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From: Martin Gregorie <martin@address-in-sig.invalid>
Newsgroups: comp.lang.java.programmer
Subject: Re: How to assign an object to another in it method?
Date: Mon, 3 Jul 2017 10:59:12 -0000 (UTC)
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On Sun, 02 Jul 2017 21:23:26 -0400, Arne Vajhøj wrote:

> On 6/28/2017 8:51 AM, Eric Douglas wrote:
>> On Wednesday, June 28, 2017 at 8:24:54 AM UTC-4, Andreas Leitgeb wrote:
>>> Obviously, stuff shouldn't be exactly duplicated in multiple c'tor
>>> bodies, and doesn't need to, either, for reasons stated.
>> 
>> public class MyClass String var1;
>> public MyClass(){
>> this("init");
>> }
>> public MyClass(final String arg){
>> var1=arg;
>> }
>> 
>> 
>> Normally it's like this.  Now if you were to put something in the no
>> arg constructor and something calls this one arg constructor with a
>> super(), that gets missed.  I can't think of a case where you would
>> want 2 constructors doing something totally different that shouldn't
>> actually be 2 different classes. >
> 
> The above is one reason - which is really the issue of Java formal
> parameters not supporting default values.
> 
> But there are other reasons. One that comes to my mind is different
> input types carrying the same information.
> 
> String(String original)
> String(char[] value)
> String(byte[] bytes, String charsetName)
> etc.
> 
> comes to mind.
> 
> Of course those are also tightly related.
> 
> Arne


In practise, I often find myself doing something like this:

public class Demo
{
   private String  name;
   private int     number;
   private boolean prisoner;

   public Demo(String name, int answer, boolean prisoner)
   {
      this.name = name;
      this.number = number;
      this.isPrisoner = prisoner;
   }

   public Demo(String name)
   {
      super(name, 6, true);
   }
}

... and so on. 

IOW there's one constructor that can set all attributes that might be set 
externally and a number of others that accept fewer arguments and set 
appropriate defaults for the other attributes.


     
-- 
martin@   | Martin Gregorie
gregorie. | Essex, UK
org       |