Write a program of Fibonacci series using Recursion in Java

Code:

 import java.util.Scanner;  
 public class FibonacciRecursion {  
      public static void main(String args[]) {  
           Scanner scanner = new Scanner(System.in);  
           System.out.println("Enter the number for Fibonacci series:");  
           int num = scanner.nextInt();  
           System.out.println("Fibonacci Series:");  
           for (int i=0;i<num;i++) {  
           System.out.print(fibonacci(i) + ",");  
           }  
           scanner.close();  
      }  
      public static int fibonacci(int num) {  
           if (num == 0) {  
                return 0;  
           } else if (num == 1) {  
                return 1;  
           } else {  
                return fibonacci(num-2) + fibonacci(num-1);  
           }  
      }  
 }  

Output :
Enter the number for Fibonacci series:
8
Fibonacci series:
0,1,1,2,3,5,8,13,

Write a program to draw Pyramids using nested for loops in java

We are providing here code for drawing 6 Pyramids with the help of inner or nested for loops in Java.

Code :

 public class PrintPyramid {  
      public static void main(String args[])  
      {  
           //Pyramid One  
           for(int i=1;i<=5;i++)  
           {                 
                for(int j=1;j<=i;j++)  
                     {  
                          System.out.print("@ ");  
                     }  
                System.out.println();  
           }  
           //Pyramid Two  
           for(int i=1;i<=5;i++)  
           {                 
                for(int j=1;j<=5-i;j++)  
                     {  
                          System.out.print("# ");  
                     }  
                System.out.println();  
           }  
           //Pyramid Three  
           for(int i=1;i<=5;i++)  
           {                 
                for(int j=1;j<=5-i;j++)  
                     {  
                          System.out.print(j);  
                     }  
                System.out.println();  
           }  
           //Pyramid Four  
           for(int i=1;i<=5;i++)  
           {                 
                for(int j=1;j<=i;j++)  
                     {  
                          System.out.print(i);  
                     }  
                System.out.println();  
           }  
           //Pyramid Five  
           for(int i=1;i<=5;i++)  
           {                 
                for(int j=1;j<=5-i;j++)  
                     {  
                          System.out.print(" ");  
                     }  
                for(int k=1;k<=i;k++)  
                {  
                     System.out.print("% ");  
                }  
                System.out.println();  
           }  
           //Pyramid Six  
           for(int i=1;i<=5;i++)  
           {                 
                for(int j=1;j<=5-i;j++)  
                     {  
                          System.out.print(" ");  
                     }  
                for(int k=1;k<=i;k++)  
                {  
                     System.out.print("$ ");  
                }  
                for(int l=1;l<i;l++)  
                {  
                     System.out.print("$ ");  
                }  
                System.out.println();  
           }  
      }  
 }  

Output :

Write FizzBuzz Program in Java

Print numbers from 1 to 20, where print "Fizz" for multiple of 3, "Buzz" for multiple of 5, "FizzBuzz" for multiple of 3 and 5, and print numbers for others.

Code:

 public class PrintMultiple {  
      public static void main(String args[])  
      {  
           printMulti();  
      }  
      public static void printMulti()  
      {  
           for(int i=1;i<=20;i++)  
           {  
                //Method one
                /*if(i%3==0)  
                     System.out.println("Fizz");  
                else if(i%5==0)  
                     System.out.println("Buzz");  
                else if(i%15==0)   
                     System.out.println("FizzBuzz");  
                else   
                     System.out.println(i);*/  

                //Method Two
                if(i%3==0 && i%5!=0)  
                     System.out.println("Fizz");  
                if(i%5==0 && i%3!=0)  
                     System.out.println("Buzz");  
                if(i%15==0) /* or else if(i%3==0 && i%5==0)*/  
                     System.out.println("FizzBuzz");  
                if(i%3!=0 && i%5!=0 && i%15!=0)   
                     System.out.println(i);  
           }  
      }  
 }  

Output :
1
2
Fizz
4
Buzz
Fizz
7
8
Fizz
Buzz
11
Fizz
13
14
FizzBuzz
16
17
Fizz
19
Buzz

Write a program to print Fibonacci series in Java

Below is a program through which we are printing Fibonacci series in Java.

