Java Program

Program 1
//Find Maximum of 2 nos.
class Maxof2{
  public static void main(String args[]){
      //taking value as command line argument.
      //Converting String format to Integer value
      int i = Integer.parseInt(args[0]);
      int j = Integer.parseInt(args[1]);
      if(i > j)
          System.out.println(i+" is greater than "+j);
      else
          System.out.println(j+" is greater than "+i);
  }
}

---

Program 2
//Find Minimum of 2 nos. using conditional operator
class Minof2{
      public static void main(String args[]){
      //taking value as command line argument.
      //Converting String format to Integer value
      int i = Integer.parseInt(args[0]);
      int j = Integer.parseInt(args[1]);
      int result = (i<j)?i:j;
      System.out.println(result+" is a minimum value");
  }
}

---

Program 3
/* Write a program that will read a float type value from the   keyboard and print the following output.
   ->Small Integer not less than the number.
   ->Given Number.
   ->Largest Integer not greater than the number.
*/
class ValueFormat{
  public static void main(String args[]){
      double i = 34.32; //given number 
      System.out.println("Small Integer not greater than the number : "+Math.ceil(i));
      System.out.println("Given Number : "+i);
      System.out.println("Largest Integer not greater than the number : "+Math.floor(i));
  }

---

Program 4
/*Write a program to generate 5 Random nos. between 1 to 100, and it
  should not follow with decimal point.
*/
class RandomDemo{
      public static void main(String args[]){
          for(int i=1;i<=5;i++){
              System.out.println((int)(Math.random()*100));
          }
    }
}

---

Program 5
/* Write a program to display a greet message according to
   Marks obtained by student.
*/
class SwitchDemo{
      public static void main(String args[]){
          int marks = Integer.parseInt(args[0]);                //take marks as command line argument.
         switch(marks/10){
            case 10:
            case 9:
            case 8:
                     System.out.println("Excellent");
                     break;
            case 7:
                     System.out.println("Very Good");
                     break;
            case 6:
                     System.out.println("Good");
                     break;
            case 5:
                     System.out.println("Work Hard");
                     break;
            case 4:
                     System.out.println("Poor");
                     break;
            case 3:
            case 2:
            case 1:
            case 0:
                     System.out.println("Very Poor");
                     break;
            default:
                     System.out.println("Invalid value Entered");
      }
 }
}

---

Program 6
/*Write a program to find SUM AND PRODUCT of a given Digit. */
class Sum_Product_ofDigit{
      public static void main(String args[]){
            int num = Integer.parseInt(args[0]);         //taking value as command line argument.
            int temp = num,result=0;
            //Logic for sum of digit
            while(temp>0){
               result = result + temp;
               temp--;
            }
            System.out.println("Sum of Digit for "+num+" is : "+result);
            //Logic for product of digit
            temp = num;
            result = 1;
            while(temp > 0){
                 result = result * temp;
                 temp--;
            }
            System.out.println("Product of Digit for "+num+" is : "+result);
   }
}

---

Program 7
/*Write a program to Find Factorial of Given no. */
class Factorial{
      public static void main(String args[]){
          int num = Integer.parseInt(args[0]);                 //take argument as command line
          int result = 1;
          while(num>0){
                result = result * num;
                num--;
          }
          System.out.println("Factorial of Given no. is : "+result);
   }
}

---

Program 8
/*Write a program to Reverse a given no. */
class Reverse{
      public static void main(String args[]){
          int num = Integer.parseInt(args[0]);               //take argument as command line
          int remainder, result=0;
          while(num>0){
              remainder = num%10;
              result = result * 10 + remainder;
              num = num/10;
         }
         System.out.println("Reverse number is : "+result);
    }
}

