hashmap print in java code example

Example 1: how to print the map in java

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.stream.Stream;
 
class MapUtil
{
    // Program to print all keys present in the Map using keySet() in Java
    public static void main (String[] args)
    {
        Map<Integer, String> map = new HashMap<>();
        map.put(1, "One");
        map.put(2, "Two");
 
        // 1. using Iterator
        Iterator<Integer> itr = map.keySet().iterator();
        while (itr.hasNext()) {
            System.out.println(itr.next());
        }
 
        // 2. For-each Loop
        for (Integer key : map.keySet()) {
            System.out.println(key);
        }
 
        // 3. Java 8 - Collection.iterator() + Iterator.forEachRemaining()
        map.keySet().iterator()
                .forEachRemaining(System.out::println);
 
        // 4. Java 8 - Collection.stream() + Stream.forEach()
        map.keySet().stream()
                .forEach(System.out::println);
 
        // Java 8 - Stream.of() + Collection.toArray() + Stream.forEach()
        Stream.of(map.keySet().toArray())
                .forEach(System.out::println);
 
        // 5. Convert to String
        System.out.println(map.keySet().toString());
 
        // Java 8
        Stream.of(map.keySet().toString())
                .forEach(System.out::println);
    }
}

Example 2: print elements in map java

// Java 8 - Collection.iterator() + Iterator.forEachRemaining()
        map.keySet().iterator()
                .forEachRemaining(System.out::println);

Example 3: printing elemenst in hashmap

import java.util.HashMap;
import java.util.Map;
import java.util.Iterator;
import java.util.Set;
public class Details {

   public static void main(String args[]) {

      /* This is how to declare HashMap */
      HashMap<Integer, String> hmap = new HashMap<Integer, String>();

      /*Adding elements to HashMap*/
      hmap.put(12, "Chaitanya");
      hmap.put(2, "Rahul");
      hmap.put(7, "Singh");
      hmap.put(49, "Ajeet");
      hmap.put(3, "Anuj");

      /* Display content using Iterator*/
      Set set = hmap.entrySet();
      Iterator iterator = set.iterator();
      while(iterator.hasNext()) {
         Map.Entry mentry = (Map.Entry)iterator.next();
         System.out.print("key is: "+ mentry.getKey() + " & Value is: ");
         System.out.println(mentry.getValue());
      }

      /* Get values based on key*/
      String var= hmap.get(2);
      System.out.println("Value at index 2 is: "+var);

      /* Remove values based on key*/
      hmap.remove(3);
      System.out.println("Map key and values after removal:");
      Set set2 = hmap.entrySet();
      Iterator iterator2 = set2.iterator();
      while(iterator2.hasNext()) {
          Map.Entry mentry2 = (Map.Entry)iterator2.next();
          System.out.print("Key is: "+mentry2.getKey() + " & Value is: ");
          System.out.println(mentry2.getValue());
       }

   }
}