Java programs For Practice

import java.util.Scanner;
 
public class Fibonacci{
  public static void main(String args[]) {
    System.out.println("How many Fibonacci terms do you want? ");
    // creating a scanner object
    Scanner scn = new Scanner(System.in);
    int counter = scn.nextInt(); // taking the input with scanner
 
    int a = 0;
    int b = 1;
    int c, k;
    System.out.print(a + " " + b); // fib value for 0 and 1
 
    for (k = 2; k < counter; ++k) // looping starts from 2
    {
      c = a + b;
      System.out.print(" " + c);
      a = b;
      b = c;
    }
    scn.close();
  }
}

How many Fibonacci terms do you want? 7 
0 1 1 2 3 5 8

import java.util.Scanner;
 
public class Main {
 public static void main(String args[]) {
   System.out.println("Find the factorial of: ");
   // creating a scanner object
   Scanner scn = new Scanner(System.in);
   int number = scn.nextInt(); // taking the input with scanner
 
   int k, fact = 1; // first factorial value
 
   for (k = 1; k <= number; k++) {
     fact = fact * k;
   }
   System.out.println("Factorial of " + number + " is: " + fact);
   scn.close();
 }
}

Find the factorial of: 
6
Factorial of 6 is: 720

import java.util.Scanner;
 
public class Leap{
 
 public static void main(String[] args) {
   System.out.println("Check leap year for: ");
   Scanner scn = new Scanner(System.in); // scanner object
   int yr = scn.nextInt(); // taking the input with scanner
   boolean leap_yr = false;
 
   if (yr % 4 == 0) {
     if (yr % 100 == 0) {
       // if yr is divisible by 400 it is a leap year
       if (yr % 400 == 0)
         leap_yr = true;
       else
         leap_yr = false;
     } else
       leap_yr = true;
   } else
     leap_yr = false;
 
   if (leap_yr)
     System.out.println(yr + " is a leap year.");
   else
     System.out.println(yr + " is not a leap year.");
   scn.close();
 }
}

Check leap year for: 
1990
1990 is not a leap yr.

Check leap year for: 
2020
2020 is a leap year.

import java.util.Scanner;
 
public class Main {
 public static void main(String[] args) {
   System.out.println("Reversed string for: ");
   Scanner scn = new Scanner(System.in); // scanner object
   String str = scn.nextLine(); // taking the input with scanner
   // For storing the reverse of the given string
   String reversedStr = "";
 
   // Iterate string from last and add each character to reversedStr
   for (int s = str.length() - 1; s >= 0; s--) {
     reversedStr = reversedStr + str.charAt(s);
   }
 
   System.out.println("Original string: " + str);
   //reverse of the given string
   System.out.println("Reversed string: " + reversedStr);
   scn.close();
 }
}

Reversed string for: year
Original string: year
Reversed string: raey

import java.util.Arrays;
import java.util.Scanner;
public class Main {
 public static void main(String[] args) {
   // creating an object of Scanner class for input
   Scanner scn = new Scanner(System.in);
   // taking input from users with scn
   System.out.print("First String: ");
   String str_1 = scn.nextLine();
   System.out.print("Second String: ");
   String str_2 = scn.nextLine();
   if(str_1.length() == str_2.length()) {
     // converting strings to arrays
     char[] arr_1 = str_1.toCharArray();
     char[] arr_2 = str_2.toCharArray();
     // sorting the arrays
     Arrays.sort(arr_1);
     Arrays.sort(arr_2);
     boolean ang = Arrays.equals(arr_1, arr_2);
     if(ang) {
       System.out.println("The strings are valid anagram.");
     }
     else {
       System.out.println("The strings are not valid anagram.");
     }
   }
   else{
     System.out.println("The strings are not valid anagrams");
   }
   scn.close();
 }
}

First String: reader
Second String: read
The strings are not valid anagrams

import java.util.Scanner;
 
public class Main {
 public static void main(String[] args) {
 
   int vowel = 0;
   int consonant = 0;
   // creating an object of Scanner for input
   Scanner scn = new Scanner(System.in);
   // taking input from users with scn
   System.out.print("Your String: ");
   String strng = scn.nextLine();
 
   input = input.toLowerCase();
 
   for (int s = 0; s < strng.length(); s++) 
{
     if (strng.charAt(s) == 'a' || strng.charAt(s) == 'e' || strng.charAt(s) == 'i' || strng.charAt(s) == 'o'
         || strng.charAt(s) == 'u') {
       // Increments the vowel counter
       vowel++;
     } else if (strng.charAt(s) >= 'a' && strng.charAt(s) <= 'z') {
       consonant++;
     }
   }
   System.out.println("vowels: " + vowel);
   System.out.println("consonants: " + consonant);
   scn.close();
 }
}

