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Java Program to Count Even and Odd Numbers in an Array

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How to write a Java Program to Count Even and Odd Numbers in an Array using For Loop, While Loop, and Functions with an example?.

Java Program to Count Even and Odd Numbers in an Array using For Loop

This Java program allows the user to enter the size and the One Dimensional Array elements. Next, it counts the total number of even and odd numbers within this array using For Loop.

// Java Program to Count Even and Odd Numbers in an Array using For Loop
import java.util.Scanner;
public class CountEvenOdd1 {
	private static Scanner sc;a
	public static void main(String[] args) 
	{
		int Size, i;
		int evenCount = 0, oddCount = 0;
		sc = new Scanner(System.in);
	 
		System.out.print(" Please Enter Number of elements in an array : ");
		Size = sc.nextInt();	
		
		int [] a = new int[Size];
		
		System.out.print(" Please Enter " + Size + " elements of an Array  : ");
		for (i = 0; i < Size; i++)
		{
			a[i] = sc.nextInt();
		}   

		for(i = 0; i < Size; i++)
		{
			if(a[i] % 2 == 0)
			{
				evenCount++;
			}
			else
			{
				oddCount++;
			}
		}		
		System.out.println("\n Total Number of Even Numbers in this Array = " + evenCount);
		System.out.println("\n Total Number of Odd  Numbers in this Array = " + oddCount);
	}
}

OUTPUT

Java Program to Count Even and Odd Numbers in an Array 1

ANALYSIS

First, we declared a One-dimensional Java array of specified user size. Next, we used For Loop to store the user entered values as array element such as a[0], a[1], a[2], a[3], a[4]

for (i = 0; i < Size; i++)
{
	a[i] = sc.nextInt();
}

In the next line, We have one more for loop to iterate each element. Within the Loop, we used the If statement.

Any number that is divisible by 2 is even number. Java If statement checks whether the remainder of the current array element divided by 2 is exactly equal to 0 or not.

  • If the condition is True, Even number and the compiler increment evenCount.
  • If the condition is False, Odd number. The Java compiler increment oddCount.
for(i = 0; i < Size; i++) {
	if(a[i] % 2 == 0) {
		evenCount++;
	}
	else {
		oddCount++;
	}
}

User inserted values for Java Program to Count Even and Odd Numbers in an Array are a[5] = {10, 25, 19, 26, 15}}

First Iteration: for (i = 0; 0 < 5; 0++)

The value of i is 0, and the condition (i < 5) is True. So, it starts executing the code inside the loop until the condition fails.

if(a[i] % 2 == 0) => if(a[0] % 2 == 0)
if(10 % 2 == 0) – Condition is True. So, evenCount becomes 1

Second Iteration: for (i = 1; 1 < 5; 1++)
The condition (i < 5) is True.

if(a[1] % 2 == 0)
if(25 % 2 == 0) – Condition is False. So, oddCount becomes 1

Do the same for the remaining iterations until the condition (i < 5) fails.

Java Program to Count Even and Odd Numbers in an Array using While Loop

This Java program is the same as above. But this time, we used While Loop to count the even and odd numbers an array.

// Java Program to Count Even and Odd Numbers in an Array using While Loop
import java.util.Scanner;
public class CountEvenOdd2 {
	private static Scanner sc;
	public static void main(String[] args) 
	{
		int Size, i = 0, j = 0;
		int evenCount = 0, oddCount = 0;
		sc = new Scanner(System.in);
	 
		System.out.print(" Please Enter Number of elements in an array : ");
		Size = sc.nextInt();	
		
		int [] a = new int[Size];
		
		System.out.print(" Please Enter " + Size + " elements of an Array  : ");
		while (i < Size)
		{
			a[i] = sc.nextInt();
			i++;
		}   

		while(j < Size)
		{
			if(a[j] % 2 == 0)
			{
				evenCount++;
			}
			else
			{
				oddCount++;
			}
			j++;
		}
		
		System.out.println("\n Total Number of Even Numbers in this Array = " + evenCount);
		System.out.println("\n Total Number of Odd  Numbers in this Array = " + oddCount);

	}
}

OUTPUT

Java Program to Count Even and Odd Numbers in an Array 2

Java Program to Count Even and Odd Numbers in an Array using Methods

This Java program is the same as the first example. But in this Java example, we created a separate method to count even numbers and another method to count odd numbers.

// Java Program to Count Even and Odd Numbers in an Array using Functions
import java.util.Scanner;
public class CountEvenOdd3 {
	private static Scanner sc;
	public static void main(String[] args) 
	{
		int Size, i;
		int evenCount = 0, oddCount = 0;
		sc = new Scanner(System.in);
	 
		System.out.print(" Please Enter Number of elements in an array : ");
		Size = sc.nextInt();	
		
		int [] a = new int[Size];
		
		System.out.print(" Please Enter " + Size + " elements of an Array  : ");
		for (i = 0; i < Size; i++)
		{
			a[i] = sc.nextInt();
		}   
		
		evenCount = CountEven(a, Size);
		oddCount = CountOdd(a, Size);		
		System.out.println("\n Total Number of Even Numbers in this Array = " + evenCount);
		System.out.println(" Total Number of Odd  Numbers in this Array = " + oddCount);

	}
	public static int CountEven(int [] a, int Size)
	{
		int i, evenCount = 0;
		System.out.print("\n List of Even Numbers in this Array are :");  
		for(i = 0; i < Size; i++)
		{
			if(a[i] % 2 == 0)
			{
				System.out.print(a[i] +" ");
				evenCount++;
			}
		}
		return evenCount;
	}
	public static int CountOdd(int [] a, int Size)
	{
		int i, oddCount = 0;
		System.out.print("\n List of Odd  Numbers in this Array are :");  
		for(i = 0; i < Size; i++)
		{
			if(a[i] % 2 != 0)
			{
				System.out.print(a[i] + " ");
				oddCount++;
			}
		}
		return oddCount;
	}
}

OUTPUT

Java Program to Count Even and Odd Numbers in an Array 3