Sorting A 2D matrix.

import java.lang.*;
import java.io.*;
class Matrixkr
{

public static void main(String args[])    throws IOException
{
InputStreamReader ir=new InputStreamReader(System.in);
BufferedReader br=new BufferedReader(ir);

int temp=0;
System.out.println("enter no of rows");
int r=Integer.parseInt(br.readLine());
System.out.println("enter no of columns");
int c=Integer.parseInt(br.readLine());
int ar[][]=new int[r][c];
System.out.println("enter the elements");
       for(int i=0;i<r;i++)
{
for(int j=0;j<c;j++)
{
    ar[i][j]=Integer.parseInt(br.readLine());
}
}
for(int i=0;i<r;i++)
{
for(int j=0;j<c;j++)
{
    System.out.print(ar[i][j]+" ");
}
System.out.println();
}

for(int x=0;x<r;x++)
{
for(int y=0;y<c;y++)
{
for(int i=0;i<r;i++)
{
for(int j=0;j<c;j++)
{
if(ar[i][j]>ar[x][y])
{
temp=ar[x][y];
ar[x][y]=ar[i][j];
ar[i][j]=temp;
}

}

}

}

}
System.out.println("after sorting");
for(int i=0;i<r;i++)
{
for(int j=0;j<c;j++)
{
System.out.print(ar[i][j]+" ");
}
System.out.println();
}
}
}

Printing Pascal Triangle.

import java.util.Scanner;
class Pascal
{
static int factorial(int n)
{
  int sum = n;
  for(int k=n-1;k>=1;k--)
    sum*=k;
  if(sum!=0)
    return sum;
  else
    return 1;
}
public static void main(String...args)
{
  int s,lines;
  Scanner sc = new Scanner(System.in);
  System.out.println("Enter no of lines:");
  lines = sc.nextInt();
  for(int i=0;i<lines;i++)
  {
    for(int j=lines;j>i;j--)
      System.out.print(" ");
    for(int k=0;k<=i;k++)
    {
      s = factorial(i)/(factorial(k)*factorial(i-k));
      System.out.print(s+" ");
    }
    System.out.println();
  }
}
}

Small example of Interface.

interface A
{
int a=10;
void show();
}
class Interface implements A
{
public void show()
{
System.out.println("Show in class");
}
public static void main(String...args)
{
A i = new Interface();
i.show();
}
}

Example to prove that static each class object has the same static member(single copy of static member is maintained).

class Diff
{
static int m = 0;
int n = 0;
Diff()
{
  m = m+1;
  n = 10;
  }
public static void main(String...args)
{
  Diff ob1 = new Diff();
Diff ob2 = new Diff();
  System.out.println("Non static 1:"+ob1.m);
  System.out.println("Non static 2:"+ob2.m);
  System.out.println("Static 1:"+ob1.n);
  System.out.println("Static 2:"+ob1.n);
}
}

Inheriting Abstract Class and overriding their methods.

abstract class Player
{
abstract void play();
abstract void stop();
abstract void pause();
}
class GenericPlayer extends Player
{
void play()
{
  System.out.println("Generic: Can play .avi .dat files");
  }
void stop()
{
  System.out.println("Music stopped");
}
void pause()
{
  System.out.println("Music paused");
}
}
class DvdPlayer2 extends GenericPlayer
{
  void play()
{
  System.out.println("Dvd Player: Can play .avi .dat .mpg files");
}
public static void main(String...srgs)
{
Player pl = new DvdPlayer();
  Player pl1 = new GenericPlayer();
  pl.play();
  pl1.play();
}
}

Calculator By inheritance.