---

Program 9
/*Write a program to find Fibonacci series of a given no.
  Example :
        Input - 8
        Output - 1 1 2 3 5 8 13 21
*/
class Fibonacci{
      public static void main(String args[]){
          int num = Integer.parseInt(args[0]);                        //taking no. as command line argument.
          System.out.println("*****Fibonacci Series*****");
          int f1, f2=0, f3=1;
          for(int i=1;i<=num;i++){
             System.out.print(" "+f3+" ");
             f1 = f2;
             f2 = f3;
             f3 = f1 + f2;
          }
   }
}

---

Program 10
/* Write a program to find sum of all integers greater than 100 and
   less than 200 that are divisible by 7 */
class SumOfDigit{
      public static void main(String args[]){
      int result=0;
      for(int i=100;i<=200;i++){
           if(i%7==0)
              result+=i;
      }
      System.out.println("Output of Program is : "+result);
   }
}
Program 11

/* Write a program to Concatenate  string using for Loop

   Example:
          Input - 5
          Output - 1 2 3 4 5 */
class Join{
      public static void main(String args[]){
      int num = Integer.parseInt(args[0]);
      String result = " ";
      for(int i=1;i<=num;i++){
           result = result + i + " ";
      }
      System.out.println(result);
  }
}

---

Program 12 
/* Program to Display Multiplication Table */
class MultiplicationTable{
      public static void main(String args[]){
      int num = Integer.parseInt(args[0]);
      System.out.println("*****MULTIPLICATION TABLE*****");
      for(int i=1;i<=num;i++){
         for(int j=1;j<=num;j++){
            System.out.print(" "+i*j+" ");
         }
         System.out.print("\n");
      }
  }
}

---

Program 13
/* Write a program to Swap the values */
class Swap{
      public static void main(String args[]){
      int num1 = Integer.parseInt(args[0]);
      int num2 = Integer.parseInt(args[1]);
      System.out.println("\n***Before Swapping***");
      System.out.println("Number 1 : "+num1);
      System.out.println("Number 2 : "+num2);
      //Swap logic
      num1 = num1 + num2;
      num2 = num1 - num2;
      num1 = num1 - num2;
      System.out.println("\n***After Swapping***");
      System.out.println("Number 1 : "+num1);
      System.out.println("Number 2 : "+num2);
      }
}

---

Program 14
/* Write a program to convert given no. of days into months and days.
  (Assume that each month is of 30 days)
  Example :
           Input - 69
           Output - 69 days = 2 Month and 9 days */
class DayMonthDemo{
      public static void main(String args[]){
      int num = Integer.parseInt(args[0]);
      int days = num%30;
      int month = num/30;
      System.out.println(num+" days = "+month+" Month and "+days+" days");
   }
}

---

Program 15
/*Write a program to generate a Triangle.
  eg:
  1
  2 2
  3 3 3
  4 4 4 4 and so on as per user given number */
class Triangle{
      public static void main(String args[]){
          int num = Integer.parseInt(args[0]);
          for(int i=1;i<=num;i++){
             for(int j=1;j<=i;j++){
                System.out.print(" "+i+" ");
             }
             System.out.print("\n");
           } 
    }
}

---

Program 16
/* Write a program to Display Invert Triangle.
   Example:
          Input - 5
          Output :
          5 5 5 5 5
          4 4 4 4
          3 3 3
          2 2
          1
*/
class InvertTriangle{
      public static void main(String args[]){
           int num = Integer.parseInt(args[0]);
           while(num > 0){
              for(int j=1;j<=num;j++){
                  System.out.print(" "+num+" ");
                }
                System.out.print("\n");
                num--;
            }
      }
}

---

Program 17
/*Write a program to find whether given no. is Armstrong or not.
  Example :
           Input - 153
           Output - 1^3 + 5^3 + 3^3 = 153, so it is Armstrong no. */
class Armstrong{
      public static void main(String args[]){
      int num = Integer.parseInt(args[0]);
      int n = num; //use to check at last time
      int check=0,remainder;
      while(num > 0){
           remainder = num % 10;
           check = check + (int)Math.pow(remainder,3);
           num = num / 10;
      }
      if(check == n)
            System.out.println(n+" is an Armstrong Number");
      else
            System.out.println(n+" is not a Armstrong Number");
   }
}

