Question { Wipro, 20505 }

Can a class inherit the constructors of its superclass?

Answer

Inheriting will inherits the constructor as well.

// This program uses inheritance to extend Box.
class Box {
double width;
double height;
double depth;
// construct clone of an object
Box(Box ob) { // pass object to constructor
width = ob.width;
height = ob.height;
depth = ob.depth;
}
// constructor used when all dimensions specified
Box(double w, double h, double d) {
width = w;
height = h;
depth = d;
}
// constructor used when no dimensions specified
Box() {
width = -1; // use -1 to indicate
height = -1; // an uninitialized
depth = -1; // box
}
// constructor used when cube is created
Box(double len) {
width = height = depth = len;
}
// compute and return volume
double volume() {
return width * height * depth;
}
}
// Here, Box is extended to include weight.
class BoxWeight extends Box {
double weight; // weight of box
// constructor for BoxWeight
BoxWeight(double w, double h, double d, double m) {
width = w;
height = h;
depth = d;
weight = m;
}
}
class DemoBoxWeight {
public static void main(String args[]) {
BoxWeight mybox1 = new BoxWeight(10, 20, 15, 34.3);
BoxWeight mybox2 = new BoxWeight(2, 3, 4, 0.076);
double vol;
vol = mybox1.volume();
System.out.println("Volume of mybox1 is " + vol);
System.out.println("Weight of mybox1 is " + mybox1.weight);
System.out.println();
vol = mybox2.volume();
System.out.println("Volume of mybox2 is " + vol);
System.out.println("Weight of mybox2 is " + mybox2.weight);
}
}

The output from this program is shown here:
Volume of mybox1 is 3000.0
Weight of mybox1 is 34.3
Volume of mybox2 is 24.0
Weight of mybox2 is 0.076

BoxWeight inherits all of the characteristics of Box and
adds to them the weight
component. It is not necessary for BoxWeight to re-create
all of the features found in
Box. It can simply extend Box to meet its own purposes

Question { Magna Infotech, 21353 }

Is form beans are serializable or not?

Answer

because if you want send to status of variable over the
network you need to searializable the class

Question { Infosys, 24312 }

what is the difference between Cpp And Java

Answer

Buddy,
Java is not 100% object oriented because of the
primary data types. But we will do wrapping to convert
these to classes.

Question { Innodata Isogen, 15507 }

how to call One constructor from another;

Answer

This.constructername() keyword can be used with in the
class to refer. To use super class constructer we need to
give super.consturctername().

Question { IBM, 7116 }

we have two threads..both the threads are reading the
data.. is there any need of synchronization
there?...justify it?

Answer

In this case synchronization is not requied because u r not
going to change the data.
U can use synchronization but performence will decrease.