How to print Map in Java 10 - Printing HashMap In Java 10

Overview

In this tutorial, we show you how to print out all keys and values in Map (HashMap) in Java 10.

How to print Map in Java 10

Reference Tutorials

Print all keys and values in HashMap using forEach + lambda expression

package com.jackrutorial;

import java.util.HashMap;

public class PrintingHashmapExample1 {

 public static void main (String[] args) {
  var map = new HashMap<>();
        map.put(1, "Java");
        map.put(2, "Spring MVC");
        map.put(3, "AngularJS");
        
        //Using forEach + lambda expression
        System.out.println("Using forEach + lambda expression");
        map.forEach((k,v) -> System.out.println(k + " - " + v));
        
        //Using for each loop
        System.out.println("Using for each loop");
        for (var key : map.keySet()) {
            System.out.println("key: " + key);
        }
        
        for (var value : map.values()) {
            System.out.println("value: " + value);
        }
 }
}

Output

Using forEach + lambda expression
1 - Java
2 - Spring MVC
3 - AngularJS
Using for each loop
key: 1
key: 2
key: 3
value: Java
value: Spring MVC
value: AngularJS

Print all keys and values in HashMap using Collection.iterator() & Iterator.forEachRemaining()

package com.jackrutorial;

import java.util.HashMap;

public class PrintingHashmapExample2 {

 public static void main (String[] args) {
  var map = new HashMap<>();
        map.put(1, "Java");
        map.put(2, "Spring MVC");
        map.put(3, "AngularJS");
        
        //Using Collection.iterator() & Iterator.forEachRemaining()
        System.out.println("Using Collection.iterator() & Iterator.forEachRemaining()");
        map.keySet().iterator().forEachRemaining(k -> {
         System.out.println("Key: " + k);
        });
        
        map.values().iterator().forEachRemaining(v -> {
         System.out.println("Value: " + v);
        });
 }
}

Output

Using Collection.iterator() & Iterator.forEachRemaining()
Key: 1
Key: 2
Key: 3
Value: Java
Value: Spring MVC
Value: AngularJS

Print all keys and values in HashMap using Collection.stream() & Stream.forEach()

package com.jackrutorial;

import java.util.HashMap;

public class PrintingHashmapExample3 {

 public static void main(String[] args) {
  var map = new HashMap<>();
  map.put(1, "Java");
  map.put(2, "Spring MVC");
  map.put(3, "AngularJS");

  // Using Collection.stream() & Stream.forEach()
  System.out.println("Using Collection.stream() & Stream.forEach()");
  map.keySet().stream().forEach(k -> {
   System.out.println("Key: " + k);
  });

  map.values().stream().forEach(k -> {
   System.out.println("Key: " + k);
  });
 }
}

Output

Using Collection.stream() & Stream.forEach()
Key: 1
Key: 2
Key: 3
Key: Java
Key: Spring MVC
Key: AngularJS

Print all keys and values in HashMap using Stream.of() & Stream.forEach()

package com.jackrutorial;

import java.util.HashMap;
import java.util.stream.Stream;

public class PrintingHashmapExample4 {

 public static void main(String[] args) {
  var map = new HashMap<>();
  map.put(1, "Java");
  map.put(2, "Spring MVC");
  map.put(3, "AngularJS");

  // Using Stream.of() & Stream.forEach()
  System.out.println("Using Stream.of() & Stream.forEach()");
  Stream.of(map.keySet().toString()).forEach(k -> {
   System.out.println("Key: " + k);
  });

  Stream.of(map.values().toString()).forEach(v -> {
   System.out.println("Value: " + v);
  });
 }
}

Output

Using Stream.of() & Stream.forEach()
Key: [1, 2, 3]
Value: [Java, Spring MVC, AngularJS]

Print all keys and values in HashMap using Iterator

package com.jackrutorial;

import java.util.HashMap;

public class PrintingHashmapExample5 {

 public static void main(String[] args) {
  var map = new HashMap<>();
  map.put(1, "Java");
  map.put(2, "Spring MVC");
  map.put(3, "AngularJS");

  // Using Iterator
  System.out.println("Using Iterator");
  var keyItr = map.keySet().iterator();
  while (keyItr.hasNext()) {
   System.out.println("Key: " + keyItr.next());
  }
  
  var vItr = map.values().iterator();
  while (vItr.hasNext()) {
   System.out.println("Value: " + vItr.next());
  }
 }
}

Output

Using Iterator
Key: 1
Key: 2
Key: 3
Value: Java
Value: Spring MVC
Value: AngularJS
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