---

Program 18
/* Write a program to Find whether number is Prime or Not. */
class PrimeNo{
      public static void main(String args[]){
          int num = Integer.parseInt(args[0]);
         int flag=0;
         for(int i=2;i<num;i++){
             if(num%i==0)
              {
                 System.out.println(num+" is not a Prime Number");
                 flag = 1;
                 break;
              }
         }
         if(flag==0)
             System.out.println(num+" is a Prime Number");
    }
}

---

Program 19
/* Write a program to find whether no. is palindrome or not.
   Example :
           Input - 12521 is a palindrome no.
           Input - 12345 is not a palindrome no. */
class Palindrome{
      public static void main(String args[]){
          int num = Integer.parseInt(args[0]);
          int n = num; //used at last time check
          int reverse=0,remainder;
          while(num > 0){
                remainder = num % 10;
                reverse = reverse * 10 + remainder;
                num = num / 10;
           }
          if(reverse == n)
              System.out.println(n+" is a Palindrome Number");
          else
              System.out.println(n+" is not a Palindrome Number");
     }
}
Program 20
/* switch case demo
   Example :
           Input - 124
           Output - One Two Four */

class SwitchCaseDemo{
      public static void main(String args[]){
          try{
          int num = Integer.parseInt(args[0]);
          int n = num; //used at last time check
          int reverse=0,remainder;
          while(num > 0){
                remainder = num % 10;
                reverse = reverse * 10 + remainder;
                num = num / 10;
           }
          String result=""; //contains the actual output
          while(reverse > 0){
               remainder = reverse % 10;
               reverse = reverse / 10;
               switch(remainder){
                    case 0 :
                             result = result + "Zero ";
                             break;
                    case 1 :
                             result = result + "One ";
                             break;
                    case 2 :
                             result = result + "Two ";
                             break;
                    case 3 :
                             result = result + "Three ";
                             break;
                    case 4 :
                             result = result + "Four ";
                             break;
                    case 5 :
                             result = result + "Five ";
                             break;
                    case 6 :
                             result = result + "Six ";
                             break;
                    case 7 :
                             result = result + "Seven ";
                             break;
                    case 8 :
                             result = result + "Eight ";
                             break;
                    case 9 :
                             result = result + "Nine ";
                             break;
                    default:
                             result="";
                 }
            }
                System.out.println(result);
        }catch(Exception e){
             System.out.println("Invalid Number Format");
         }
     }
}

---

Program 21
/* Write a program to generate Harmonic Series.
   Example :
           Input - 5
           Output - 1 + 1/2 + 1/3 + 1/4 + 1/5 = 2.28 (Approximately) */
class HarmonicSeries{
      public static void main(String args[]){
      int num = Integer.parseInt(args[0]);
      double result = 0.0;
      while(num > 0){
            result = result + (double) 1 / num;
            num--;
      }
      System.out.println("Output of Harmonic Series is "+result);
  }
}

---

Program 22
/*Write a program to find average of consecutive N Odd no. and Even no. */
class EvenOdd_Avg{
      public static void main(String args[]){
      int n = Integer.parseInt(args[0]);
      int cntEven=0,cntOdd=0,sumEven=0,sumOdd=0;
      while(n > 0){
           if(n%2==0){
               cntEven++;
               sumEven = sumEven + n;
           }
           else{
               cntOdd++;
               sumOdd = sumOdd + n;
           }
           n--;
      }
      int evenAvg,oddAvg;
      evenAvg = sumEven/cntEven;
      oddAvg = sumOdd/cntOdd;
      System.out.println("Average of first N Even no is "+evenAvg);
      System.out.println("Average of first N Odd no is "+oddAvg);

