Java Map Interface

import java.util.*;  
public class Main {  
   public static void main(String args[]) {  
      // Creating a HashMap instance  
      // Here, the key is of type Integer, and the value is of type String
      Map<Integer, String> map = new HashMap<Integer, String>();     
      // Adding key-value pairs to the map  
      map.put(100, "Andrew");  
      map.put(101, "Tom");  
      map.put(99, "Jack");   
      // displaying the map 
      System.out.println(map);   
      
   }  
}  

import java.util.*;  
public class Main {  
   public static void main(String args[]) {  
      // Creating a HashMap instance  
      // Here, the key is of type Integer, and the value is of type String
      Map<Integer, String> map = new HashMap<Integer, String>();     
      // Adding key-value pairs to the map  
      map.put(100, "David");  
      map.put(101, "Robert");  
      map.put(99, "Emma");   
      // displaying the map 
      System.out.println(map);
      map.put(102, "Noah"); // value of key 100 is updated
      System.out.println("After updation: ");
      System.out.println(map);
   }  
}  

import java.util.*;  
public class Main {  
   public static void main(String args[]) {  
      // Creating a HashMap instance  
      // Here, the key is of type Integer, and the value is of type String
      Map<Integer, String> map = new HashMap<Integer, String>();     
      // Adding key-value pairs to the map  
      map.put(100, "Oliver");  
      map.put(101, "Theodore");  
      map.put(99, "Mary");   
      // displaying the map 
      System.out.println(map);
      map.remove(100); // key 100 is removed
      System.out.println("After removing key 100 and its mapping: ");
      System.out.println(map);
   }  
}  

import java.util.*;
public class Main {
    public static void main(String args[]) {
        // Creating an instance of HashMap
        // Here, Integer is the key, and String is the value
        Map<Integer, String> hm = new HashMap<Integer, String>();
        System.out.println("Traversing using for-each loop");
        // Inserting the Elements
        hm.put(1, "T");
        hm.put(2, "Point");
        hm.put(3, "Tech");
        hm.put(0, "Java");
        // for each loop
        for (Map.Entry mapEle : hm.entrySet()) {
            int key = (int)mapEle.getKey();
            // Finding the value
            String val = (String)mapEle.getValue();
            System.out.println(key + ": " + val);
        }
        System.out.println();
        System.out.println("Traversing using an iterator");
        // Traversing Map using iterator
        // Converting to Set so that we can traverse  
        Set set = hm.entrySet(); 
        Iterator itr = set.iterator();  
        while(itr.hasNext()) {  
            // Converting to Map.Entry so that we can get key and value separately  
            Map.Entry en = (Map.Entry)itr.next();  
            System.out.println(en.getKey() + ": " + en.getValue());  
        }
    }
}

import java.util.*;  
public class Main {  
    public static void main(String args[]) {  
        // Creating a HashMap instance to store key-value pairs  
        Map<Integer, String> map = new HashMap<Integer, String>();  
        // Adding key-value pairs to the map  
        map.put(100, "Smith");  
        map.put(101, "Williams");  
        map.put(102, "Johnson");  
        // Returns a Set view of the mappings contained in this map  
        map.entrySet() // Returns a Set view of the mappings contained in this map  
            .stream() // Returns a sequential Stream with this collection as its source  
            .sorted(Map.Entry.comparingByKey()) // Sorted according to the provided Comparator  
            .forEach(System.out::println); // Performs an action for each element of this stream  
    }  
}  

import java.util.*;  
public class Main {  
    public static void main(String args[]) {  
        // Creating a HashMap instance to store key-value pairs  
        Map<Integer, String> map = new HashMap<Integer, String>();  
        // Adding key-value pairs to the map  
        map.put(100, "Garcia");  
        map.put(101, "Williams");  
        map.put(102, "Liam");  
        // Returns a Set view of the mappings contained in this map  
        map.entrySet() // Returns a Set view of the mappings contained in this map  
            .stream() // Returns a sequential Stream with this collection as its source  
            .sorted(Map.Entry.comparingByKey(Comparator.reverseOrder())) // Sorted according to the provided Comparator  
            .forEach(System.out::println); // Performs an action for each element of this stream  
    }  
}