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

Assignment copies the object

BoxedNull

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

EqualityOperatorComparesObjectsValues

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

EqualsComparesReferences

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

FinalReferenceImpliesImmutability

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

MultiReferenceVariable

A reference variable can point to multiple objects

NullIsObject

null is an object

ReferenceIntoStack

References can point into the stack

ReferenceLabeledWithDynamicType

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

ReferenceToBooleanCoercion

Every reference type can be coerced to boolean

ReferenceToIntegerConversion

One can cast between references and ints

ReferenceToVariable

References can point to variables

SubtypeCompatibleWithSupertype

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

SupertypeIncompatibleWithSubtype

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

ThisAsField

this is a special field in the object

ThisAssignable

One can assign to this

ThisCanBeNull

this can be null

ThisExistsInStaticMethod

this is a local variable, also in static methods

ThisInConstructorIsNull

In a constructor, this is null

VariablesHoldObjects

A variable of a reference type contains a whole object