  }
}

---

Program 23
/* Display Triangle as follow : BREAK DEMO.
    1
    2 3
    4 5 6
    7 8 9 10 ... N */
class Output1{
      public static void main(String args[]){
          int c=0;
          int n = Integer.parseInt(args[0]);
         loop1: for(int i=1;i<=n;i++){
         loop2: for(int j=1;j<=i;j++){
                       if(c!=n){
                            c++;
                            System.out.print(c+" ");
                       }
                       else
                           break loop1;
                    }
                    System.out.print("\n");
                 }
     }
}

---

Program 24
/* Display Triangle as follow
    0
    1 0
    1 0 1
    0 1 0 1 */
class Output2{
      public static void main(String args[]){
           for(int i=1;i<=4;i++){
              for(int j=1;j<=i;j++){
                            System.out.print(((i+j)%2)+" ");
                    }
                    System.out.print("\n");
                 }
     }
}       

---

Program 25
/* Display Triangle as follow
    1
    2 4
    3 6 9
    4 8 12 16 ... N (indicates no. of Rows) */
class Output3{
      public static void main(String args[]){
          int n = Integer.parseInt(args[0]);
                   for(int i=1;i<=n;i++){
                     for(int j=1;j<=i;j++){
                        System.out.print((i*j)+" ");
                    }
                    System.out.print("\n");
                 }
     }

}
JAVA Date Utility
( This program Demonstrates the proper use of Date functionality in common java programming scenarios )
Date and Time

import java.text.DateFormat;

import java.text.ParseException;

import java.text.SimpleDateFormat;

import java.util.Calendar;

import java.util.Date;

public class DateUtility {

/* Add Day/Month/Year to a Date

add() is used to add  values to a Calendar object. 

You specify which Calendar field is to be affected by the operation 

(Calendar.YEAR, Calendar.MONTH, Calendar.DATE). 

*/

        public static void addToDate(){

               System.out.println("In the ADD Operation");

        //      String DATE_FORMAT = "yyyy-MM-dd";

               String DATE_FORMAT = "dd-MM-yyyy";            //Refer Java DOCS for formats

               java.text.SimpleDateFormat sdf =  new java.text.SimpleDateFormat(DATE_FORMAT);

               Calendar c1 = Calendar.getInstance();

               Date d1 = new Date();

               System.out.println("Todays date in Calendar Format : "+c1);

               System.out.println("c1.getTime() : "+c1.getTime());

               System.out.println("c1.get(Calendar.YEAR): " + c1.get(Calendar.YEAR));

               System.out.println("Todays date in Date Format : "+d1);

               c1.set(1999,0 ,20);            //(year,month,date)

               System.out.println("c1.set(1999,0 ,20) : "+c1.getTime());

               c1.add(Calendar.DATE,40);

               System.out.println("Date + 20 days is : " + sdf.format(c1.getTime()));

                System.out.println();

               System.out.println();

        }

/*Substract Day/Month/Year to a Date

        roll() is used to substract values to a Calendar object. 

        You specify which Calendar field is to be affected by the operation 

        (Calendar.YEAR, Calendar.MONTH, Calendar.DATE). 

        Note: To substract, simply use a negative argument. 

    roll() does the same thing except you specify if you want to roll up (add 1) 

    or roll down (substract 1) to the specified Calendar field. The operation only

    affects the specified field while add() adjusts other Calendar fields. 

