Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people, just like you, are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
Solved

how to override operator in java?

Posted on 2001-08-01
9
6,909 Views
Last Modified: 2008-01-09
hi, I'm a C++ program and new in Java, how can I override the operators (==,+=,=,-= etc) in Java ? For example in c++ we do :

Class Test
{
   int value;
   Test()
   {
     value= 0;
   };
   
  const Test& operator =(Test t)
  {
    this->value = t.value;
  }
  bool operator ==(Test t)
  {
    return this->value == t.value;
  }
}

how to do this in Java?
0
Comment
Question by:eugeneng
  • 3
  • 2
  • 2
  • +2
9 Comments
 
LVL 1

Accepted Solution

by:
LDC earned 30 total points
ID: 6343535
You cannot overload operators in java.
The = operator is useless anyway because it is always pointers/references that you handle.
The == should not be used, but the method equals() should be. (== tests whether the "pointers" are the same).
0
 
LVL 5

Expert Comment

by:LexZEUS
ID: 6343641
use equals() to compare 2 objects, or maybe hashCode() ...

For easier apporach, 2 objects are same if :
1. Have same parent class / interface
2. The hashCode() are same
0
 
LVL 7

Expert Comment

by:tomboshell
ID: 6343716
If you need a function that 'acts' like an overloaded operator than it would be best to write your own.  You did in the example.  You can override many functions, creating your own implementation if needed.  Or write a similar function.  Many programmers write their own utilties libraries of functions they need.  

Tom
0
Free Tool: Subnet Calculator

The subnet calculator helps you design networks by taking an IP address and network mask and returning information such as network, broadcast address, and host range.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

 
LVL 1

Expert Comment

by:LDC
ID: 6344221
LexZEUS, 2 objects are not necessarily the same if the hasCode() is the same, even for a given class. The only specification in hashCode is that it returns the same number for equal objects, not that it return different numbers for different objects.
0
 

Author Comment

by:eugeneng
ID: 6346978
so is operator overriding "achievable" in java or not ?
0
 
LVL 5

Expert Comment

by:gbentley
ID: 6347100
The simple answer is no. Java does not support operator overloading. It is by design. It does mean a different sty

Regards
Gordon
0
 
LVL 5

Expert Comment

by:gbentley
ID: 6347101
The simple answer is no. Java does not support operator overloading. It is by design. It does mean a different style of object design is needed.

Regards
Gordon
0
 
LVL 5

Expert Comment

by:gbentley
ID: 6347102
Sorry about the double message!
0
 
LVL 5

Expert Comment

by:LexZEUS
ID: 6347142
>LexZEUS, 2 objects are not necessarily the same if the hasCode() is the same, even for a given class.
The only specification in hashCode is that it returns the same number for equal objects, not that it return different numbers for different objects.

Yes... I just said the previous comment for a basic implementation of using equals() method for generic Class ...

0

Featured Post

Free Tool: Site Down Detector

Helpful to verify reports of your own downtime, or to double check a downed website you are trying to access.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
Java string replace 11 54
How to convert from xls to xlsx using java 7 55
Html Table Looping (part 2) 5 27
Eclipse for Java EE development 2 27
An old method to applying the Singleton pattern in your Java code is to check if a static instance, defined in the same class that needs to be instantiated once and only once, is null and then create a new instance; otherwise, the pre-existing insta…
Are you developing a Java application and want to create Excel Spreadsheets? You have come to the right place, this article will describe how you can create Excel Spreadsheets from a Java Application. For the purposes of this article, I will be u…
Viewers learn about the “while” loop and how to utilize it correctly in Java. Additionally, viewers begin exploring how to include conditional statements within a while loop and avoid an endless loop. Define While Loop: Basic Example: Explanatio…
Viewers will learn about the regular for loop in Java and how to use it. Definition: Break the for loop down into 3 parts: Syntax when using for loops: Example using a for loop:

839 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question