[PDF] Polymorphism in Java PDF Polymorphism.pdf

Since method invocation is determined by the JVM not compiler, it is known as runtime polymorphism class Bike{ void run(){System out println("running");} }

The parameter list that differentiates one method from another is said to be the method signature list There is another form of polymorphism called late-binding (or run-time) polymorphism because the computer does not know at compile time which of the methods are to be executed

[PDF] Polymorphism

Even though our objects were of compile- time type Object, the equals method of the CheckingAccount class was called ○ This occurs because Java chooses

[PDF] Object & Polymorphism - Rose-Hulman

Polymorphism Check out Polymorphism from SVN Every class in Java inherits from Object ▻ Directly and Compile-time error if try to use method not in A

[PDF] Run Time Polymorphism Against Virtual Function in Object Oriented

compiler In this paper, we will discuss the role of Run Time Polymorphism and how it can be similar results (for example, returning values of the same type)

[PDF] Polymorphism - BVRIT Hyderabad

Method Overriding in Java – This is an example of runtime time (or dynamic polymorphism) 3 Types of Polymorphism – Runtime and compile time – This is our

[PDF] Polymorphism in Java

Since method invocation is determined by the JVM not compiler, it is known as runtime polymorphism class Bike{ void run(){System out println("running");} }

[PDF] Polymorphism in Java - Pragjyotish College

There are two types of polymorphism in Java: compile-time polymorphism and runtime polymorphism We can perform polymorphism in java by method

[PDF] COMPILE TIME AND RUNTIME

Compile Time and Runtime Page 2 Example Consider this Java assignment statement: x = y2 + z; To determine if it is correct, the compiler needs to know if y2

[PDF] Polymorphism means many - Chapter &#, Title

Polymorphism in Java ﺗﻌددﯾﺔ اﻷﺷﮐﺎل ﻓﻲ Polymorphism means many (poly) shapes (morph) ❖Compile Time Polymorphism or static binding or early binding

[PDF] compiler explorer

[PDF] complete english grammar books free download pdf

[PDF] complete list of linux commands pdf

[PDF] complete spoken english course pdf

[PDF] completez avec etre ou avoir

[PDF] complex exponential fourier series calculator

[PDF] complex exponential fourier series in matlab

[PDF] complex fft matlab

[PDF] compo géo la france en ville

[PDF] composite materials are classified based on

[PDF] composition geo la france en ville

[PDF] comprehensive list of linux commands

[PDF] comprendre le langage corporel du chat

[PDF] comprendre le langage de la queue du chat

[PDF] comprendre le langage des humains

Object & Polymorphism

Check out Polymorphism from SVN

Inheritance, Associations, and

Dependencies

6ROLG OLQH RSHQ MUURROHMG ´OMV-Mµ

Field association lines

are solid

Dependency lines are dashed

Use association lines only when an item

is stored as a field.

Two types of open arrowheads

`Generalization (superclass) `Specialization (subclass) -a Two types: solid line= inherits, dotted line = implements

The superest class in Java

Everyclass in Java inherits from Object

`Directly and explicitly: ŃSXNOLŃ ŃOMVV 6PULQJ H[PHQGV 2NÓHŃP S"` `Directly and implicitly:

Ńclass BankAccountS"`

`Indirectly:

Ńclass SavingsAccountextends BankAccountS"`

Q1 `String toString() `booleanequals(Object otherObject) `Class getClass() `Object clone()

Often overridden

Sometimes useful

Often dangerous!

Q2 `Return a concise, human-readable summary of the object state `9HU\ XVHIXO NHŃMXVH LP·V ŃMOOHG MXPRPMPLŃMOO\

ŃDuring string concatenation

ŃFor printing

ŃIn the debugger

`getClass().getName() OR getClass().getSimpleName() comes in

OMQG\ OHUH"

Q3 `equals(Object foo) ²should return true when comparing two objects of same type

RLPO VMPH ´PHMQLQJµ

`How?

ŃMust check types³use instanceofOR

ŃMust compare state³use cast

Recall casting a variable: Taking an

Object of one particular type and

´PXUQLQJ LP LQPRµ MQRPOHU 2NÓHŃP type

Review and Practice

`A subclass instance is asuperclassinstance

ŃPolymorphism still works!

BankAccountba= new SavingsAccount();

ba.deposit(100); `But not the other way around!

SavingsAccountsa= new BankAccount();

sa.addInterest(); `Why not? BOOM! `If Bextends or implements A, we can write

A x = new B();

Declared type tells which

methods x can access.

Compile-time error if try to

use method not in A.

