Why do we declare the variables private in a bean

Question

Hi,
when we create a bean in the MVC architecture why do we declare the variables private. Also when do we use the access specifier private.
Regards,
Prashant

Answer 1

pksingh79 wrote:
Hi ^^,
thanks for replying.I had a discussion with one of my trainers and he was of the opinion that the variables should generally be declared private. In this way we prevent classes from accessing and setting illegal values to those variables.
Say for instance we have the class person as follows:
public class Person
int age;
setAge(int age)
if (age < 0)
return null
Person p = new Person() ;
p.age = -2;
//this would be perfectly legal
//where as if we declare the variable as private as follows:
public class Person
private int age;
setAge(int age)
if (age < 0)
return null
Person p = new Person() ;
// P.age = -2;   this would be illegal as age is private and would have to be accessed by the method defined above.
p.setAge(-2);
//the cbove line would retun null values.
public class Person {
    private int age;
    public void setAge(int age) {
        if (age < 0) {
            throw new IllegalArgumentException("...");
        this.age = age;
}