How do I Implement Operators in a Java Class

Question

I am attempting to create a unsigned integer class.

public class UnsignedInteger extends Number implements Comparable<UnsignedInteger> 
    { 
    ... 
    }

Is there a way to implement operators such as; +, -, *, /, <<, >>, |, ^, >>>, <<

I guess i was missing the forest while looking at the trees. — Jay Tomten, Feb 12 '13 at 14:43

score 21 · Accepted Answer · edited May 23 '17 at 12:09

21

Java does not support Operator Overloading. The only option you have is define methods like add(), subtract(), multiply(), etc, and write the logic there, and invoke them for particular operation.

You can have a look at BigInteger class to get an idea of how you can define methods to support various operations. And if interested, you can even go through the source code, that you can find in the src folder of your jdk home directory.

edited May 23 '17 at 12:09

Community

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answered Feb 12 '13 at 14:16

Rohit Jain

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This is a good answer, I think that some explanation on _why_ operator overloading was discluded from the language would add a lot to it :) – Benjamin Gruenbaum Feb 12 '13 at 14:35
@BenjaminGruenbaum. I have added a link to another post on SO, which describes that. – Rohit Jain Feb 12 '13 at 14:40

score 9 · Answer 2 · answered Feb 12 '13 at 14:28

There are already 5 answers saying that you cannot overload operators, but I want to point out that you can not use arithmetical operators on objects at all. They only work with primitive types (int, double, etc).

The only reason the following code compiles

Integer a = 1, b = 2;
Integer c = a + b;

is because the Java compiler compiles it as

Integer a = Integer.valueOf(1), b = Integer.valueOf(2);
Integer c = Integer.valueOf(a.intValue() + b.intValue());

If you want this to work for your UnsignedInteger, you have to extend the javac (it is possible, though).

I give a like for the funny ending. That is a good programmer´s joke. Oh java does have String operations — , Nov 15 '19 at 16:46

score 4 · Answer 3 · answered Feb 12 '13 at 14:15

4

No you cannot override operators in Java.

answered Feb 12 '13 at 14:15

talnicolas

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score 4 · Answer 4 · answered Feb 12 '13 at 14:17

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It's not possible to override operators in Java. What you can do is define methods to represent the operations, like BigDecimal or BigInteger in the standard library do.

answered Feb 12 '13 at 14:17

Cyrille Ka

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DisplayName · Answer 5 · 2016-03-18T02:53:17.777

There is a javac-plugin (an annotation processor like Lombok) called "Java-OO", which adds operator overloading to Java.

It allows you to add operator overloading to your own classes very easily. In addition to this, many of the built-in classes of the Java API also supports operator overloading when using this plugin. (For example: Instead of list.get(6) or map.get("hello") you can do list[6] and map["hello"])

All you need to do is to include the .jar on the classpath when compiling with javac.

There are plugins for all major IDEs: Eclipse, Netbeans and IntelliJ IDEA.

score 2 · Answer 6 · answered Feb 12 '13 at 14:16

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No. Java does not support operator overloading.

answered Feb 12 '13 at 14:16

score 2 · Answer 7 · answered Feb 12 '13 at 14:18

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Java doesnt support operator overloading, they consider it a bad practice, knowing that they overloaded + and += operators for the String class

answered Feb 12 '13 at 14:18

Sleiman Jneidi

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That's only half true. It's syntactic sugar for strings and converted into `StringBuilder#append()` calls by the javac. – Cephalopod Feb 12 '13 at 14:24

How do I Implement Operators in a Java Class

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