Java for Fucking Idiots: Learn the Basics of Java Programming Without any experience!

class
StatusScreen {
private
Order
order
;
private
Networker
networker
;
public void
showOrderStatus() {
String currentStatus =
networker
.getOrderStatus(
order
.getId());
updateProgressBar(currentStatus);
}
private void
updateProgressBar(String status) {
//update order progress bar

}

---

}
private is saying that no other class knows how to update the progress bar
on the screen. Only the StatusScreen can call this method. It’s invisible to
the rest of them. Consider private properties and methods to be what is
“abstracted away” from the classes that would interact with it.
public is saying that any other class can call this method. It’s possible we’d
have another part of the user interface that wants to tell this screen to show
the order status. And luckily for us, it would appear that Networker’s
getOrderStatus
method is public, since we’re able to use it.
And that’s correct; this is what Networker might look like:
public class
Networker {
public
String getOrderStatus(String id) {
establishNetworkConnection();
makeRequest();
processResult();
return
getStatusFromResult();
}
private void
establishNetworkConnection() {}
private void
makeRequest(String id) {}
private void
processResult() {}
private
String getStatusFromResult() {}
}
We get to call the public method 
getOrderStatus
from our user interface
class. And we have no idea that all this complicated networking shit is
happening under the hood.
This is the beauty of encapsulation; we’re forcing abstraction. Other classes
can’t fuck up our shit if they aren’t even allowed access to it.