What is reference variable in java?

Answer 1

A reference is a memory address. In some languages, like C, memory addresses can be stored in pointer variables. Thus a pointer is a reference variable. They are said to point to the memory address, and allow indirect access to that memory address. Since they are variable, they can be re-assigned (unless declared constant, in which case they are not variable).

However, in other languages, like C++, a reference is neither a pointer nor a variable -- it is an alias, an alternate name for an already existing object. References have no storage of their own thus they cannot be reassigned once initialised. In that respect they are like constant pointers. However, since they have storage of their own, there is no need to use indeirection. It's a bit like referrring to someone named William as Bill, Billy or Will -- they're all alternate names (aliases) for the same person.

Answer 2

Reference variable is used to create an alias name for a previously defined variable. Its use is that the same data object can be referred by two names and then these names can be used interchangeably.

Answer 3

References are aliases, alternate names for objects that already have a name. They allow us to refer to an object by more than one name. This makes it possible for functions to refer to an object argument through a reference. The function uses one name for the object while the object itself has its own name. This is really no different to the way Bill and Billy can be references to someone named William. They all refer to the same person.

Not all languages support references. For instance, C has no concept of a reference, but it does have pointer variables. Pointers store memory addresses, thus any object that has an addressable identity can be referred to by that address. Thus if we store that address, we can refer to it through the pointer variable.

C++, which evolved from C, can also use pointers as references, but it also supports references in their own right.

The key difference is that pointers have an identity of their own, references do not. The address of a reference is always the object being referred to. After all; it is just an alternate name for that object. Conversely, the address of a pointer is the identity of the pointer, not the value of the pointer (the address being referred to).

References also differ from pointers in that pointers may be null whereas references can never be null. A null pointer is a pointer that holds no address (is assigned the value zero) and therefore points at nothing in particular. Thus when passing objects to functions that expect a valid object, pass a reference. If the object is an optional argument, pass a pointer.

Pointers must also be tested to ensure they are non-null before attempting to access the memory being pointed at. Dereferencing a null pointer has undefined behaviour.

Answer 4

"A reference in Java Script affectively means a variable data type whose value takes the form of an address. A variable in Java Script is a terms that is used for an item of data that is named by an identifier. Each of these variables has a type which it can be classified under, such as 'int' or 'Object' and a scope. Commonly, in Java, variable have to be one of two types: 'Primitive' type or 'reference' type, and cannot be both. This statement leads to major simplifications within the syntax involved in certain expressions that are relative to C++. This provides a vast amount of flexibility for programmers using Java Script, but can lead to errors that are undetectable when compiling, and are only shown to exist when the writtenprogram is actually running.

A reference variable in Java contains an address, or a reference to an address (similar to pointer variables in C++). Java does not, however, allow this address to be arbitrarily (randomly) edited or changed in any way. This goes for pointer variables in C++ as well. So, reference variables are similar to pointer variables in C++. They provide a method through which to access another variable or memory address that has a variable, and allow changes to the data within the afore-mentioned memory address. A reference variable provides direct access to this memory address.

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Answer 5

It is meaningless because a reference is not a variable of any kind. A reference is simply an alias for an already existing object and, once assigned, cannot be reassigned to another object. Although a reference is not variable, the object it refers to can be.

Note that a reference is not the same as a pointer, although they share some similar properties. A pointer is a variable that stores the address of an object and allows the object to be accessed through indirection (dereferencing). However, pointers can be reassigned and may be NULL while references cannot. References are easier to work with, but pointers are more flexible.

Answer 6

By assigning an object (or reference) to them at the point of instantiation.

Answer 7

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