Can Make Arithmetic Progression From Sequence

class Solution {
    public boolean canMakeArithmeticProgression(int[] arr) {
        Arrays.sort(arr);
        int prev = -1;
        boolean first = true;
        for(int i = 0; i<arr.length-1; i++){
                if(first){
                    prev = Math.abs(arr[i]-arr[i+1]);
                    first = false;
                }
                if(prev != Math.abs(arr[i] - arr[i+1])){
                    return false;
                }
            
        }
        return true;
    }
}