Programming Tutorials Browser Tutorials Articles Struts Tutorials Hibernate Tutorials

Search: 

  Tutorial: Object equality

Object equality Writing equals and hashCode methods for data objects Summary In this article, Alex Blewitt describes the two most common methods in the Java languageâ??equals() and hashCode()â??and shows how they can be implemented correctly. The

Tutorial Details:

very Java object inherits a set of base methods from java.lang.Object that every client can use:

Creational methods
Object()
Default no-argument constructor
clone()
Returns a new instance of the class
Synchronizing methods
notify()F
Sends a signal to a waiting thread (on the current instance)
notifyAll()F
Sends a signal to all waiting threads (on the current instance)
wait()F
Forces the current thread to wait for a signal (on the current instance) Equality methods
equals(Object)
Returns true if this instance is equal to the argument
hashCode()
Returns a hash code based on the instance data
Other methods
toString()
Returns a string representation of the object
finalize()
Performs garbage-collection duties
getClass()F
Returns the Class object associated with the instance


Each of these methods has a sensible default behavior that can be overridden in the subclasses (except for final methods, marked above with F). This article discusses overriding the equals() and hashCode() methods for data objects.


 

Read Tutorial at: Click here to view the tutorial

Rate Tutorial:
Object equality

View Tutorial:
Object equality

Related Tutorials:

Displaying 1 - 50 of about 1595 Related Tutorials.

Equality and Relational Operators
Equality and Relational Operators Equality... of two expressions or operands in a program then the equality and relational..., less than to another operand. There are different types of equality
 
Insert an object with the add(Object) method
Wrapper Class Example, Adding value through add(Object) method Insert an object with the add(Object) method   ...; In this section you will learn to insert an object at the end of a list using the add(Object
 
==, .equals(), and compareTo()
that can be used with object references are comparing for equality...() Java Notes==, .equals(), and compareTo() Equality comparison... Primitives Objects a == b, a != bEqual valuesRefer to the same object. a.equals(b) N
 
Deserializing an Object in java
Deserialization Java,Deserializing Java Object,Deserializing an Object in Java Deserializing an Object in java... how to read any data or contents from the serialized object or file. It takes
 
Convert an Integer type object to a String object
()) method Convert an Integer type object to a String object...; In this section you will learn to convert the Integer type object to a String object using the Integer.toBinaryString() and Integer.toHexString
 
Request Object In JSP
Request Object In JSP Request Object In JSP...;  This section illustrates more about the JSP implicit object called Request object. This object retrieves values whatever client passes
 
Serializing an Object in Java
Java Serialization,Serializing an Object in Java,Serialization in Java Serializing an Object in Java   ...; Introduction Serialization is the process of saving an object in a storage medium
 
Convert Object To String
Convert Object To String Convert Object To String...;  In this section, you will learn to convert an object to a string. Object is a class of java.lang package. Code Description: This program helps
 
getAttribute() Method Of The Request Object
getAttributeMethod() method of the request object getAttribute() Method Of The Request Object   ... object in JSP. This method retrieves the values corresponding to the given
 
removeAttribute() Method Of The Request Object
removeAttribute() method of the request object in JSP removeAttribute() Method Of The Request Object  ...; This section introduces for the method removeAttribute() of the request object
 
Object-Oriented Design - Overview
Java: Object-Oriented Design - Overview Java: Object-Oriented Design - Overview Background... generally accepted best practice is use of object-oriented approaches, using
 
Convert Object to Int
Convert Object to Int,Convert Object to Int in Java,Java Convert Object to Int Convert Object to Int   ..., we are going to learn to convert a numeric string type Object into a primitive
 
Replace an object with set(int, Object) method
Wrapper Class Example, Replace a  value through set(int, Object) method Replace an object with set(int, Object) method...; In this section you will learn to replace an object from a particular
 
Convert Object to Double
Convert Object To Double Convert Object to Double...;  In this section, we are going to convert an object type data... an object type data into a double. An object contains a data 10. Firstly, we
 
Understanding Connection Object
JDBC Connection, Understanding Connection Object Understanding Connection Object     ... object represents a connection with a database. When we connect to a database
 
Associate a value with an object
Associating a value with an object Associate a value with an object        ... to associate value with an object in Java util. Here, you will know how to associate
 
getHeader() Method Of The Request Object
getHeader() method of request object getHeader() Method Of The Request Object      ... you the best illustration about the getHeader() method of the request object. Here
 
Create JTree using an Object
Create Jtree in Java,Creating Tree Using an Object,How to Create Tree Using Object in Java Swing Create JTree using an Object... object that works with Hashtable.  Program Description:   
 
getAttributeNames() Method Of The Request Object
getAttributeNames() method of the request object getAttributeNames() Method Of The Request Object  ...() method of the request object in JSP. Here, you will learn why this is used and how
 
getRequestURI() Method Of The Request Object
getRequestURI() method of the request object getRequestURI() Method Of The Request Object    ... of the request object in JSP. This method is used for getting the information of the URI
 
setAttribute() Method Of The Request Object
setAttribute() method of the request object setAttribute() Method Of The Request Object    ... object in JSP. This method sets the value of the attribute for the request which
 
JavaScript array object reference
JavaScript array object reference JavaScript array object reference        ... a code that helps you in understanding JavaScript array object reference
 