import java.util.Scanner;
import java.lang.Math;
class Calc
{
static int a,b;
static Scanner sc = new Scanner(System.in);
//////////////////////////////////////////
static void input1()
{
  System.out.println("Enter a no:");
  a = sc.nextInt();
  System.out.println("Enter a no:");
  b = sc.nextInt();
}
static void input2()
{
  System.out.println("Enter a no:");
  a = sc.nextInt();
}
/////////////////////////////////////////
static int add(int a,int b)
{
  return a+b;
}
static int sub(int a,int b)
{
return a-b;
}
static int mul(int a,int b)
  {
  return a*b;
}
static int div(int a,int b)
{
  return a/b;
}
static int sqr(int a)
{
  return a*a;
}
static double sqroot(double a)
{
  return Math.sqrt(a);
}
}
class Calculator extends Calc
{
static double c;
static void input3()
{
  System.out.println("Enter a no:");
c = sc.nextDouble();
}
  static double sine(double d)
{
  return Math.sin(Math.toRadians(d));
}
static double cosine(double d)
{
  return Math.cos(Math.toRadians(d));
}
static double tann(double d)
{
  return Math.tan(Math.toRadians(d));
  }
static double asine(double d)
{
    return Math.asin(d);
}
static double acosine(double d)
{
return Math.acos(d);
}
static double atann(double d)
{
  return Math.atan(d);
}
public static void main(String...args)
  {
  System.out.println("----Menu----");
  System.out.println("1.Add \n2.Sub \n3.Mul \n4.Div \n5.Sqr \n6.Sqr Root \n7.Sin \t\t8.Cos \t\t9.Tan \n10.Asin \t11.Acos \t12.Atan");
    int m = sc.nextInt();
  switch(m)
    {
  case 1:
    input1();
    System.out.println("\n"+a+"+"+b+"="+add(a,b));
    break;
  case 2:
    input1();
    System.out.println("\n"+a+"-"+b+"="+sub(a,b));
    break;
  case 3:
    input1();
    System.out.println("\n"+a+"*"+b+"="+mul(a,b));
    break;
  case 4:
    input1();
    System.out.println("\n"+a+"/"+b+"="+div(a,b));
    break;
  case 5:
      input2();
    System.out.println("\nSquare of "+a+"="+sqr(a));
    break;
  case 6:
    input2();
    System.out.println("\nSquare root of "+a+"="+sqroot(a));
    break;
    case 7:
    input3();
    System.out.println("\nSine("+c+")="+sine(c));
    break;
  case 8:
    input3();
    System.out.println("\nCos("+c+")="+cosine(c));
    break;
  case 9:
    input3();
    System.out.println("\nTan("+c+")="+tann(c));
    break;
  case 10:
    input3();
    System.out.println("\nAsin("+c+")="+asine(c));
    break;
  case 11:
    input3();
    System.out.println("\nACos("+c+")="+acosine(c));
    break;
  case 12:
    input3();
    System.out.println("\nAtan("+c+")="+atann(c));
    break;
    default:
    System.out.println("Wrong Entry");
}
}
}

Function Overloading

class Add
{
int add(int a,int b)
{
return a+b;
}
int add(int a,int b,int c)
{
return a+b+c;
}
int add(int a,int b,int c,int d)
{
return a+b+c+d;
}
public static void main(String...args)
{
Add obj = new Add();
System.out.println(obj.add(1,2));
System.out.println(obj.add(1,2,3));
System.out.println(obj.add(1,2,3,4));
}
}

Find area by taking their dimensions through command line argument.

class Area
{
      final double pi=3.14;
      void areaOfCircle(int r)
      {
          double area1=pi*r*r;
          System.out.println("area of circle="+area1);
       }
      void areaOfCylinder(int r,int h)
        {
          double area2=2*pi*r*(r+h);
          System.out.println("area of cylinder="+area2);
        }
    public static void main(String args[])
    {
int r1=Integer.parseInt(args[0]);
int h1=Integer.parseInt(args[1]);
           Area a = new Area();
           a.areaOfCircle(r1);
           a.areaOfCylinder(r1,h1);
    }
}

Find reverse of a number

import java.util.Scanner;
class Reverse
{
         int num;
        void getReverse(int a)
         {
                 num = a;
                 int r=0;
                 int reverse=0;
                 do
                 {
                            r=num%10;
                            reverse=reverse*10+r;
                            num=num/10;
                   }while(num>0);
                    System.out.println("Reverse= "+reverse);
           }
          public static void main(String args[])
           {
                 Scanner sc = new Scanner(System.in);
                 Reverse ob = new Reverse();
                 System.out.println("Enter a no: ");
                 int n = sc.nextInt();
                  ob.getReverse(n);
           }
}

Pattern Printing

1 2 3 4 5
1 2 3 4
1 2 3
1 2
1
1 2
1 2 3
1 2 3 4
1 2 3 4 5
---------------------------------------
public class Pattern
{
public static void main( String arg[])
{
int ck=0,c=2;
        while(c>0)
{
        if(ck==0)
{
            for(int i=1,r=5;i<=5;i++,r--)
{
            for(int j=1;j<=r;j++)
{
                System.out.print(j + " ");
            }
            System.out.println();
}
            ck++;
        }
else
{
            for(int i=2;i<=5;i++)
{
            for(int j=1;j<=i;j++)
{
                System.out.print(j + " ");
       }
            System.out.println();
        }
        }
        c--;
      }

}
}

Constructor Chaining.

class Const
{
Const()
{
  System.out.println("This is Default Const of class");
}
Const(int a)
{
  this();
  System.out.println("This is Param1 Const of class");
}
Const(int a,int b,int c)
{
  this(c);
  System.out.println("This is Param2 Const of class");
}
public static void main(String []ars)
{
  Const obj = new Const(4,5,8);
}
}

Use of SUPER keyword to invoke the constructor of parent class.

class Parent
{
int a;
Parent()
{
  System.out.println("This is Parent default constructor");
}
Parent(int x)
{
  a = x;
  System.out.println("This is Parent param constructor");
}
}
class Super extends Parent
{
int b;
Super()
{
  System.out.println("This is Super(child) Default constructor");
  }
Super(int z)
{
  super(z); //must be the first line of this constructor..
  System.out.println("This is Super(child) param constructor");
}
public static void main(String []ars)
{
  Super obj = new Super(8);
  Super obj1 = new Super();
  }
}

Print first 10 numbers from fibonacci series.

