posted March 14, 2000 05:03 PM            

Can a constructor be declared private ?
a.)yes
b.)No

Can anyone expalin with an example.

My question is from the point of view of exam.

posted March 16, 2000 02:56 AM            

quote:

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Originally posted by Howard Stern:
The answer is "yes". If you want any to prevent any class from being instantiated you should declare its constructor as private. Hence its constructor shall be applicable only within the class itself and not from any other class. This may apply to any class. Hope this makes it clear.

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Actually it is possible to instantiate classes with only private constructors.Making constructors private only limit the way in
which we can create an instance of the class.An example

class A
{
private A()
{
System.out.println("class A instantiated");
}
public static A instantiate()
{
return new A();
}
}

class B
{
public static void main(String agrs[])
{
A a = A.instantiate();
}
}

posted March 16, 2000 02:33 PM            

code:

---

class A
{
static int count;
private A()
{
System.out.println("class A instantiated");
count++;
}
public static A instantiate()
{
    if (count==0)
        return new A();
    else
        System.out.println("no more A instantiated");        
        return null;
}
}
class B
{
public static void main(String agrs[])
{
A a = A.instantiate();
A b = A.instantiate();
A c = A.instantiate();
System.out.println("A instantiated: " + A.count);        
}
}

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