473,396 Members | 1,797 Online
Bytes | Software Development & Data Engineering Community
Post Job

Home Posts Topics Members FAQ

Join Bytes to post your question to a community of 473,396 software developers and data experts.

why hasCode in java ????

dmjpro
2,476 2GB
a method with public int hasCode() provided by Object class .... what is the significance of it .....

plz help me out ... thanxxxx
Mar 12 '07 #1
3 5634
r035198x
13,262 8TB
a method with public int hasCode() provided by Object class .... what is the significance of it .....

plz help me out ... thanxxxx
It is called hashCode and is used for storage in collections. Every object must have a unique hash code for efficient implementation of storage and retrieving from collections.
Mar 12 '07 #2
dmjpro
2,476 2GB
a new think i came to know ...... plz tell me some tips to override the hasCode method to increase the performance while it is used in cellection frameworks ....

any help is most welcome .... thanx
Mar 12 '07 #3
r035198x
13,262 8TB
a new think i came to know ...... plz tell me some tips to override the hasCode method to increase the performance while it is used in cellection frameworks ....

any help is most welcome .... thanx
Here is the contract, copied from the java.lang.Object specification:




"Whenever it is invoked on the same object more than once during an execution of an application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application.





If two objects are equal according to the equals(Object) method, then calling the hashCode method on each of the two objects must produce the same integer result.



It is not required that if two objects are unequal according to the equals(Object) method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hash tables."
Mar 12 '07 #4

Sign in to post your reply or Sign up for a free account.

Similar topics

2
by: Michael | last post by:
Hello I am trying to write a Java-Program which converts a XML-file in a HTML. It should take the Transformation-file from the XML-file itself. Below find a possible XML-file: <?xml...
0
by: Ravi Tallury | last post by:
Hi We are having issues with our application, certain portions of it stop responding while the rest of the application is fine. I am attaching the Java Core dump. If someone can let me know what...
1
by: ptaz | last post by:
Hi I'm trying to run a web page but I get the following error. Ca anyone please tell me a solution to this. Thanks Ptaz HTTP Status 500 - type Exception report
11
by: DrUg13 | last post by:
In java, this seems so easy. You need a new object Object test = new Object() gives me exactly what I want. could someone please help me understand the different ways to do the same thing in...
0
by: Markus Wollny | last post by:
Hello! When I try to run ./configure --with-java, it complains that ant doesn't work. However ant is installed, as is the latest Java SDK 1.4.2 from sun, PATH and JAVA_HOME are set correctly; ...
0
by: mailkhurana | last post by:
Hii , I am trying to use a type 2 driver to connect to DB2 0n AIX 5 I have a small java test to class to establish a conneciton with the db .. I am NOT using WAS or any appserver When I try to...
1
by: David Van D | last post by:
Hi there, A few weeks until I begin my journey towards a degree in Computer Science at Canterbury University in New Zealand, Anyway the course tutors are going to be teaching us JAVA wth bluej...
0
oll3i
by: oll3i | last post by:
package library.common; import java.sql.ResultSet; public interface LibraryInterface { public ResultSet getBookByAuthor(String author); public ResultSet getBookByName(String name);
0
by: Charles Arthur | last post by:
How do i turn on java script on a villaon, callus and itel keypad mobile phone
0
by: ryjfgjl | last post by:
In our work, we often receive Excel tables with data in the same format. If we want to analyze these data, it can be difficult to analyze them because the data is spread across multiple Excel files...
0
by: emmanuelkatto | last post by:
Hi All, I am Emmanuel katto from Uganda. I want to ask what challenges you've faced while migrating a website to cloud. Please let me know. Thanks! Emmanuel
0
BarryA
by: BarryA | last post by:
What are the essential steps and strategies outlined in the Data Structures and Algorithms (DSA) roadmap for aspiring data scientists? How can individuals effectively utilize this roadmap to progress...
1
by: nemocccc | last post by:
hello, everyone, I want to develop a software for my android phone for daily needs, any suggestions?
0
marktang
by: marktang | last post by:
ONU (Optical Network Unit) is one of the key components for providing high-speed Internet services. Its primary function is to act as an endpoint device located at the user's premises. However,...
0
by: Hystou | last post by:
Most computers default to English, but sometimes we require a different language, especially when relocating. Forgot to request a specific language before your computer shipped? No problem! You can...
0
Oralloy
by: Oralloy | last post by:
Hello folks, I am unable to find appropriate documentation on the type promotion of bit-fields when using the generalised comparison operator "<=>". The problem is that using the GNU compilers,...
0
by: Hystou | last post by:
Overview: Windows 11 and 10 have less user interface control over operating system update behaviour than previous versions of Windows. In Windows 11 and 10, there is no way to turn off the Windows...

By using Bytes.com and it's services, you agree to our Privacy Policy and Terms of Use.

To disable or enable advertisements and analytics tracking please visit the manage ads & tracking page.