    See the following example, roll() makes january rolls to december in the same 

    year while add() substract the YEAR field for the correct result

*/

        public static void subToDate(){

               System.out.println("In the SUB Operation");

               String DATE_FORMAT = "dd-MM-yyyy";

               java.text.SimpleDateFormat sdf = new java.text.SimpleDateFormat(DATE_FORMAT);

               Calendar c1 = Calendar.getInstance(); 

               c1.set(1999, 0 , 20); 

               System.out.println("Date is : " + sdf.format(c1.getTime()));

               // roll down, substract 1 month

               c1.roll(Calendar.MONTH, false); 

               System.out.println("Date roll down 1 month : " + sdf.format(c1.getTime())); 

               c1.set(1999, 0 , 20); 

               System.out.println("Date is : " + sdf.format(c1.getTime()));

               c1.add(Calendar.MONTH, -1); 

               // substract 1 month

               System.out.println("Date minus 1 month : " + sdf.format(c1.getTime())); 

               System.out.println();

               System.out.println();

        }

        public static void daysBetween2Dates(){

               Calendar c1 = Calendar.getInstance();         //new GregorianCalendar();

               Calendar c2 = Calendar.getInstance();         //new GregorianCalendar();

            c1.set(1999, 0 , 20); 

            c2.set(1999, 0 , 22); 

            System.out.println("Days Between "+c1.getTime()+"\t"+ c2.getTime()+" is");

            System.out.println((c2.getTime().getTime() - c1.getTime().getTime())/(24*3600*1000));

            System.out.println();

               System.out.println();

        }

        public static void daysInMonth() {

               Calendar c1 = Calendar.getInstance();         //new GregorianCalendar();

            c1.set(1999, 6 , 20); 

            int year = c1.get(Calendar.YEAR);

            int month = c1.get(Calendar.MONTH);

//          int days = c1.get(Calendar.DATE);

               int [] daysInMonths = {31,28,31,30,31,30,31,31,30,31,30,31};

               daysInMonths[1] += DateUtility.isLeapYear(year) ? 1 : 0;

               System.out.println("Days in "+month+"th month for year "+year+" is "+ daysInMonths[c1.get(Calendar.MONTH)]);

            System.out.println();

               System.out.println();

        }

        public static void getDayofTheDate() {

               Date d1 = new Date();

               String day = null;

            DateFormat f = new SimpleDateFormat("EEEE");

            try {

             day = f.format(d1);

            }

            catch(Exception e) {

              e.printStackTrace();

            }

            System.out.println("The dat for "+d1+" is "+day);

            System.out.println();

               System.out.println();

        }

        public static void validateAGivenDate() {

               String dt = "20011223";   

               String invalidDt = "20031315";

               String dateformat = "yyyyMMdd";   

               Date dt1=null , dt2=null;

               try {     

                       SimpleDateFormat sdf = new SimpleDateFormat(dateformat);    

                       sdf.setLenient(false);    

                       dt1 = sdf.parse(dt);  

                       dt2 = sdf.parse(invalidDt);   

                       System.out.println("Date is ok = " + dt1 + "(" + dt + ")");     

               }  

               catch (ParseException e) {     

                       System.out.println(e.getMessage()); 

               }  

               catch (IllegalArgumentException e) {    

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

               }

            System.out.println();

               System.out.println();

        }

        public static void compare2Dates(){

               SimpleDateFormat fm = new SimpleDateFormat("dd-MM-yyyy");

               Calendar c1 = Calendar.getInstance();

               Calendar c2 = Calendar.getInstance();

               c1.set(2000, 02, 15);

               c2.set(2001, 02, 15);

               System.out.print(fm.format(c1.getTime())+" is ");

               if(c1.before(c2)){

                       System.out.println("less than "+c2.getTime());

               }else if(c1.after(c2)){

                       System.out.println("greater than "+c2.getTime());

               }else if(c1.equals(c2)){

                       System.out.println("is equal to "+fm.format(c2.getTime()));

               }

               System.out.println();

               System.out.println();

        }

        public static boolean isLeapYear(int year){

                if((year%100 != 0) || (year%400 == 0)){

                        return true;

                }

                return false;

        }

        public static void main(String args[]){

               addToDate();

               subToDate();

               daysBetween2Dates();   //The "right" way would be to compute the julian day number of both dates and then do the substraction.

               daysInMonth();

               validateAGivenDate();

               compare2Dates();

               getDayofTheDate();

        }

}

JAVA String Utility
( This program Demonstrates the proper use of Number Formats in common java programming scenarios )
String Utility

/*

 * NumberUtility.java

 *

 *  Source:  http://www.freejavaguide.com  

 */

import java.math.BigDecimal;

import java.text.DecimalFormat;

import java.text.DecimalFormatSymbols;

import java.util.Locale;

/**

 * Class provides common functions on number formats.

