the use of private keyword

Question

I am new to programming. I am learning Java now, there is something I am not really sure, that the use of private. Why programmer set the variable as private then write , ge

Answer 1

Its considered bad mainly because you loose control over who can change the value and what happens when the value changes.

In tiny application written by you for you it won't seem that important but as you start developing for larger and larger applications having control over who changes what and when becomes critical.

Imagine from your example above, you publish library as is, other people use it, then you decide you wanted to calculate another value in your bad class when the size changes ... suddenly the bad00 class has no way of knowing and you can't change it because other people rely on it.

Instead if you had a set method you could extend it to say

void SetSize(int newSize)
{ 
   size = newSize;
   DoCalculation;
}

You can extend the functionality without breaking other peoples reliance on you.