Practical example for Abstraction

[rajaraman navaneethan]

hi friends,
can any one give a practical example of the Abstraction concept in a java program?
i can understand that abstraction means Through the process of abstraction, a programmer hides all but the relevant data aboutan object .
is the following program an example of Abstraction

public class OOP
{
public float cal(float a,float b)
{
return a*b;
}
}
public class XYZ
{
public static void main(String args[])
{
OOP obj=new OOP();
obj.cal(12.3f,10.2f);
}
}

here in the class OOP,the cal method calculates the product of 2 floating point numbers.class XYZ calls the method cal thru the object obj.it does not know the implementation of the cal method,but it gets the o/p.
similarly if we declare a variable int i=10; a 32 bit holder is assisgned to i, which happens behind the scenes.

are the 2 cases above a valid example for abstraction,if not please give a practical example of the concept of abstraction in java

regards,
Raja