 */

public class NumberUtility {

    /**

     * Method takes Object as parameter and returns decimal number.

     * if argument is float or double and contains tailing zeros

     * it removes them. If argument is float or double then no change in return type.

     * Change the Format of the Number by changing the String Pattern

     */

    public static String changeToDecimalFormat(Object number) {

        BigDecimal bdNumber = new BigDecimal(number.toString());

        bdNumber = bdNumber.stripTrailingZeros();           //Returns a BigDecimal with any trailing zero's removed

        String pattern = "###,##0.0###########";             //To apply formatting when the number of digits in input equals the pattern

        DecimalFormat newFormat = new DecimalFormat(pattern, new DecimalFormatSymbols(Locale.US));

        return newFormat.format(bdNumber);

    }

    /* Method takes Object as parameter and removes commas from the parameter */

    public static double removeCommasFromNumber(Object number) {

        try {

            StringBuffer inputNo = new StringBuffer(number.toString());

            if (inputNo.length() > 0) {

                while (inputNo.indexOf(",") != -1) {

                    inputNo.deleteCharAt(inputNo.indexOf(","));

                }

            } else {

                return 0.0;

            }

            return Double.parseDouble(inputNo.toString());

        } catch (NumberFormatException e) {

            return 0.0;

        }

    }

    /* Some times its required to have a fixed set of decimal places for a 

     * number. We can set that by changing the precision number for a particular

     * input BigDecimal Input String

     */

    public static String changeToRequiredDecimals(String bigDecimalString,

            int precision) {

        String newFormattedString = null;

        String afterDecimal = null;

        if (bigDecimalString == null || bigDecimalString.length() == 0) {

            return "0.0";

        }

        if (bigDecimalString.contains(".")) {

            afterDecimal = bigDecimalString.substring(bigDecimalString

                    .indexOf(".") + 1);

            int length = Math.abs((afterDecimal.length() - precision));

            if (afterDecimal.length() < precision) {

                newFormattedString = bigDecimalString;

                for (int i = 0; i < length; i++) {

                    newFormattedString = newFormattedString + "0";

                }

            } else if (afterDecimal.length() > precision) {

                newFormattedString = bigDecimalString.substring(0,

                        bigDecimalString.length() - length);

                if (precision == 0) {

                    newFormattedString = newFormattedString.substring(0,

                            newFormattedString.indexOf("."));

                    } else {

                        newFormattedString = bigDecimalString;

                    }

                } else {

                           if (precision > 0)

                               newFormattedString = bigDecimalString + ".";

                           else

                               newFormattedString = bigDecimalString;

                           for (int i = 0; i < precision; i++) {

                               newFormattedString = newFormattedString + "0";

                           }

                }

        }

        return newFormattedString;

    }

    public static void main(String args[]){

        int intVar = 10;

        double doubleVar = 10.504000;

        float floatVar = 343534534348.5687654F;

        String commaString = "343,534,535,000.0";

        BigDecimal bdNumber = new BigDecimal("1234.8765");

        System.out.println(NumberUtility.changeToDecimalFormat(new Integer(intVar)));

        System.out.println(NumberUtility.changeToDecimalFormat(new Double(doubleVar)));

        System.out.println(NumberUtility.changeToDecimalFormat(new Float(floatVar)));

        System.out.println(NumberUtility.removeCommasFromNumber(commaString));

        System.out.println(NumberUtility.changeToRequiredDecimals(bdNumber.toString(), 8));

    }

}