Binary Search Opportunites

public static Integer search(List<Opportunity> opportunities, Integer target){
    // solution here
    Integer left = 0;
    Integer right = opportunities.size();
    while(left < right){
        Integer middle = Math.abs((left + right) / 2);
        if(opportunities[middle]. Amount == target)
            return middle;
        if(opportunities[middle].Amount < target){
            left = middle + 1;    
        }else{
            right = middle - 1;
        }
    }
    return - 1;
}