encapsulation question

[auvrm papu]

My friend asked me this question to resolve..
can anyone help finding the answer with the reason

 
Which of the following demonstrate encapsulation?
1)
private class Adder
{
private int a;
private int b;
private Adder(int a, int b)
{
this.a = a;
this.b = b;
}
private int sum()
{
return a + b;
}
}



2)
public class Adder
{
private int a;
private int b;
public Adder(int a, int b)
{
this.a = a;
this.b = b;
}
public int sum()
{
return a + b;
}
}


3)

public class Adder
{
public int a;
public int b;
public int sum()
{
return a + b;
}
}


4)

public class Adder
{
protected int a;
protected int b;
protected Adder(int a, int b)
{
this.a = a;
this.b = b;
}
public int sum()
{
return a + b;
}
}
   

[Jeanne Boyarsky]

What do you think? Are there any you can rule out? Maybe they don't compile? Or show poor encapsulation? Have you looked up the definition of encapsulation yet?

[auvrm papu]

i thought it would be choice 2, but not sure

[Vijitha Kumara]

auvrm papu wrote:i thought it would be choice 2, but not sure

First try compiling them and see as Jeanne suggested.

[Rajeev Trikha]

Edited to remove answer.

[David Newton]

Please see DoYourOwnHomework.

And others, please *allow* people to do their own homework.

[Siddhesh Deodhar]

Second one is the best example for encapsulation.

[David Newton]