What are non static members in Java?

Answer 1

In programming, a nonstatic variable (also known as an instance variable) is a variable that is associated with a specific instance of a class, rather than with the class itself. Nonstatic variables are defined within a class, but they are created for each object (instance) of the class.

For example, consider the following class definition in Java:

class Employee {

String name;  // nonstatic variable

int age;      // nonstatic variable

static int count;  // static variable

// constructor and other methods go here

}

In this example, the name and age variables are nonstatic variables, while the count variable is a static variable. The name and age variables are associated with a specific instance of the Employee class, while the count variable is associated with the class itself, rather than with any particular instance.

Nonstatic variables are accessed using the this keyword in Java and other object-oriented languages. For example, to access the name variable of an Employee object, you could use the following code:

Employee emp = new Employee();

emp.name = "John Smith";

In this example, the name variable is being accessed using the emp object, which is an instance of the Employee class. If you had another object of the Employee class, such as emp2, it would have its own separate copy of the name variable, which could be different from the name variable of the emp object.

Static variables, on the other hand, are shared among all instances of a class. They are defined using the static keyword, and they are accessed using the name of the class, rather than using an object reference. For example, to access the count variable in the above example, you could use the following code:

int c = Employee.count;

Answer 2

Local variables (on the stack) or dynamically allocated variables (in the heap) are nonstatic variables. Static variables, constants and globals are all allocated in the program's data segment.

Answer 3

Non-static member variables are local to an object (an instance of a class). Each object has its own unique set of non-static member variables. Conversely, a static member variable is local to the class itself. There is only one instance of each static member variable per class, regardless of how many objects are instantiated from that class.

Answer 4

Non-static members are otherwise known as instance members. Instance member variables are local to specific objects of the class and instance member methods have an implicit reference to "this" instance (the current instance of the class). Static members are local to the class rather than to objects of the class.

Answer 5

A static data member is a data member that is allocated in static memory and thus exists for the entire duration the program is running. Unlike a static variable (which is globally accessible), a static member is scoped to the class in which it is declared, and like any other member, can be declared with private, protected or public access. However, in the vast majority of cases, data members (both static and non-static) should be declared private in order to maintain encapsulation. If we require public access to a static data member, it is usually best to provide a public interface via a public static member function rather than to allow unchecked public access to the data itself.

Static member data is shared by all instances of the class. That is; it is local to the class rather than to an object of the class. However, being allocated in static memory, it can be made accessible (usually via a static member function) even when no instances of the class exist. Usually, static member data is used to provide a shared resource for all instances of the class.

As a simple example, the following class uses a static data member to maintain a count of all instances of the class:

class X {

static int count;

public:

X () { ++count; } // every constructor should increment the count

~X() { --count; } // the destructor decrements it.

static int get_count() { return i; }

};

int X::i = 0; // initialise the static data member

Note that all static data members must be initialised. As of C++11, that initialisation must be done outside of the class declaration, we cannot use in-class initialisation as we can with non-static data members. Typically, we place the initialiser in one of the class implementation files (never in a class header file).

Answer 6

Non static variables are specific to that instance of a class. Static variable is like a global variable and is available to all methods. Non static variable is like a local variable and they can be accessed through only instance of a class...

Answer 7

Local variables (on the stack) or dynamically allocated variables (in the heap) are nonstatic variables. Static variables, constants and globals are all allocated in the program's data segment.