Question

Could any one tell me how to correct following code to work correctly?

Write a method filterEvens which takes in an array of integers and returns a new array containing only the even values.

new array containing only the even values. Eg:

int[] data = {1, 3, 4, 2, 0, 5, -2};
int[] evens = filterEvens(data);

public static int[] filterEvent(int[] data) {
    int countLength = 0;

    for (int i = 0; i < data.length; i++) {
        if (data[i] % 2 == 0) {
            countLength++; 
        }
    }

    int[] filArray = new int[countLength]; 
    for (int i = 0; i < data.length; i++) {
        if (data[i] % 2 == 0) {
            filArray[i] = data[i]; 
        }
    }

    return filArray;  
}

Answer 1

The problem here is:

for (int i =0; i< data.length;i++)
  {
    if(data[i]%2==0)
    {
      filArray[i]= data[i] ; 
    }
}

You’re looping from values 0 –> data.length. That’s an issue because the array filArray[i] is of a smaller length.

Imagine it like this, you’re looking for someone’s house. On the street they give you, let’s say Emerald Dr. The house numbers can be from 2000 – 3000. Then you are told that they live at 4000 Emerald Dr. Same case here, except the computer is trying to find the house.