Simplify nested if-else structure using the most suitable data structure

Question

I have a nested if-else block, where a series of conditions are present which need to be executed in a particular order. Below is a sample of the code.

        Map<String, String> DataHashMap = new HashMap<>();
        String SPECIES = "SPECIES";
        String NATIONALITY = "NATIONALITY";
        String STATE = "STATE";
        String GENDER = "GENDER";
        String OCCUPATION = "OCCUPATION";
        String HUMAN = "HUMAN";
        String AMERICAN = "AMERICAN";
        String WASHINGTON = "WASHINGTON";
        String FEMALE = "FEMALE";
        String BANKER = "BANKER";

        DataHashMap.put(SPECIES, HUMAN);
        DataHashMap.put(NATIONALITY, AMERICAN);
        DataHashMap.put(STATE, WASHINGTON);
        DataHashMap.put(GENDER, FEMALE);
        DataHashMap.put(OCCUPATION, BANKER);

        List<String> EligibilityList = new ArrayList<>();

        if (HUMAN.equals(DataHashMap.get(SPECIES))) {
            EligibilityList.add("H");
            if (AMERICAN.equals(DataHashMap.get(NATIONALITY))) {
                EligibilityList.add("A");
                if (WASHINGTON.equals(DataHashMap.get(STATE))) {
                    EligibilityList.add("W");
                    if (FEMALE.equals(DataHashMap.get(GENDER))) {
                        EligibilityList.add("F");
                        if (BANKER.equals(DataHashMap.get(OCCUPATION))) {
                            EligibilityList.add("B");
                        } else {
                            EligibilityList.add("NB");
                        }
                    } else {
                        EligibilityList.add("NF");
                    }
                } else {
                    EligibilityList.add("NW");
                }
            } else {
                EligibilityList.add("NA");
            }
        } else {
            EligibilityList.add("NH");
        }
        System.out.println(EligibilityList);

I need to modify the nested if-else structure using the most suitable and efficient data structure. Can anyone suggest a data structure that would do the above job efficiently? The constants, map, and list need to remain as it is (map is the input, and list the output).The if-else logic block can be modified

Answer 1

I would hold every condition in a list to process.

        String SPECIES = "SPECIES";
        String NATIONALITY = "NATIONALITY";
        String STATE = "STATE";
        String GENDER = "GENDER";
        String OCCUPATION = "OCCUPATION";
        String HUMAN = "HUMAN";
        String AMERICAN = "AMERICAN";
        String WASHINGTON = "WASHINGTON";
        String FEMALE = "FEMALE";
        String BANKER = "BANKER";
        
        Map<String, String> DataHashMap = new HashMap<>();
        DataHashMap.put(SPECIES, HUMAN);
        DataHashMap.put(NATIONALITY, AMERICAN);
        DataHashMap.put(STATE, WASHINGTON);
        DataHashMap.put(GENDER, FEMALE);
        DataHashMap.put(OCCUPATION, BANKER);
        
        List<List<String>> lookup = new ArrayList<>();
        lookup.add(Arrays.asList(SPECIES, HUMAN, "H", "NH"));
        lookup.add(Arrays.asList(NATIONALITY, AMERICAN, "A", "NA"));
        lookup.add(Arrays.asList(STATE, WASHINGTON, "W", "NW"));
        lookup.add(Arrays.asList(GENDER, FEMALE, "F", "NF"));
        lookup.add(Arrays.asList(OCCUPATION, BANKER, "B", "NB"));



        List<String> EligibilityList = new ArrayList<>();
        
        for(List<String> item : lookup){
            if (item.get(1).equals(DataHashMap.get(item.get(0)))) {
                EligibilityList.add(item.get(2));
            } else {
                EligibilityList.add(item.get(3));
                break;
            }
        }

        System.out.println(EligibilityList);