A final is a
keyword used for three purposes. They
are
a) final as
constant: A variable can be declared as constant with the keyword
final. It must be initialized while
declaring. One we initialized the
variable with final keyword it cannot be modified in the program. This is similar to the const in C/C++.
Example: final int x = 10;
x = 45
//error
b) final to
prevent overriding: A method that is declared as final cannot be overridden
in a subclass method. It the methods
that are declared as private are implicitly final.
Example: class A
{
final
void show( )
{
System.out.println(“Hello”);
}
}
class B
extends A
{
void
show( )
{ //error
System.out.println(“Hai”);
}
}
c) final to
prevent inheritance: The class that is declared as final implicitly
declares all of its methods as final.
The class cannot be extended to its subclass.
Example: final class A
{
void
show( )
{
System.out.println(“Hello”);
}
}
class B
extends A //error
{
void
show( )
{
System.out.println(“Hai”);
}
}
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