Topics discussed: Access modifiers, public, private, static
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Access modifiers
Access modifiers are our way of sectioning off our program and making it harder to accidentally use / misuse methods not contained within the calling class. There are 4 access modifiers and they basically work like this:

    1. Public: Public as an access modifier means that the ANYTHING can call on your class / function. This means that anyone / any function can call it for any reason, we’ll see why that’s a problem later on.
    2. Protected: (Also known as package-private) Protected is where methods cannot be called by anything outside of same package / class / subclass as where the call originated from.
    3. not specified: Same as Protected.
    4. Private: Only accepts calls from within the class / object.

Using public as an access modifier
When we use public as an access modifier, the entire program can call upon our methods / objects if they are familiar with our interface. We might get into external calls at a much later lesson but for now let’s look at internal same-project calls:

/////  Javafile.java /////
int x= 1, y=7;

//the syntax to call a public method in another file is methodFile.methodNamesum = methodFile.sum(x,y)

/////methodFile.java/////
public static int sum(int x, int y){
    return (x+y);//Will return the sum of x+y to Javafile.java
}

Using private as a modifier
If you’re in doubt about whether or not you should be using private as a modifier, you should be using private as a modifier. When we get into larger programs in the future with 4 or 5 different files, data will be moving all over the place, and controlling the flow of that data is extremely important.  But beyond that, it becomes crucially important when dealing with objects that we don’t accidentally overwrite parts of them and controlling how people interact with them becomes crucial.


Last modified: April 10, 2019

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