Java Object Oriented Programming and Method

  

JAVA

Object Oriented Programming and Method

 

Fill in the blanks

 

1.Abstraction means data hiding

2.Encapsulation means binding and wrapping data into a single unit

3.Inheritance advantage code reuse

4.Polymorphism means one interface, Multiple method or Multitasking

5.Object means Collections of data

6.Class means Collections of Object

7. new is used for address in memory of object is allocated.

8.Write a syntax of method typename(parameter){}

9.Method Overloading means function name same argument different

10.Passing object to a method is called Call by Reference

Answer the Following Questions

                                                                (4 marks)

1.Write a program to find volume of box using class and object by passing one argument.

File name: Box.java

class Box {

       double width;

       double height;

       double depth;

}

//This class declares an object of type Box.

File name: BoxDemo.java

class BoxDemo{

   public static void main(String args[]){

       Box mybox = new Box();

       double vol;

       //assign values to mybox's instance variable

     mybox.width = 10;

     mybox.height = 20;

     mybox.depth = 15;

     //computer volumn of box

    vol=mybox.width * mybox.height * mybox.depth;

    System.out.println("Volumn is"+vol);

}

}

2.Write a program for object Reference

File name: ObjDemo.javaclass 

class ObjDemo

{

  int a;

public static void main(String args[])

{

          ObjDemo o1,o2;

           o1=new ObjDemo();

           o1.a=100;

           o2=new ObjDemo();

           o2.a=100;

   if(o1==o2)

    System.out.println("Both are equal");

     else

       System.out.println("Both are not equal");

     //reference of object o1 is assigned to object o2

o2=o1;

if(o1==o2)

        System.out.println("Both are equal");  

else

          System.out.println("Both are not equal");

  }

}

 

3.Write a program for call by value

In java simple type of method ,it is passed by value is called call by value.

File name: CallTest.java

class CallTest{

      void change(int i)

    {

        i=i+1;

        System.out.println("Inside function i ="+i);

       }

}

File name: CallByValue.java

class CallByValue  {

   public static void main(String args[]){

     CallTest ob=new CallTest();

      int a=10;

      System.out.println("Before call a="+a);

      ob.change(a);

            System.out.println("Before call a="+a);

          }

}

 

4.Write a program for call by reference

File name: RefTest.java

class RefTest{

      int a,b;

      void change(RefTest o){

            o.a+=2;

            o.b-=2;

         }

            void show(){                                        

            System.out.println("A="+a+",B="+b);

           }

}

 File name: CallByRef.java

class CallByRef{

             public static void main(String args[]){

             RefTest ob1=new RefTest();   

             RefTest ob2=new RefTest();

            ob2.a=10;

            ob2.b=20;

            System.out.println("Before calling change");

            ob2.show();

            ob1.change(ob2);

            System.out.println("After calling change");

            ob2.show();

            }

}

 

 

Answer the Following Questions

                                                                (4 marks)

1.Write a class and object program to find volume of box using calling method by passing two argument.

File name: Box.java

class Box {

       double width;

       double height;

       double depth;

//This class declares an object of type Box.

File name: BoxDemo1.java

class BoxDemo1{

   public static void main(String args[]){

       Box mybox1 = new Box();

       Box mybox2 = new Box();

       double vol;

       //assign values to mybox's instance variable

     mybox1.width = 10;

     mybox1.height = 20;

     mybox1.depth = 15;

     mybox2.width = 3;

     mybox2.height = 6;

     mybox2.depth = 9;

     //compute volume  of  1st box

    vol=mybox1.width * mybox1.height * mybox1.depth;

    System.out.println("Volumn is"+vol);

    //compute volume  of  2nd box

    vol=mybox2.width * mybox2.height * mybox2.depth;

    System.out.println("Volume  is"+vol);

}

}

2.Write a program for method overloading.

Two or more methods within the same class method name same ,argument different is called Overloading.

File name: OverloadDemo.java

class OverloadDemo{

     void multi(){

       System.out.println("No values to multiply");

}

     void multi(int a) {

       System.out.println("a*a:"+a*a);

}

      void multi(int a,int b) {

        System.out.println(a+"and"+b+":"+a*b);

}

  double multi(double a){

          return a*a;

}

public static void main(String args[]){

     OverloadDemo ob =new OverloadDemo();

      double result;

     ob.multi();

     ob.multi(10);

     ob.multi(10,20);

     result=ob.multi(123.25);

     System.out.println("Result of ob.multi(123.25):"+result);

}

}