Code:

 import java.util.Scanner;  
 public class Fibonacci {  
      public static void main(String args[])  
      {  
           int num;  
           Scanner scanner=new Scanner(System.in);  
           System.out.println("Enter the number for Fibonacci series:");  
           num=scanner.nextInt();  
           findFibo(num);  
      }  
      public static void findFibo(int num)  
      {  
           int fibo[]=new int[num];  
           fibo[0]=0;  
           fibo[1]=1;  
           for(int i=2;i<num;i++)  
           {  
                fibo[i]=fibo[i-2]+fibo[i-1];  
           }  
           System.out.println("Fibonacci series");  
           for(int i=0;i<num;i++)  
           {  
                System.out.print(fibo[i]+",");  
           }  
      }  
 }  

Output :
Enter the number for Fibonacci series:
8
Fibonacci series
0,1,1,2,3,5,8,13,

Write a program to print factorial of a number in Java

The following is the code for printing Factorial  of a number.

Code:

 import java.util.Scanner;  
 public class Factorial {  
      public static void main(String args[])  
      {     int num;  
           Scanner in=new Scanner(System.in);  
           System.out.println("Enter a Number");  
           num=in.nextInt();  
           System.out.println("Factorial of "+num+" is : "+findFact(num));  
      }  
      public static int findFact(int num)  
      {  
           int fact=1;  
           for(int i=1;i<=num;i++)  
                fact=fact*i;  
           return fact;  
      }  
 }  

Output :
Enter a Number
5
Factorial of 5 is : 120

Write a program to Reverse a Number using array in Java

Here we are using array to reverse a number in Java.

Code:

 public class ReverseNumberA {  
      public static void main(String args[])  
      {   
           reverseNum(1203450);  
      }  
      public static void reverseNum(int num)  
      {  
           int length=String.valueOf(num).length();  
           int number[]=new int[length];  
           for(int n=0;n<=number.length-1;n++)  
           {  
                number[n]=num%10;  
                num=num/10;  
           }  
           System.out.println("Number after reverse :");  
           for(int n:number)  
           {  
                System.out.print(n);  
           }  
      }  
 }  

Output:
Number after reverse :
0543021

Write a program to Reverse a Number in Java

Use the below given code to reverse a number in Java.

Code:

 public class ReverseNumber {  
      public static void main(String args[])  
      {   
           System.out.println("Number after reverse :"+reverseNum(12345));  
      }  
      public static int reverseNum(int num)  
      {  
           int reverse=0;  
           while(num>0)  
           {  
           reverse=reverse*10 + num%10;  
           num=num/10;  
           }  
           return reverse;  
      }  
 }  

Output :
Number after reverse :54321

Write a program to find index where sum are equal from both ends in Java

We are using an array of numbers and Printing both the index(start and end index position) where we find out that sum of numbers from both the ends are equal.

Code :

 public class FindEqualSum {  
      public static void main(String args[])  
      {  
           int a[]={4,4,6,7,4,3};  
           findIndex(a);  
      }  
      public static void findIndex(int[] a)  
      {  
           int startindex=0;  
           int endindex=a.length-1;  
           int startsum=0;  
           int endsum=0;  
           while (true) {  
                if (startsum > endsum) {  
                     endsum = endsum + a[endindex--];  
                } else {  
                     startsum = startsum + a[startindex++];  
                }  
                if(startindex > endindex)  
                {  
                     if (startsum == endsum) {  
                          System.out.println("Match found on Start Index:"+ startindex);  
                          System.out.println("Match found on End Index:"+ endindex);  
                          break;  
                     } else {  
                          System.out.println("no match found");  
                          break;  
                     }  
                }  
           }  
      }  
 }  

Output:
Match found on Start Index:3
Match found on End Index:2

Write a program to Reverse a String using Recursion in Java

We are writing a program using Recursion method for Reversing a String.

