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Java Java Objects (Retired) Harnessing the Power of Objects Methods and Constants

Mike B
Mike B
10,424 Points
Posted by Mike B
Mike B
10,424 Points

How are private variables changed without using the getVariable() methods?

In the pez dispenser example, we have set both the mCharacterName and mPezCount to private, but then we are able to set the value in the constructor class. I thought the purpose of setting a variable to private was so we can't directly access/change the value

2 Answers

David Lacedonia
David Lacedonia
13,627 Points
David Lacedonia
David Lacedonia
13,627 Points

The 'private' key protects the variable from the outside (of the object). You can open gates to that variable, with public methods (get/set).

In this case, the variable can be settled in the initialization because you want to set the variable when is created.

The purpose is that you can't access/change the variables with the dot notation: object.variable. Example: kart.color = "red"; So you create your set/get methods (if you want) to manipulate the variable, from the outside.

For example, your set method set the variable, just if the parameter length is bigger than 10. So you protect the variable from being setted with a short string.

(sorry for bad english)

Mike B
Mike B
10,424 Points
Mike B
Mike B
10,424 Points

I think I understand...thanks for the help.

Kelly Hughes
Kelly Hughes
2,444 Points
Kelly Hughes
Kelly Hughes
2,444 Points

Hi Mike,

I'm still working on grasping the use of the private access level modifier, but I believe that it is done to reduce the probability of error within the main code. This is due to the fact that private variables can only be accessed within their class. In contrast, a public variable can be used throughout the code, and this may increase the chance of syntax error.

The get() and set() methods are still within the code of Class, so they can access the private variables. As David said previously, you can consider them as a gateway to use the variable within the main code. You give the state of the object when creating it (Object objectReference = new Object(info);, the get() method can retrieve that info due to the intialization code within the Class constructor, and then it can return that info.

So, if you want to print something out to the screen: System.out.printf("Here's some stuff about %s\n", objectReference.getMethod()); will be allow the user to see it.

Also, a tip that I just found from the Oracle Java Tutorial:

We already learned that %s is for string, however - %d is for integer %f is for float and double

I hope that this helps!