# If simplification

First if can be simplified to `input % 15`. Basically you are checking for number divisible by 3 and 5, so you can just check for 15. I agree with using brackets even here as mentioned by @Captain Man



    public String pickOne(int input) {

        if (input % 15 == 0) {
            return "fizzbuzz";
        } else if (input % 3 == 0) {
            return "fizz";
        } else if(input % 5 == 0) {
            return "buzz";
        }

        return String.valueOf(input);
    } 

# Constructing the string from pieces

You can reduce one if by removing "else" conditions. Downside is, that you need to add another `if` in the end for the return values so probably not better, but should be mentioned:

    public String pickOneV2(int input) {
        var sb = new StringBuilder();
        if (input % 3 == 0) {
            sb.append("fizz");
        }
        if (input % 5 == 0) {
            sb.append("buzz");
        }

        if (sb.length() == 0) {
            return String.valueOf(input); 
        }        
        return sb.toString();
    }

# Data-oriented approach

With all if conditions being in the same format, you can extract this into a data structure and simplify your code even more. I kept the map in the same method for simplicity reasons, but in reality it should be class property or a constant. This is the most extensible and clean I can think of, and you can easily modify this functionality purely by modifying the data without touching your code.

    public String pickOneV3(int input) {
        var fizzbuzzMap = new TreeMap<Integer, String>(Comparator.reverseOrder());
        fizzbuzzMap.put(3, "fizz");
        fizzbuzzMap.put(5, "buzz");
        fizzbuzzMap.put(15, "fizzbuzz");

        for (var index : fizzbuzzMap.keySet()) {
            if (input % index == 0) {
                return fizzbuzzMap.get(index);
            }
        }

        return String.valueOf(input);
    }


# Using stream API

Slightly nicer version (imho) using streams:

    public String pickOneV4(int input) {
        return fizzbuzzMap.entrySet().stream().filter(
                entry -> input % entry.getKey() == 0
        ).map(Map.Entry::getValue).findFirst().orElse(String.valueOf(input));
    }