How to declare variable as per user choice?

Question

So, I was writing a Java program and made a method create that accepted Object datatype variable. Here is the brief look

class FILO
{
   ArrayList listFILO;
   public void create(Object input)
   {
      Class<? extends Object> type=input.getClass();
      if(type.isArray())
      {
        /*Problem starts here. I want to create an array with same datatype as
         input but I can't get my head around it.*/
       }
         //...
    }
}

I think generics might solve your problem, but maybe you are after something different here? — Jamie
– Jamie, Commented Jan 7, 2021 at 17:27
When posting here, learn to use code formatting. Another user fixed some of your post this time. You should still fix the indenting. — Basil Bourque
– Basil Bourque, Commented Jan 7, 2021 at 21:49
@BasilBourque (yep it made my eyes feel bad) -- l'd let him polish the format — aran
– aran, Commented Jan 7, 2021 at 21:54

Basil Bourque · Accepted Answer · 2021-01-07 21:58:51Z

1

You could use reflection, using java.lang.reflect.Array.

Array.newInstance( input.getClass(), length );

But trying to use reflection like this is usually a bad idea. You want to require the user to enter the type you are asking for, and then check that the user has entered the correct type.

edited Jan 7, 2021 at 21:58

Basil Bourque

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answered Jan 7, 2021 at 17:21

markspace

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1 Comment

Abhijit Singh Over a year ago

This program may cause a lot of errors, and I had to create it as I needed a variable which followed First In Last Out. So I decided to create a class which would I then use to create a custom variable with the functions I need. If anyone has any other suggestions how to deal, then please do tell me. And sorry for the code, as I didn't had my computer and wrote the question on my phone

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