Java – even position letters in String to be categorized

public class UsingArrayGetEvenLettersFromString {

    public static void main(String[] args) {
        // even letters
        String str = new String("hello");
        char[] ch = str.toCharArray();
        char[] eCh = {};
        char[] oCh = {};
        System.out.println("length :"+ch.length);
        
        for(int i=0; i<ch.length; i++) {
            if(ch[i]%2 == 0) {
                eCh[i] = ch[i]; 
            }
            else {
                oCh[i] = ch[i];
            }
        }
        for (char c : eCh) {
            System.out.println(c);
        }
        for (char c : oCh) {
            System.out.println(c);
        }
    }
}

Error: length :5
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: Index 0 out of bounds for length 0
    at Strings.UsingArrayGetEvenLettersFromString.main(UsingArrayGetEvenLettersFromString.java:15)

I do not get what it does mean as far as I know … please suggest

>Solution :

Because when you make array you can’t change its size, and when you make array like this

char[] eCh = {};

it takes its length as zero.

You must give the array length first like this

char[] eCh = new char[str.length()];
char[] oCh = new char[str.length()];

Then you can use it normally.