How to create a Java generic method, similar to a C++ template method?

**Sharmeen** · October 18th, 2012, 01:10 AM

Hi all,
I'm new to Java and I used to program in C++. Now I know that there is a way in C++ to use the templates to create generic methods that can take different types of variable as input. Is this applicable in Java??
I have written this method:

 static boolean inject1=true;
	  public static boolean check_equality(int v11, int v21){
		  if(v11==v21)
			  if(inject1){
				  inject1=false;
				  return false;
				  }
				  else 
			  return true;
		 if(inject1)
			 return true;
 
		return false;
 
	  }

Now I want this method to take int, double and float for example as inputs.
Any suggestions are appreciated.

**helloworld922** · October 18th, 2012, 01:58 AM

Suggested reading: Generic Methods in Java

Java generics can't be primitive types (int, float, double, etc.), but luckily Java has auto-boxing. You can somewhat restrict the type you can pass in by using extends for the generic type:

public static <T extends Number> boolean check_equality(T v11, T v21)

However, there are a few caveats:

1. I could call check_equality with any class which extends Number, such as: check_equality(Float, Integer) or check_equality(BigInteger, Long).

2. Because you are now dealing with objects you should use the .equals() method instead of the == operator.

The alternative is if you want to only allow check_equality(int, int), check_equality(float, float), and check_equality(double, double) (or any other combination) is to copy/paste the function and change the parameter types.

**Sharmeen** · October 18th, 2012, 02:01 AM

This is really appreciated. I will give it a try and will let you know about the results.
Thanks.

**Sharmeen** · October 18th, 2012, 02:33 AM

I think I will go to the traditional way by Copy/paste the method as I only need to check the equality of integers and doubles.
Thanx

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