about constructor

[Nilesh Shekokar]

what is the rule for the access specifier for the constructor?
eg if class has public specifier then does this imply that all the construtors of the class are also public.And if yes can we change it?

[vignesh hariharan]

no.. the class scope is different and the constructor scope is different.. even if u have a public class.. u can name ur constructor private..

class test  // default scope for the class defn.
{
  private test() // private constructor. no return type for constructor.
  {
     System.out.println("private constructor");
  }
 
  public static void mtd()
  {
     new test();
  }
}
 
class test1
{
   public static void main(String ar[])
   {
      test.mtd();
   }
}

[Sandeep Vaid]

Class Access Specifier has nothing to do with Constructor Access Specifier.

Example :

 
public class Temp
{
  int i;
  private Temp()
  {
i=10;
  }
}
 
class Temp1
{
  Temp t = new Temp();
}
 

In the above example access specifier for class Temp is public but it's constructor is private. Even by default constructor will get the default specifier (which doesn't depends on class's specifier)

[Marino Christe]

hey if u have a class with default access and if u dont provide any constructor, then the automatically created constructor has the same accees as the class, i.e., default. but if u write ur own constructor, u can write it wid any other access specifier also.

[wise owen]

Check All Possible Combinations of Features and Modifiers.

[Girish Nagaraj]

1)If you explicitly define any constructor for the class then the accessability modifier of the defined constructor(or constructors) is completely independent of the accessability modifier of the class.

2)If you want the compiler to generate a constructor for you(ie you are not defining even a single constructor)then the accessability modifier of the generated constructor is dependent on the accessability modifier of the class.

3)Access mode of the generated constructor is public for public classes, and default for classes with any other access mode.

Hope It is clear.
Let me know If I am wrong.

[Keith Lynn]

Access mode of the generated constructor is public for public classes, and default for classes with any other access mode.

Actually according to the Java Language Specification, the access modifier of the default constructor is the same as the access modifier of the class.

[Aniket Patil]

Hi Sandeep,

Class Temp1 will not be able to create an object of class Temp, as the constructor of Temp is private. In fact, class Temp1 should not be able to even "see" a constructor of Temp, since it is marked private.

Only the members of Temp would now able to create an instance of Temp.

[Girish Nagaraj]

Hi Keith,

I think we have to Check out for inner classes.

Bcoz inner classes can have all(public, protected, default/package, private)access modifiers.

[Keith Lynn]

Originally posted by Girish Nagaraj:
Hi Keith,

I think we have to Check out for inner classes.

Bcoz inner classes can have all(public, protected, default/package, private)access modifiers.

This is the link to what the Java Language Specification says.

http://java.sun.com/docs/books/jls/second_edition/html/classes.doc.html#16823

[Girish Nagaraj]

Hi keith,

I checked out for inner classes with diff. modifiers.
What you said was right.
I have modified my points accordingly, Let me know if their is any mistake.

1)If you explicitly define any constructor for the class then the accessability modifier of the defined constructor(or constructors) is completely independent of the accessability modifier of the class.

2)If you want the compiler to generate a constructor for you(ie you are not defining even a single constructor)then the accessability modifier of the generated constructor is dependent on the accessability modifier of the class.

3)The access modifier of the generated constructor is the same as the access modifier of the class.

Hope It is clear.
Let me know If I am wrong.