The actual type tells which

method to use. `Can cast to recovermethods from B: ((B)x).foo()

Now we can access all of

it gives a run-time error (class cast exception) `Step 1: Identify the Declared/Casted Type ŃThis is the item to the left of the variable name when the variable was declared: xBankAccountsa= new SavingsAccount();

ŃDeclared Type may be changed due to a cast:

Ń((SavingsAccount)sa).addInterest();

ŃIf there is a casted type, record that, otherwise use the declared type.

Declared Type

Casted Type

`Step 2: Identify the Instantiation/Actual Type ŃThis is the type on the right hand side of the equal sign the last time the variable was assigned to: xBankAccountsa= new SavingsAccount();

ŃRecord the instantiation type

Instantiation Type

`Step 3: Check for Compilation Errors Calling a method that is not available based on the declared or casted type of the object

BankAccountsa= new SavingsAccount();

sa.addInterest(); Compiler Error: BankAccountdoes not have addInterest

Incompatible type assignment

SavingsAccountx = new BankAccount();

Compiler Error: BankAccountscan not be stored in

SavingAccounttyped variables

HQYMOLG ŃMVP ŃMVPLQJ PR M P\SH POMP LVQ·P LQ POH PUHH NHORR the declaration type.

BankAccountsa= new SavingsAccount();

((SafetyDepositBox)sa).depositItem();

SafetyDepositBoxis not below BankAccount.

Cannot instantiate interfaces or abstract classes! `Step 4: Check for Runtime Errors

Runtime errors are caused by invalid casting.

An item may only be cast to a type IF:

xThe instantiation type matches the casted type xThe casted type is between the declaration type and the instantiation type

BankAccountsa= new SavingsAccount();

((CheckingAccount)sa).deductFees(); Runtime Error: SavingsAccountis not a CheckingAccount

Account a = new CheckingAccount();

((BankAccount)a).deposit(); This is valid because a CheckingAccountis a BankAccount `Step 5: Find Method to Run

ŃFind the instantiation type in the hierarchy.

1.If that type implements the given method, then use

that implementation.

2.Otherwise, move up to the parent type and see if

POHUH·V MQ LPSOHPHQPMPLRQ POHUHB

a.If there is an implementation, use that. b.Otherwise, repeat step 2 until an implementation is found. `Do questions 5 through 7 from Quiz. `Please hand them in when done and then start reading the BallWorlds specification on your schedule page. Q5-7, hand in when done, then start reading BallWorldsspec

Pulsar, Mover, etc.

quotesdbs_dbs20.pdfusesText_26

[PDF] [PDF] Polymorphism in Java

Object & Polymorphism

Check out Polymorphism from SVN

Inheritance, Associations, and

Dependencies

6ROLG OLQH RSHQ MUURROHMG ´OMV-Mµ

Field association lines

Dependency lines are dashed

Use association lines only when an item

Two types of open arrowheads

The superest class in Java

Everyclass in Java inherits from Object

Ńclass BankAccountS"`

Ńclass SavingsAccountextends BankAccountS"`

Often overridden

Sometimes useful

Often dangerous!

ŃDuring string concatenation

ŃFor printing

ŃIn the debugger

OMQG\ OHUH"

RLPO VMPH ´PHMQLQJµ

ŃMust check types³use instanceofOR

ŃMust compare state³use cast

Recall casting a variable: Taking an

Object of one particular type and

´PXUQLQJ LP LQPRµ MQRPOHU 2NÓHŃP type

Review and Practice

ŃPolymorphism still works!

BankAccountba= new SavingsAccount();

SavingsAccountsa= new BankAccount();

A x = new B();

Declared type tells which

Compile-time error if try to

The actual type tells which

Now we can access all of

ŃDeclared Type may be changed due to a cast:

Ń((SavingsAccount)sa).addInterest();

Declared Type

Casted Type

ŃRecord the instantiation type

Instantiation Type

BankAccountsa= new SavingsAccount();

Incompatible type assignment

SavingsAccountx = new BankAccount();

Compiler Error: BankAccountscan not be stored in

SavingAccounttyped variables

BankAccountsa= new SavingsAccount();

SafetyDepositBoxis not below BankAccount.

Runtime errors are caused by invalid casting.

An item may only be cast to a type IF:

BankAccountsa= new SavingsAccount();

Account a = new CheckingAccount();

ŃFind the instantiation type in the hierarchy.

1.If that type implements the given method, then use

2.Otherwise, move up to the parent type and see if

POHUH·V MQ LPSOHPHQPMPLRQ POHUHB

Pulsar, Mover, etc.