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

  1. #1
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    Default How to create a Java generic method, similar to a C++ template method?

    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.


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

    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.

  3. The Following User Says Thank You to helloworld922 For This Useful Post:

    Sharmeen (October 18th, 2012)

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

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

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

    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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