Reference

A reference value points to a sequence of memory locations that may contain an object or array.

Related concepts:  ValueTypeObjectArrayPrimitive

Closest Wikipedia entry:  Reference (computer science) — In computer programming, a reference is a value that enables a program to indirectly access a particular datum, such as a variable's value or a record, in the computer's memory or in some other storage device. The reference is said to refer to the datum, and accessing the datum is called dereferencing the reference. A reference is distinct from the datum itself.

Misconceptions about Reference

29 documented Misconceptions

AssignmentCopiesObject — Java

Assignment copies the object

AssignmentCopiesObject — JavaScript

Assignment copies the object

AssignmentCopiesObject — Python

Assignment copies the object

BoxedNull — Java

Passing null to a wrapper class constructor creates an object representing the absence of a value

ConstReferenceImpliesImmutability — JavaScript

An object referred to by a const variable is an immutable object

EqualityOperatorComparesListIdentities — Scratch

(list a) = (list b) compares the identities of list a and list b

EqualityOperatorComparesObjectsValues — Java

o==p compares the objects referred to by variables o and p

EqualityOperatorComparesObjectsValues — JavaScript

The equality operator compares two objects' values

EqualsComparesReferences — Java

o.equals(p) compares the references stored in the variables o and p

FinalReferenceImpliesImmutability — Java

An object referred to by a final variable is an immutable object

MultiReferenceVariable — Java

A reference variable can point to multiple objects

NullIsObject — Java

null is an object

NullIsObject — JavaScript

null is an object

ObjectAsParameterIsCopied — JavaScript

Objects are passed by value

ReferenceIntoStack — Java

References can point into the stack

ReferenceLabeledWithDynamicType — Java

In stack and heap diagrams, reference variables are labeled with the types of the objects they refer to

ReferenceToBooleanCoercion — Java

Every reference type can be coerced to boolean

ReferenceToIntegerConversion — Java

One can cast between references and ints

ReferenceToVariable — Java

References can point to variables

SubtypeCompatibleWithSupertype — Java

A variable of a subtype can reference an object of a supertype

SupertypeIncompatibleWithSubtype — Java

A variable of a supertype cannot reference an object of a subtype

ThisAsField — Java

this is a special field in the object

ThisAssignable — Java

One can assign to this

ThisAssignable — JavaScript

One can assign to this

ThisCanBeNull — Java

this can be null

ThisExistsInStaticMethod — Java

this is a local variable, also in static methods

ThisInConstructorIsNull — Java

In a constructor, this is null

VariablesHoldObjects — Java

A variable of a reference type contains a whole object

VariablesHoldObjects — Python

A variable contains a whole object