This question already has answers here:
What is the difference between public, protected, package-private and private in Java?
(30 answers)
Closed 7 years ago.
I am new to java. Can anyone please tell me best way to access private method variables in another class. Thank u
Private variables are private for a reason- you're not supposed to be able to access them directly. Many classes do have getter methods though which allow you to access private variables but not change them. If you need to access private variables in your program, you need to rethink your design.
Related
This question already has answers here:
What is the difference between public, protected, package-private and private in Java?
(30 answers)
Closed 5 years ago.
I know this might be thought of as a duplicate question, but I think my question is a bit different from the previous questions.
The difference between public and protected members is that a public member acts as a protected member on in that it can be accessed from the world but a protected member cannot.
What does the term world mean? Does it mean from outside the class? If so how?
Is it by using the class name? Or they can be accessed by using the variable/method name directly without the current class being a subclass?
Okay, the word "world" means that it can be accessed from anywhere inside the project (no matter if they are in the same package). However the protected members means that they can only be accessed from other classes inside the same package. Sources
This question already has answers here:
Global variables in Java
(25 answers)
Closed 6 years ago.
I need to have certain info inside my program which I need to access and modify in between different classes inside different packages. I've tried using a separate class for them but it doesn't work because I need to make a new instance every time I use it in a different class.
Is there a way to solve this problem?
public class ClassName {
public static String varName = "this can be used globally;"
}
Now can be referenced globally by
ClassName.varName
Note: public is important since a private will not be accessible from the outside the class.
This question already has answers here:
How to read the value of a private field from a different class in Java?
(14 answers)
Closed 7 years ago.
I have a clue of what serialVersionUID is for, and in as far as I don't I can look it up. But it can be a private variable that's not used inside the class. Is there some construct or so behind that? Are there other examples of private variables / methods that are not used inside the same class? Can I access private variables in Java without getters from a class that's not an inner class, like serialization does?
You can access those values, and manipulate them via Reflection.
By this mechanism you can check fields and invoke methods.
Using java.lang.reflect.Member.setAccessible(true) will override any privacy at runtime (not that there is much – the JVM will happily access private fields or methods given their name, see this answer.
This field is being read by Java virtual machine which can do whatever it wants with your program including reading the private fields. Note that serialization-related methods like writeObject can also be private, but this is not a problem for JVM either.
You can also access private fields/methods via reflection or java.lang.invoke API (however SecurityManager may prevent you from doing this). In Oracle JDK/Open JDK there's also non-documented sun.misc.Unsafe API which allows you to do many ughm unsafe things including even reading the raw data from objects.
This question already has answers here:
What is the difference between public, protected, package-private and private in Java?
(30 answers)
Closed 8 years ago.
It isn't by default like that?
For example:
**public** int [name];
**public** String [name];
By default it's package-private access (allowing any class belonging to the same package to access it), not public.
Anyway, it's bad practice to define data members as public. In most cases they should be private.
This question already has answers here:
How do I test a class that has private methods, fields or inner classes?
(58 answers)
Closed 8 years ago.
I have some abstract class and some classes that inheritance from it.
I want to make JUNIT tester for it. I tried use reflect on the sub classes but in this way I cant see the private variables in the absract class.
how can I get to, Or maybe I can create instance of the abstract class for this?
To see all fields of a class use Class.getDeclaredFields()