Constructor

A constructor is a function that initializes a newly allocated object.

Related concepts:  ClassObjectMethod

Closest Wikipedia entry:  Constructor (object-oriented programming) — In class-based, object-oriented programming, a constructor (abbreviation: ctor) is a special type of function called to create an object. It prepares the new object for use, often accepting arguments that the constructor uses to set required member variables. A constructor resembles an instance method, but it differs from a method in that it has no explicit return type, it is not implicitly inherited and it usually has different rules for scope modifiers.

Misconceptions about Constructor

18 documented Misconceptions

AllClassesHaveDefaultConstructor

All classes automatically get a no-argument constructor

CannotChainMemberToConstructor

Method calls or field accesses cannot be chained to a constructor invocation

ConstructorAllocates

The constructor allocates the object

ConstructorParameterIsField

Formal constructor parameters are equivalent to instance variables

ConstructorReturnsObject

Constructors need to return objects

ConstructorWithoutNew

One can write the constructor name, without new, to instantiate a class

ImmutableRequiresFinalParameters

Immutable classes need final constructor/method parameters

MustInitializeFieldInConstructor

Constructors must assign values to all fields

NoEmptyConstructor

A constructor must do something

NoInsideMethodCallInConstructor

It is foirbidden to call other methods on the same object while inside its constructor

ObjectLabeledWithConstructorSignature

In stack and heap diagrams, an object on the heap is labeled like a stack frame of a constructor call

ObjectsMustBeNamed

A variable is needed to instantiate an object

ThisInConstructorIsNull

In a constructor, this is null