How to get the return String from a method stored in Hashmap?

September 16, 2022

I have the following method:

 public String randomValueGenerator(String item, int id){
        RandomGenerator randomGenerator = new RandomGenerator();
        HashMap<Integer, Runnable> map = new HashMap<Integer, Runnable>();
        map.put(1, () -> randomGenerator.generateFirstName());
        map.put(2, () -> randomGenerator.generateLastName());

        if (item==""){

            String rdn = map.get(id).run();
            return rdn;
        }else {
            return item;
        }
    }

I checking that the item is an empty string and if it is I would like to generate a random value and return it. (If not empty return as it was.)

I have problem with store the return String from the generateFirstName / generateLastName.

>Solution :

Try

public String randomValueGenerator(String item, int id){
        RandomGenerator randomGenerator = new RandomGenerator();
        // Use supplier instead of runnable
        HashMap<Integer, Supplier<String>> map = new HashMap<>(); 
        map.put(1, () -> randomGenerator.generateFirstName());
        map.put(2, () -> randomGenerator.generateLastName());

        if (item==""){

            String rdn = map.get(id).get(); //<-- get instead of run
            return rdn;
        }else {
            return item;
        }
    }

The ()-> is a lambda-notation. Runnable will return void, Supplier<String> will return String.

One more thing: You are comparing item=="" this might not always work, you better use item.intern()=="" or "".equals(item).

Edit: Please honor EdsonPassos comment item.isEmpty() is better than item.intern()=="".