Step by Step solution about How to resolve the algorithm Associative array/Creation step by step in the Java programming language

Java Collections - HashMap, LinkedHashMap, TreeMap

HashMap:

• A HashMap stores key-value pairs.
• It uses a hash table to provide fast lookup based on the key.
• It is not ordered, meaning the order of elements is not guaranteed.
• It allows null keys and values.

LinkedHashMap:

• A LinkedHashMap extends HashMap.
• It maintains the insertion order of elements.
• It is useful when you need to access elements in the order they were added.

TreeMap:

• A TreeMap extends Map.
• It stores key-value pairs in a sorted order based on the keys.
• It uses a Red-Black tree to provide efficient sorting.
• It does not allow null keys but allows null values.

Code Explanation:

1. Create a HashMap:

2. Put key-value pairs into the HashMap:

3. Get the value associated with a key:

4. Replace the value for a key:

5. Replace a value only if the previous value matches:

6. Check if a key exists:

7. Check if a value exists:

8. Create a LinkedHashMap to maintain insertion order:

9. Create a TreeMap to store keys in sorted order:

10. Using a custom comparator to sort keys in a TreeMap:

    a. Create a Comparator class:

    b. Pass the comparator to the TreeMap constructor:

11. Using a lambda expression to define a comparator:

Map<String, Integer> map = new HashMap<>();


map.put("rosetta", 100);
map.put("code", 200);


int valueA = map.get("rosetta");
int valueB = map.get("code");


map.replace("rosetta", 300);


boolean replaced = map.replace("rosetta", 100, 300);


boolean contains = map.containsKey("rosetta");


boolean contains = map.containsValue(100);


Map<String, Integer> map = new LinkedHashMap<>();
map.put("rosetta", 100);
map.put("code", 200);


Map<String, Integer> map = new TreeMap<>();
map.put("rosetta", 100);
map.put("code", 200);


Comparator<String> comparator = new Comparator<String>() {
    public int compare(String stringA, String stringB) {
        if (stringA.compareTo(stringB) > 0) {
            return -1;
        } else if (stringA.compareTo(stringB) < 0) {
            return 1;
        }
        return 0;
    }
};


Map<String, Integer> map = new TreeMap<>(comparator);


Comparator<String> comparator = (stringA, stringB) -> {
    if (stringA.compareTo(stringB) > 0) {
        return -1;
    } else if (stringA.compareTo(stringB) < 0) {
        return 1;
    }
    return 0;
};