Java Coding Drill – One

1. Factorial finding

public class Fact {
        public static int factorial(int n) {
            if (n==0)
                  return 1;
           else
                 return n * factorial(n-1);
        }
        public static void main(String argv[]) {
             int x;
             x=9;
             System.out.println(“Factorial of “+x+” is “+factorial(x));
        }
}

2. Divisible by number

public class Divisor{
          public static void main(String[] args){
               int a = 10;
               int b = 2;
               if ( a % b == 0 ){
                      System.out.println(a + ” is divisible by “+ b);
              }else{
                      System.out.println(a + ” is not divisible by ” + b);
              }
         }
}

3. Compound Interest

public class CompoundInterest {
            public static void main(String[] args) {
               double principal;
               double rate;
               double interest;
               principal = 17000;
               rate = 0.07;
               interest = principal * rate; 
               principal = principal + interest;
               System.out.print(“The interest earned is $”);
               System.out.println(interest);
               System.out.print(“The value of the investment after one year is $”);
               System.out.println(principal);
          }
}

4. Printing Square of number

public class PrintSquare {
        public static void main(String[] args) throws Exception {
             int square = 0;
             int userInput = 0;
             userInput = Integer.parseInt(args[0]);
             square = userInput * userInput ;
             System.out.print(“The square of “+userInput+” is “+square);
        }
}

5. Sum of Numbers

     import java.util.*;
      public class SumNo{
            public static void main(String args[]){
                  Scanner console = new Scanner(System.in);
                  System.out.print(“Type a number: “);
                  int num1 = console.nextInt();
                  System.out.print(“Type a number: “);
                  int num2 = console.nextInt();
                  System.out.print(“Type a number: “);
                  int num3 = console.nextInt();
                  int sum = num1 + num2 + num3;
                  System.out.println(“The sum is ” + sum);
             }
      }

6. Finding even/odd numbers

public class EvenOdd{
       public static void main(String[] args) {
             for (int i = 1; i <= 20; i++) {
                  if (i % 2 == 0) {
                     System.out.println(i + ” is even”);
                  } else {
                     System.out.println(i + ” is odd”);
                  }
             }
       }
}

7. Finding Prime Number

public class PrimeNo {
         public static void main(String[] args) {
             for(int i=0;i<100;i++){
                  if(countFactor(i)==2){
                    System.out.println(i);
                  }
              }
          }
         public static int countFactor(int num){
              int cnt = 0;
              for(int j = 1; j <= num; j++) {
                 if (num % j == 0) {
                     cnt++;
                 }
               }
                return cnt;
           }
 }

8.Counting the charectors

public class CountChar {
      public static void main(String[] args) {
           String str = “mississippi”
           int tot = cntCh(str);
           System.out.println(“Total count :”+tot);
      }
      public static int cntCh(String str) {
          int count = 0;
          for (int i = 0; i < str.length(); i++) {
             if (str.charAt(i) == ‘s’) {
                  count++;
              }
         }
        return count;
      }
}

9. Printing Time and Date format

import java.util.*;
     public class TimeDateFormat {
         public static void main(String args[]) {
             Formatter fmt = new Formatter();
             Calendar cal = Calendar.getInstance();
             // Display standard 12-hour time format.
             fmt.format(“%tr”, cal);
             System.out.println(fmt); 
             // Display complete time and date information. 
             fmt = new Formatter();
             fmt.format(“%tc”, cal);
             System.out.println(fmt);
             // Display just hour and minute.
             fmt = new Formatter(); 
             fmt.format(“%tl:%tM”, cal, cal);
             System.out.println(fmt);
             // Display month by name and number.
             fmt = new Formatter();
             fmt.format(“%tB %tb %tm”, cal, cal, cal);
            System.out.println(fmt);
      }
}

10. Find In Line

import java.util.*;
        public class FindInLine{
            public static void main(String args[]) {
            String instr = “Name: Tom Age: 28 ID: 77”
            Scanner conin = new Scanner(instr); 
            // Find and display age.
            conin.findInLine(“Age:”); // find Age
            if(conin.hasNext())
                 System.out.println(conin.next());
            else
                  System.out.println(“Error!”);
         }
 }

11.File Read / Write

import java.util.*;
import java.io.*;
public class ScanMixed {
public static void main(String args[])
throws IOException {
int i;
double d;
boolean b;
String str;
// Write output to a file.
FileWriter fout = new FileWriter(“test.txt”);
fout.write(“Testing Scanner 10 12.2 one true two false”);
fout.close();
FileReader fin = new FileReader(“Test.txt”);
Scanner src = new Scanner(fin);
while(src.hasNext()) {
if(src.hasNextInt()) {
i = src.nextInt();
System.out.println(“int: ” + i);
}
else if(src.hasNextDouble()) {
d = src.nextDouble();
System.out.println(“double: ” + d);
}
else if(src.hasNextBoolean()) {
b = src.nextBoolean();
System.out.println(“boolean: ” + b);
}
else {
str = src.next();
System.out.println(“String: ” + str);
}
}
fin.close();
}
}

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2 Responses

  1. really good and useful those who start their carrier in java

    chocoguy

  2. Really good and usefull, for basic program (logic) understanding in java.
    Thanks
    Vipin Chauhan
    SE, SDGC Noida.

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