Your String: the simplest string ever
Number of vowels: 6
Number of consonants: 15

public class Duplicate{
 public static void main(String[] args) {
 
   int[] array = new int[] { 1, 1, 2, 3, 5, 2, 3, 5, 7 };
 
   System.out.println("Founded these duplicate elements: ");
   for (int r = 0; r < array.length; r++) {
     for (int c = r + 1; c < array.length; c++) {
       if (array[r] == array[c])
         System.out.println(array[c]);
     }
   }
 }
}

Founded these duplicate elements: 
1
2
3
5

public class Sort {
 public static void main(String[] args) {
 
   // Initialize the original array
   int[] array = new int[] { 4,6,7,1,2,4 };
   int tmp = 0;
   int len = array.length
 
   // Sort the array in ascending order
   for (int h = 0; h < len; h++) {
     for (int c = h + 1; c < len; c++) {
       if (array[h] > array[c]) {
         tmp = array[k];
         array[h] = array[c];
         array[c] = tmp;
       }
     }
   }
 
   System.out.println();
 
   // Elements of array after sort
   System.out.println("Array after sorting: ");
   for (int h = 0; h < len; h++) {
     System.out.print(array[h] + " ");
   }
 }
}

Sorted elements: 
1 2 4 4 6 7

public class Main {
 public static void main(String[] args) {
   // Initialize array
   int[] arr = new int[] { 1, 1, 2, 3, 5 };
   len = arr.length
   System.out.println("reversed array : ");
   // Looping through array from last
   for (int h = len - 1; h >= 0; h--) {
     System.out.print(arr[h] + " ");
   }
 }
}

reversed array : 
5 3 2 1 1 

class Palindrome {
 static int pal(int num, int tmp) {
   // base case
   if (num == 0)
     return tmp;
   tmp = tmp * 10 + num % 10;
 
   return pal(num / 10, tmp);
 }
 
 public static void main(String[] args) {
   int num = 1221;
   int tmp = pal(num, 0);
 
   if (tmp == num)
     System.out.println("A palindrome number");
   else
     System.out.println("Not a palindrome number");
 }
}

A palindrome number

public class ReversedString {
   public String reverse(String strng){
   
      if(strng.isEmpty()){
         return strng;
      } else {
         return reverse(strng.substring(1))+strng.charAt(0);
      }
   }
   public static void main(String[] args) {
      ReversedString obj = new ReversedString();
      String result = obj.reverse("Fita Academy");
      System.out.println(result);
   }
}

ymedacA atiF

import java.util.Arrays;
import java.util.Scanner;
class Main {
// method to perform bubble sort
void bubble(int arry[]) {
  int len = arry.length;
  // for getting elements from array arry
  for (int m = 0; m < len - 1; m++) {
    // for comparison
    for (int n = 0; n < len - m - 1; n++) {
      // comparing with the next element
      if (arry[n + 1] < arry[n]) {
        // performing swap
        int temp = arry[n];
        arry[n] = arry[n + 1];
        arry[n + 1] = temp;
      }
    }
  }
}
// driver method
public static void main(String args[]) {
  int[] array = { -2, 4, -6, 0, 9 };
  // creating an object of Main
  Main bs = new Main();
  bs.bubble(array);
  System.out.println("Sorted array:");
  // for converting int to string
  System.out.println(Arrays.toString(array));
}
}

Sorted array:
[-6, -2, 0, 4, 9]

import java.util.Scanner;
import java.util.Arrays;
 
class Main {
 int binarySearch(int arr[], int element, int lower, int higher) {
 
   while (lower <= higher) {
 
     // get index of middle element
     int middle = lower + (higher - lower) / 2;
 
     // if element to be searched is middle
     if (arr[middle] == element)
       return middle;
 
     // if element is lesser than middle
     // search on the left of middle
     if (arr[middle] < element)
       lower = middle + 1;
 
     // if element is greater than middle
     // search on the right of middle
     else
       higher = middle - 1;
   }
 
   return -1;
 }
 
 public static void main(String args[]) {
 
   // create an object of the Main class
   Main obj = new Main();
 
   int[] arr = { 3, 4, 5, 6, 7, 8, 9 };
   int n = arr.length;
 
   // creating a scanner object to take input from a user
   Scanner scn = new Scanner(System.in);
 
   System.out.println("Element to be searched for:");
 
   int element = scn.nextInt();
   scn.close();
 
   int res = obj.binarySearch(arr, element, 0, n - 1);
   if (res == -1)
     System.out.println("Element not found in the array");
   else
     System.out.println("Element found in array at index " + res);
 }
}

Element to be searched for:
5
Element found in array at index 2