Class, Object and Methods
Class Class, Object and Methods...; Class : Whatever we can see in this world all the things are a object. And all... the properties of the object should be matched with it's own class. Object is the feature
 
Accessing Session Object
Session Object,Session Object in Struts 2,Accessing Session Object in Struts 2 Accessing Session Object    ... object, session context and the last accessed session time. To access the session
 
Java - Class, Object and Methods in Java
Java Class Methods,Java Object Example,Object Methods in Java,The Class and Object Java - Class, Object and Methods in Java... are a object. And all the objects are categorized in a special group. That group is termed
 
The Document Object Model (DOM) APIs
The Document Object Model The Document Object Model...;       The Document Object Model implementation is defined..., returns an object needed to implement the W3C Document interface. The factory
 
Finding out the object of the class
Reflection in java, Inspect the Object name included in the Application...: 10pt; margin: 0px; }--> Finding out the object...;   This section illustrates how to retrieve an object name
 
Convert Object To XML
Convert Object To XML Convert Object To XML...;  Here we are discussing the conversion of an object... into xml file as child node values. Convert Object To XMLTo create a xml file
 
Example to create exception object in java
Example to create exception object in java Example to create exception object in java   ...; the way to create exception object and also to use this object appropriately
 
Java example program to get the object's ID
java example program to get the object's ID Java example program to get the object's ID    ...;         java get Object id
 
Java example to get Object class name at runtime
java example to get Object class name at runtime Java example to get Object class name at runtime   ... Object class name In java there is a way that makes us enabled to get the object
 
To Retrieve a Particular Object From an ArrayList
Wrapper Class Example, To retrieve the ArrayList object that contains all elements in the array To Retrieve a Particular Object From... an ArrayList object (that contains multiple elements) using the get() method. Here
 
Photoshop Tutorial : How to remove an object from a picture
Photoshop : remove an object from a picture How to remove an object from a picture      ... to remove an object from a picture. If you want to remove an object, which you
 
Html tag inside out implicit object
How to use a Html tag inside out implicit object Html tag inside out implicit object   ...; In this program we are going to use a html tag inside a out object. out object is used
 
Access Static Member Of The Class Through Object
Access Static Member Of The Class Through Object Access Static Member Of The Class Through Object   ... are special type of methods that work without any object of the class. Static
 
Insert an element with the add(int, Object) method
Wrapper Class Example,Adding value through add(int, Object) method Insert an element with the add(int, Object) method... using the add(int, Object) method. Here is an example that provides the usage
 
Object-Oriented Programming
Java: Object-Oriented Programming Java: Object-Oriented Programming Beyond OOP Here's an interesting article about going beyond OOP: The Next Move in Programming: A Conversation
 
Object-Oriented Design - Overview
Java: Object-Oriented Design - Overview Java: Object-Oriented Design - Overview Encapsulation Article GetterEradicator It's a nice article about Encapsulation by Martin Fowler
 
Java as an Object Oriented Language
Introduction Java as an Object Oriented Language.... OOP stands for Object Oriented Programming. This is a technique used.... In OOPs, every real life object has properties and behavior. which is achieved
 
Prepared Statement Set Object
JDBC SetObject,Prepared Statement Example,Prepared Statement Set Object... PreparedStatement object as it reduces the execution time. PreparedStatement object is faster than the Statement object as it is precompiled. 
 
getHeaderNames() Method Of The Request Object
getHeaderNames() method of the request object getHeaderNames() Method Of The Request Object   ... of the request object that is used for getting the name of all the header names existed
 
Uses Of Chunk Object
Uses Of Chunk Object Uses Of Chunk Object            ...;The Chunk object");     Document 
 
Writing Java Object (POJO)
Hibernate Mapping,Hibernate PoJO,Writing Java Object (POJO) Writing Java Object (POJO)     ... class and the hibernate mapping file to map the login object to the database table
 
String Comparison
for equality, don't use ==. The == operator checks to see if two objects are exactly the same object. Two strings may be different objects, but have the same... to compare strings for equality. Similarly, use the .compareTo() method to test
 
Master Java In A Week
as a programming language Java is an Object oriented application... as an Object Oriented Language In this section, we will discuss the OOPs... for the application in object format resides on the user's machine
 
Java & JEE books Page3
, object-oriented scripting language. JavaScript is a small, lightweight language... a browser (Navigator or another web browser) and its Document Object Model (DOM...-platform, object-based scripting language for client and server applications
 
JDO UNPLUGGED - PART 1
JDO - Java Data Objects Tutorials, JDO Java Data Object, JDO Tutorial, JDO...;      Java Data Objects is an 'Object... Hibernate from SourceForge, Object Relational Bridge(OJB) from Apache, Toplink from
 
OOP Tutorial [first draft]
implementation of Comparable. 1. Introduction Object-Oriented Design (OOD) and Object-Oriented Programming (OOP) An important part of Object... process. In contrast to this, Object-Oriented Programming is concerned
 
Exceptional Example in Java
an object of the Exception method. On making an object of exception method, java send it to the program by throwing the object of exception method. The Exception Object states the information of type of error and status of program during
 
Constructors
NotesConstructors When you create a new instance (a new object) of a class... are used to initialize the instance variables (fields) of an object. Constructors... for object references, and false for booleans). Default constructor
 
Site navigation
 

 

Send your comments, Suggestions or Queries regarding this site at roseindia_net@yahoo.com.

Copyright © 2006. All rights reserved.