class Fibbonaci
{
  public static void main(String [] args)
  {
  int a = 0;
int b = 1, temp;
  System.out.print(a + ", " + b + ", ");
  for(int i = 1; i < 10; i++)
  {
    temp = b;
    b = a + b;
    a = temp;
    System.out.print(b + ", ");
  }
}
}

Factorial using recursion.

import java.util.Scanner;
class Factorial
{
static int fact(int num)
{
  if(num == 0)
  return 1;
  else
      return(num * fact(num-1));
}
public static void main(String [] args)
{
  System.out.println("Enter the number: ");
  Scanner sc = new Scanner(System.in);
  int inp = sc.nextInt();
  int ans = fact(inp);
  System.out.println("Factoral: "+ans);
}
}

Program to find first 5 Armstrong Numbers.

class Armstrong
{
public static void main(String []args)
  {
  int k = 0,temp=0,sum=0,i=0;
  while(k<5)
  {
    i = ++temp;
    sum = 0;
    temp = i;
    while(i>0)
    {
      sum = sum+((i%10)*(i%10)*(i%10));
      i=i/10;
    }
    if(temp == sum)
    {
      System.out.println("Armstrong"+(k+1)+"="+temp);
      k++;
    }
  }
}
}

Find whether a number is Prime or not.

import java.util.*;
class Prime
{
  public static void main(String []args)
  {
    int no=0,k=0;
Scanner sc = new Scanner(System.in);
  System.out.println("Enter a number:");
  no = sc.nextInt();
  for(int i=2;i<=no/2;i++)
  {
    if(no%i==0)
    {
      k=1;
      break;
    }
    }
  if(k==0)
    System.out.println("It is Prime");
  else
    System.out.println("It is not prime");
}
}

Finding Grades of Students by after taking input from user.

import java.util.*;
class Grade
{
  public static void main(String []args)
{
  int no;
  Scanner sc = new Scanner(System.in);
  System.out.println("Enter Marks[>=0 and <=100]:");
  no = sc.nextInt();
  System.out.println("Grade:");
  if(no<40)
    System.out.println("F");
  else if(no>=40 && no<60)
    System.out.println("C");
  else if(no>=60 && no<80)
    System.out.println("B");
  else if(no>=80 && no<=100)
    System.out.println("A");      //highest
}
}

Using Scanner class to take input from user and find Greater of two number using Ternary Operator.

import java.util.Scanner;
class Find
{
public static void main(String []args)
{
  Scanner sc = new Scanner(System.in);
  int i,j;
  System.out.println("Enter two nos:");
  i = sc.nextInt();
  j = sc.nextInt();
  System.out.println("Largest:"+((i>j)?i:j));
}
}

Dynamic Dispatch

class Base
{
  void show()
{
  System.out.println("This is Base Show");
}
}
class Dynamic extends Base
{
void show()
{
  System.out.println("This is Derived Show");
}
void disp()
  {
  System.out.println("This is Derived Disp");
}
public static void main(String []args)
{
  Base b = new Dynamic();
  b.show(); //storing reference of object of derived class in base class creates dynamic disp.
}
}

Use Of FINAL keyword

class Final
{
  final int a = 5;
public static void main(String [] args)
  {
  final int c; //makes c constant variable
  c = 10;
  Final obj = new Final();
  System.out.println(obj.a);
  }
}

Inheritance Example

class A
{
  int a = 10;
void show()
{
  System.out.println("Base class Var="+a);
}
}
class Inherit
{
int a = 20;
  void show()
{
  System.out.println("Inheriting class Var="+a);
}
public static void main(String []args)
{
  Inherit ob = new Inherit();
  ob.show();
}
}

Function Overloading

class Overload
{
  static void show(int a)
{
  System.out.println("Overloaded int A="+a);
}
static void show(float a)
{
  System.out.println("Overloaded Float A="+a);
}
public static void main(String []args)
{
  show(4);            //No need to call by object as method is static
  show(5.0f);
  }
}

This & Super - Use

class A
{
int a = 10;
}
class ThisSup extends A
{
int a = 20;
void show()
  {
    System.out.println("Base class Var="+super.a);
  }
  void disp()
{
  int a=99;
  System.out.println("Local Var="+a);
  System.out.println("This class Var="+this.a);
}
public static void main(String []args)
  {
  ThisSup ob = new ThisSup();
  ob.show();   ////base class variable
  ob.disp();
  System.out.println("Inheriting class Var="+ob.a);
  }
}

Typecasting Example

class Typecast
{
      static int a = 10;
      static long b = 20;
      public static void main(String []args)
      {
            a = (int)b;       ////explicit
            b = a;              //implicit
      }
}

JAVA-Intro

Java is a computer programming language that is concurrent, class-based, object-oriented, and specifically designed to have as few implementation dependencies as possible. It is intended to let application developers "write once, run anywhere" (WORA),meaning that code that runs on one platform does not need to be recompiled to run on another. Java applications are typically compiled to bytecode (class file) that can run on any Java virtual machine (JVM) regardless of computer architecture.