class constants instance constants..... etc

i need some brief explanation about these types of data values.... just a little bit of understandable explanation about these...

for example

private static final int FIRST_NUMBER = 1; //this is a class constant

but the book that i've red says that if THIS constant variable declared as..
like this..

private final int FIRST_NUMBER = 1; //then this is an instance constant

every instances of the class will have the same value


i dont get this point...

just a little bit of understandalbe explanation.

These two lines have one difference and that is the static keyword.

A static variable exists only once per class, if the variable was not final you could change it in one reference of the class and it would change in the other class as well.

See What does the 'static' keyword do in Java? - Stack Overflow

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