What is an instance variable?
A variable instance is a piece of data in object -oriented programming that has its own unique value for each object in which it is located. Variable instances can also be called instance members, non -static fields and data members. They are an important part of most objects that hold specific pieces of data that the object uses for calculation.
For example, if there are two objects, A and B, where object A has a variable instance called "Blah", and Object B also has a variable instance called "well -being", two "well -being" variants are different entities. Each variable is associated with an object that encapsulates it. The full name of the variable "blah" associated with object A is "A.Blah", while the full name of the variable "blah" associated with object B is "B.Blah". Everyone if these variables can have their own value. If objects A and B are of the same type, another object of this type is created, and Object C will also have a variable "blah" instance, which can have it with its own unique value.
They are often confused with static variables, but both differ significantly. Unlike variable instances, each of which has a particular type of type of static variables, they have only one value and this value is the same for each object of a suitable type. Static variables are often called class variables that are not the same as instance variable.
Depending on the characteristics of the visibility assigned to them, instances can only be visible only within a particular object, object and its subclass or to the object in which it is located, as well as any other objects. This final type of visibility, called public visibility, is often considered to be a poor practice, for example, variables, because it is easy to break the principles of encapsulation in object -oriented programming. Despite this taboo, there are times when public installation Nce is useful. For example, many standard classesIn Java, public instances have variable instances, which sometimes allows easy adjustment of properties.
The visibility of the instance variable also comes into play with inheritance. If one class inherits from another, both classes do not immediately access the variable instances of the other. The variables of private instances in SuperClass and the subclass remain limited to these classes, so the private variable in the subclass cannot be seen SuperClass and vice versa. The only variable instance that sees both supercar and subclass is protected variables in SuperClass.