maps

import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.TreeMap;
import java.util.Map;

public class CollectionDemo {
    public static void main(String[] args) {
        // HashMap demonstration
        System.out.println("HashMap:");
        Map<String, Integer> hashMap = new HashMap<>();
        hashMap.put("Alice", 25);
        hashMap.put("Bob", 30);
        hashMap.put("Charlie", 35);
        for (Map.Entry<String, Integer> entry : hashMap.entrySet()) {
            System.out.println(entry.getKey() + ": " + entry.getValue());
        }

        // LinkedHashMap demonstration
        System.out.println("\nLinkedHashMap:");
        Map<String, Integer> linkedHashMap = new LinkedHashMap<>();
        linkedHashMap.put("Alice", 25);
        linkedHashMap.put("Bob", 30);
        linkedHashMap.put("Charlie", 35);
        for (Map.Entry<String, Integer> entry : linkedHashMap.entrySet()) {
            System.out.println(entry.getKey() + ": " + entry.getValue());
        }

        // TreeMap demonstration
        System.out.println("\nTreeMap:");
        Map<String, Integer> treeMap = new TreeMap<>();
        treeMap.put("Alice", 25);
        treeMap.put("Bob", 30);
        treeMap.put("Charlie", 35);
        for (Map.Entry<String, Integer> entry : treeMap.entrySet()) {
            System.out.println(entry.getKey() + ": " + entry.getValue());
        }
    }
}