Constructor Example 1

class marks

{

        private int mark1,mark2,total;

        marks() {} 

        marks(int m1,int m2)

        {

                mark1 = m1;

                mark2 = m2;

        }

        marks(marks m1)

        {

                mark1 = m1.mark1;

                mark2 = m1.mark2;

        }

        void calc()

        {

                total = mark1 + mark2;

        }

        void putdetails()

        {

                System.out.println("Mark1 : " + mark1);

                System.out.println("Mark2 : " + mark2);

                System.out.println("Total : " + total);

        }

        public static void main(String args[])

        {

                marks m1 = new marks(90,80);

                marks m2 = new marks(m1);

                marks m3 = new marks();

                m1.calc();

                m2.calc();

                m1.putdetails();

                m2.putdetails();

                m3.putdetails();

        }

}

Constructor Example

import java.io.*;

class students

{

        private int sno;

        private String sname;

        private int mark1,mark2,total;

        students() throws Exception

        {

            BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

            System.out.print("Enter Student No : ");

            sno = Integer.parseInt(br.readLine());

            System.out.print("Enter Student Name : ");

            sname = br.readLine();

            System.out.print("Enter mark1 and mark2 : ");

            mark1 = Integer.parseInt(br.readLine());

            mark2 = Integer.parseInt(br.readLine());

         }

        students(int no,String name,int m1,int m2)

        {

                sno = no;

                sname = name;

                mark1 = m1;

                mark2 = m2;

                total = mark1 + mark2;

        }

        void putstud()

        {

                System.out.println("Sno : " + sno);

                System.out.println("Sname : " + sname);

                System.out.println("Mark1 : " + mark1);

                System.out.println("Mark2 : " + mark2);

                System.out.println("Total  : " + total);

       }

        public static void main(String args[]) throws Exception

        {

                students s1 = new students();

                students s2 = new students(100,"Kirthika",90,80);

                s1.putstud();

                s2.putstud();

        }

}

Wrapper Classes example

import java.io.*;

class Const1

{

        private int sno;

        private String sname;

        Const1()

        {

                System.out.println("Constructor Called");

                sno = 0;

                sname = "";

        }

        void getdetails() throws IOException

        {

                BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

                String line;

                System.out.print("Enter Sno : ");

                line = br.readLine();

                sno = Integer.parseInt(line);

                System.out.print("Enter Sname : ");

                sname = br.readLine();

        }

       void putdetails()

        {

                System.out.println("Sno : " + sno);

                System.out.println("Sname : " + sname);

        }

        public static void main(String args[]) throws IOException

        {

                Const1 c1 = new Const1();

                c1.putdetails();

                c1.getdetails();

                c1.putdetails();

        }

}

This Keyword Example 1

class load

  {

        String firstname;

        String lastname;

        int age;

        String profession;

       load assign(String firstname,String lastname,int age,String profession)

        {

                this.firstname = firstname;

                this.lastname = lastname;

                this.age = age;

                this.profession = profession;

                return this;

        }

        load assign(String fn,String ln)

        {

                firstname = fn;

                lastname = ln;

                return this;

        }

        load assign(String fn,String ln,String prof)

        {

                firstname = fn;

                lastname = ln;

                profession = prof;

                return this;

        }

        load assign(String fn,int ag)

        {

                firstname = fn;

                age = ag;

                return this;

        }

        void print()

        {

                System.out.println(firstname + " " + lastname + " " + age + " " + profession);

        }

        public static void main(String args[])

        {

                load fl = new load();

                fl.assign("Naveen","Kumar",23,"Programmer");

                fl.print();

                fl.assign("Raj","Prabhu");

                fl.print();

                fl.assign("Chitra","Devi","Analyst");

                fl.print();

                fl.assign("Nithya",34);

                fl.print();

        }

}

This Keyword example

class point

            {

        int x,y;

       void init(int x,int y)

        {

                this.x = x;

                this.y = y;

        }

        void display()

        {

                System.out.println("x = " + x);

                System.out.println("y = " + y);

        }

}

class point1

{

        public static void main(String args[])

        {

                point pp = new point();

                pp.init(4,3);

                pp.display();

        }

}

Static Variables and Methods

class Rectangle

{

        int length;

        int breadth;

        private static int count;

        static void displaycount()

        {

                System.out.println("No of Object : " + count);

        }

        Rectangle(int a,int b)

        {

                length = a;

                breadth = b;

                count++;

        }

        Rectangle()

        {

                length = 0;

                breadth = 0;

                count++;

        }

        void display()

        {

                System.out.println("Length : " + length);

                System.out.println("Breadth : " + breadth);

        }

        public static void main(String args[])

        {

                Rectangle.displaycount();

                Rectangle r1 = new Rectangle(10,20);

                Rectangle.displaycount();

                Rectangle r2 = new Rectangle();

                Rectangle.displaycount();

            r1.display();

            r2.display();    

        }

}

Passing arguments and returning values.

Passing arguments and returning values.

class circle

{

        private int radius;

        public void setradius(int r)

        {

                radius = r;

        }

        public float calculate()

        {

                return 3.14f * radius * radius;

        }

        public static void main(String args[])

        {

                if (args.length < 1)

                {

                        System.out.println("Invalid Arguments");

                        System.exit(0);

                }

                circle c = new circle();

                c.setradius(Integer.parseInt(args[0]));

                float area = c.calculate();

                System.out.println("Radius : " + args[0]);

                System.out.println("Area : " + area);

        }

}