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Difference between Set and Map

Difference between Set and Map

Sets

Sets in Java represent a collection of unique elements. They do not allow duplicate elements, and they do not maintain any specific order of elements. Sets are primarily used when you need to store a collection of distinct values without caring about their order or frequency.

Maps

Maps in Java represent a collection of key-value pairs. Each key in a map must be unique, and it is associated with exactly one value. Maps do not maintain any specific order of key-value pairs. They are useful when you need to store and retrieve values based on some unique identifier or key.

Set and Map

Now, let’s provide Set and Map Java code examples to illustrate these concepts:

Example
Set Example:
java
import java.util.HashSet;
import java.util.Set;

public class SetExample {
    public static void main(String[] args) {
        // Creating a set
        Set<String> mySet = new HashSet<>();

        // Adding elements to the set
        mySet.add("Apple");
        mySet.add("Banana");
        mySet.add("Orange");
        mySet.add("Apple"); // Duplicate element, will be ignored
        
        // Iterating through the set
        System.out.println("Set elements:");
        for (String fruit : mySet) {
            System.out.println(fruit);
        }
    }
}

Example
Map Example:
java
import java.util.HashMap;
import java.util.Map;

public class MapExample {
    public static void main(String[] args) {
        // Creating a map
        Map<Integer, String> myMap = new HashMap<>();

        // Adding key-value pairs to the map
        myMap.put(1, "Apple");
        myMap.put(2, "Banana");
        myMap.put(3, "Orange");
        
        // Accessing value by key
        System.out.println("Value associated with key 2: " + myMap.get(2));

        // Iterating through the map
        System.out.println("Map elements:");
        for (Map.Entry<Integer, String> entry : myMap.entrySet()) {
            System.out.println("Key: " + entry.getKey() + ", Value: " + entry.getValue());
        }
    }
}

In the set example, Set and Map we create a HashSet, which is a type of set, and add some elements to it. Notice that when we try to add a duplicate element (“Apple”), it is ignored because sets do not allow duplicates.

In the map example, we create a HashMap, which is a type of map, and add some key-value pairs to it. We can then access values using their corresponding keys. Maps are useful when you need to associate unique keys with specific values.

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