So I guess you use a final method when you want to model to a stric subtype relatinoship between two classes. All methods not marked final are fair game for re-implementation.
Well, that's good and well. So then I started thinking about static. That's a keyword in Java and when used with a variable, it's shared among all instances of a class. There is only one copy of a static variable for all objects of a class. So then again, I noticed that the programs in my book that used final usually threw in the word static before it. Memory space for a static variable is established when the class that contains it is referenced for the first time in a program.
Well, that too is great? Question 2: In my GUI programs, can I declare all the buttons (JButtons), labels (JLabels), panels (JPanels) as being final constant static?
In the program I don't intend to change the type of button, or JPanel so why not make it a constant? As long as I'm doing it, why not make it static? WHAT IS ACTUALLY GOING ON THEN IN MY PROGRAM WHEN I DO THIS?
Question 3: What goes on in JAVA when I make a method or function public static final. Is that what the Math class does? How is that handled during run-time? Is the code faster? Is it more efficient?
Question 4: If I make a class final, that means a subclass cannot extend it? Or does it mean that a subclasss cannot change it? I know that if the function or method in the parent class was final, then the subclass inherits both a madatory interface and a mandatory implementation....So if the class is final, then what?

Answer 1

You have a lot of questions..
You make a method final if it should not be allowed for subclasses to override it.
If you make a class final, you will not be able to subclass that class.
A static method is a class method, i.e. you don't need to create an instance of the class to call the method.
You can make any object and primitive final, but for objects, you are still able to modify what is inside the object (if there is anything you can and are allowed to modify), you just can't change the final reference to point to another object.
When you make a variable final, you sometimes make them static as well if they should work like constants. Because there is no reason that every instance of the class has their own copy of constants.
If you make everything static, why even bother to work with object-oriented programming. It gives you no reason to make instances of your classes. You should try not to make static variables and methods when there is no need for it. Just because you start from a static main method, it doesn't mean it is necessary to make all variables and methods static.
Don't think so much about performance issues as long as you are still learning java. When you make a method final, it is possible for a compiler to inline that method from where you call the method, but you will hardly gain much in performance with that. In most cases it's better to optimize the code you have created yourself, e.g. look at the code you run inside loops and see if you can optimize that.