Code:

 public class RecursiveReverseStr {  
      public static void main(String args[])  
      {  
           System.out.println(reverseStr("LoveJavaBytes"));  
      }  
      public static String reverseStr(String str)  
      {  
           String reverse="";  
      /*     if (str.length() == 1)  
                return str;  
           else {  
                reverse = reverse + str.charAt(str.length() - 1)   
                          + reverseStr(str.substring(0, str.length() - 1));  
                return reverse;  
           }*/  
           if(str.length() >= 1)  
           {  
                reverse = reverse + str.charAt(str.length() - 1)   
                          + reverseStr(str.substring(0, str.length() - 1));  
           }  
           return reverse;  
      }  
 }  

Output :
setyBavaJevoL

Write a program to Reverse a String in Java

You can simply use for loop for printing reverse string using charAt(index) method.

public char charAt(int index)
Returns the char value at the specified index. An index ranges from 0 to length() - 1. The first char value of the sequence is at index 0, the next at index 1, and so on, as for array indexing.

Code:

 public class ReverseString {  
      public static void main(String args[])  
      {  
           strReverse("LoveJavaBytes");  
      }  
      public static void strReverse(String str)  
      {  
           int size=str.length();  
           for(int i=size-1;i>=0;i--)  
                System.out.print(str.charAt(i));  
      }  
 }  

Output:
setyBavaJevoL

Write a program to find Duplicate Number in Java

Here we are adding 1 to 30 numbers in the List and one of the series number 29 is repeated. We need to find out that repeated or duplicate number.

Code :

 import java.util.ArrayList;  
 import java.util.List;  
 public class FindDuplicateNum {  
      public static void main(String args[])  
      {  
           List<Integer> numbers=new ArrayList<Integer>();  
           for(int i=1;i<=30;i++)  
                {  
                numbers.add(i);  
                }  
           numbers.add(29);  
           System.out.println("Duplicate Number is:"+ duplicateNum(numbers));  
      }  
      public static int sum(List<Integer> numbers)  
      { int sum=0;  
           for(int num:numbers)  
           {  
                sum+=num;  
           }  
           return sum;  
      }  
      public static int duplicateNum(List<Integer> numbers)  
      {    
           int n=numbers.size()-1;  
           int total=n*(n+1)/2;  
           int sum=sum(numbers);  
           return sum-total;  
      }  
 }  

Output:
Duplicate Number is:29

Write a program for Bubble Sort in Java

Bubble sort uses simple algorithm for sorting adjacent numbers with swapping each other by comparing both values one by one, which print order in the right manner. You can see the implemented code for Bubble Sort :

Code :

 public class BubbleSort {  
 public static void main(String args[])  
 {  
      int a[]={4,3,2,0,5,1};  
      System.out.println("Before Bubble Sort");  
      for(int i=0;i<a.length;i++)  
      {  
           System.out.print(a[i] + ",");  
      }  
      System.out.print("\n");  
      bubbleSort(a);  
      System.out.println("After Bubble Sort");  
      for(int i=0;i<a.length;i++)  
      {  
           System.out.print(a[i] + ",");  
      }  
 }  
 public static void bubbleSort(int a[])  
 {  
      int temp=0;  
      int n=a.length;  
      for(int i=0;i<n;i++)  
      {  
           for(int j=0;j<n-i-1;j++)  
           {  
                if(a[j]>a[j+1])  
                {  
                temp=a[j];  
                a[j]=a[j+1];  
                a[j+1]=temp;  
                }  
           }  
      }  
 }  
 }  

Output :
Before Bubble Sort
4,3,2,0,5,1,
After Bubble Sort
0,1,2,3,4,5,