java - Why is my output being displayed as "[I@15db9742"?

Question

This question already has answers here: question from:https://stackoverflow.com/questions/65887909/why-is-my-output-being-displayed-as-i15db9742

Answer 1

You can use Arrays.toString to print an array:

private static String arrayToString(int[] arr) {
    return Arrays.toString(arr).replaceAll("\[|\]", "");
}

Or concatenate the elements using a StringBuilder and a for-loop:

private static String arrayToString(int[] arr) {
    StringBuilder sb = new StringBuilder();
    for(int i = 0; i < arr.length; i++) {
        String current = String.valueOf(arr[i]);
        if(i < arr.length-1) current += ", ";
        sb.append(current);
    }
    return sb.toString();
}

Demo:

int[] userAge;
userAge = new int[] {22,24,26,27,28};
System.out.println("The ages of my friends are " + arrayToString(userAge) + ".");

Output:

The ages of my friends are 22, 24, 26, 27, 28.