Save integer into vector after foor loop with conditionals

I have to set up a for loop that differences between odd and even numbers. I'm thinking to use an if/else statement into the for loop that evaluates de residue to know if is even or odd. Once done it, i'd like to save the number in a vector: one vector for the if condition, and another for the else.

This is my code!

import java.io.*;
import java.util.Arrays; 
import java.util.*;
  
class Even_odd_array { 
  
    static void CountingEvenOdd(int arr[], 
                              int arr_size) 
    { 
        int even_count = 0;          
        int odd_count = 0;  
        
        //int [] subvector_odd = {};
        Vector<Integer> vector_odd = new Vector<Integer>(); 
        Vector<Integer> vector_even = new Vector<Integer>(); 

              
        // loop to read all the values in 
        // the array 
        for(int i = 0 ; i < arr_size ; i++)  
        { 
            // checking if a number is  
            // completely divisible by 2 
            if ((arr[i] & 1) == 1) 
                odd_count ++ ; 
            	vector_odd.addElement(arr[i]);
            	
            else                
                even_count ++ ; 
            	vector_even.addElement(arr[i]);
        } 
      
        System.out.println( "Number of even"
               + " elements = " + even_count  
               + " Number of odd elements = "
                              + odd_count) ; 
        
        System.out.println(vector_odd); //This vector should look like [1, 3, 5, 7]
        
       
        
    } 
      
    // Driver Code 
    public static void main (String[] args)  
    { 
        int arr[] = {2, 4, 6, 8, 10, 1, 3, 5, 7}; 
        int n = arr.length; 
        CountingEvenOdd(arr, n); 
    } 
} 
  

The output should be:

Number of even elements = 5 Number of odd elements = 4
even_vector = [2, 4, 6, 8, 10]
odd_vector = [1, 3, 5, 7]

I'm getting an error in the else statement line when I include the vector.add() method inside the if statement, and I don't understand why...

Thanks!!

Currently your else block is not related to any if condition (you can omit curly braces if the block contains a single statement, though) .

To fix this, use curly braces to delimit the if and else blocks :

    if ((arr[i] & 1) == 1) {
        odd_count ++ ; 
        vector_odd.addElement(arr[i]);
    }
    else {                
        even_count ++ ; 
        vector_even.addElement(arr[i]);
    }

Your current code is equivalent to :

if ((arr[i] & 1) == 1) {
    odd_count ++ ;
} 

vector_odd.addElement(arr[i]);

else {                
    even_count ++ ; 
}

vector_even.addElement(arr[i]);

As you see, the else part can't be related to the if part here.

Modulo operator is %, not & which is bitwise and (see https://www.tutorialspoint.com/java/java_basic_operators.htm ). In addition, array length does not need to be given as parameter and a for loop is not needed. You have everything you need by using the two lines below.

Integer[] array = {2, 4, 6, 8, 1, 3, 7};
    Vector<Integer> vectorEven = Arrays.stream(array).filter(i -> i % 2 == 0).collect(Collectors.toCollection(Vector::new));
    Vector<Integer> vectorOdd =Arrays.stream(array).filter(i -> i % 2 == 1).collect(Collectors.toCollection(Vector::new));

    System.out.println(vectorEven);
    System.out.println(vectorOdd.size());