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This tutorial explains how to print HashMapan element in Java and also provides some sample code to understand the topic.

HashMapIt is Mapan implementation class of the interface and is used to collect elements into key and value pairs. We can use various methods to print its elements. For example, keySet()the print method, values()the print method, entrySet()the print method, the asList()print method, etc. Let's see some examples.

HashMapPrinting Elements in Java

HashMapThis is the simplest way to print in Java . Just HashMappass the reference of to println()the method and it will print the key-value pairs inside the curly braces. See the following example.

import java.util.HashMap;
import java.util.Map;

public class SimpleTesting {
  public static void main(String[] args) {
    Map<Integer, String> map = new HashMap<>();
    map.put(10, "Ten");
    map.put(100, "Hundred");
    map.put(1000, "Thousand");
    System.out.println(map);
  }
}

Output:

{100=Hundred, 1000=Thousand, 10=Ten}

Printing elements using keySet()method in JavaHashMap

We can use keySet()the method to get a set of keys and then foruse get()the method in a loop to get the values. get()The method returns the value associated with the passed key. See the following example.

import java.util.HashMap;
import java.util.Map;

public class SimpleTesting {
  public static void main(String[] args) {
    Map<Integer, String> map = new HashMap<>();
    map.put(10, "Ten");
    map.put(100, "Hundred");
    map.put(1000, "Thousand");
    for (Integer key : map.keySet()) {
      System.out.println(key + " = " + map.get(key));
    }
  }
}

Output:

100 = Hundred
1000 = Thousand
10 = Ten

Printing elements using forEach()method in JavaHashMap

From Java 8 onwards, we can use forEach()the print method to print the elements of a with the help of getKey()and getValue()print methods HashMap. getKey()The print method entrySetreturns a key from a and getValue()the print method returns the value associated with that key. See the following example.

import java.util.HashMap;
import java.util.Map;

public class SimpleTesting {
  public static void main(String[] args) {
    Map<Integer, String> map = new HashMap<>();
    map.put(10, "Ten");
    map.put(100, "Hundred");
    map.put(1000, "Thousand");
    map.entrySet().forEach(
        entry -> { System.out.println(entry.getKey() + " = " + entry.getValue()); });
  }
}

Using the Arrays.asList()Print HashMapelement in Java

We can use Arrays.asList()the method to print HashMapthe elements of . asList()The method returns HashMapthe list form of . See the following example.

import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;

public class SimpleTesting {
  public static void main(String[] args) {
    Map<Integer, String> map = new HashMap<>();
    map.put(10, "Ten");
    map.put(100, "Hundred");
    map.put(1000, "Thousand");
    System.out.println(Arrays.asList(map));
  }
}

Output:

[{100=Hundred, 1000=Thousand, 10=Ten}]

CollectionsPrinting HashMapan element in Java using the class

We can use Collections.singletonList()the static method to print HashMapthe elements of . singletonList()The method returns HashMapthe list representation of . See the following example.

import java.util.Collections;
import java.util.HashMap;
import java.util.Map;

public class SimpleTesting {
  public static void main(String[] args) {
    Map<Integer, String> map = new HashMap<>();
    map.put(10, "Ten");
    map.put(100, "Hundred");
    map.put(1000, "Thousand");
    System.out.println(Collections.singletonList(map));
  }
}

Output:

[{100=Hundred, 1000=Thousand, 10=Ten}]

Printing elements using entrySet()method in JavaHashMap

entrySet()The method returns a set of items that can be used in a for loop to print HashMapelements. See the following example.

import java.util.HashMap;
import java.util.Map;

public class SimpleTesting {
  public static void main(String[] args) {
    Map<Integer, String> map = new HashMap<>();
    map.put(10, "Ten");
    map.put(100, "Hundred");
    map.put(1000, "Thousand");
    for (Map.Entry<Integer, String> entry : map.entrySet()) {
      System.out.println(entry.getKey() + " = " + entry.getValue());
    }
  }
}

Output:

100 = Hundred
1000 = Thousand
10 = Ten

Printing elements using values()and keySet()methods in JavaHashMap

If we want to print the values ​​and keys separately, we can use the values()and keySet()methods. values()The method returns a list of all values, while keySet()the method returns a list of all HashMapkeys. See the following example.

import java.util.HashMap;
import java.util.Map;

public class SimpleTesting {
  public static void main(String[] args) {
    Map<Integer, String> map = new HashMap<>();
    map.put(10, "Ten");
    map.put(100, "Hundred");
    map.put(1000, "Thousand");
    System.out.println(map.values());
    System.out.println(map.keySet());
  }
}

Output:

[Hundred, Thousand, Ten]
[100, 1000, 10]

Using the BiconsumerPrint HashMapelement in Java

BiconsumerIs an interface in Java that can be used to lambdaprint HashMapan element using an expression. See the following example.

import java.util.HashMap;
import java.util.Map;
import java.util.function.BiConsumer;

public class SimpleTesting {
  public static void main(String[] args) {
    Map<Integer, String> map = new HashMap<>();
    map.put(10, "Ten");
    map.put(100, "Hundred");
    map.put(1000, "Thousand");
    BiConsumer<Integer, String> biconsumer = (key, val) -> System.out.println(key + " = " + val);
    map.forEach(biconsumer);
  }
}

Output:

100 = Hundred
1000 = Thousand
10 = Ten