Как распечатать map java
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Как распечатать map java

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How to Print a Map in Java

This write-up will specifically demonstrate the method of printing a map in Java.

How to Print a Map in Java?

To print a map in Java, you can use:

  • for-each loop
  • Iterator

We will now check out each of the above-mentioned methods one by one.

Method 1: Print Map in Java Using for-each Loop

Within the for-each loop, you can use Map’s getValue() and getKey() methods to iterate over key-value pairs. This is the most systematic way to print a map and should be used if it is required to print both map keys and values.

To understand the concept, look at the example presented below.

First, we will create a map object named “newMap” and specify “Integer” and “String” as the Key-value pair, which indicates the key is of Integer type and the value is of String type:

Next, we will add the following three key-value pair in the Map object by using the “put()” method:

To print the created map object, we will utilize the “for-each” loop and invoke the “getKey()” and “getValue()” methods to retrieve the keys and their respective values:


Let’s head towards the second method!

Method 2: Print Map in Java Using an Iterator

As map does not extend the Collection interface, that’s why it lacks its own iterator. However, “Map.entrySet()” returns a set of key-value pairs, and this method extends the Collection interface, which can be utilized for iteration.

Here, we will use the same Map object created in the above example. Now, we will create the Iterator object named “itr”, which will contain the key-value pairs of the map object retrieved after the iteration. Lastly, we will utilize the “while” loop to print the Map object key-value pair on console:


We presented the basic information related for printing map in Java.


Java allows us to print a map using an iterator method or a for-each loop. The most commonly used method to print the Map in Java is the for-each loop as it iterates through key-value pairs by using the getKey() and getValue() methods of Map. The iterator method is almost the same for each loop but uses the iterator of the entrySet() method. This write-up showed you how to print a Map using Java.

About the author

Farah Batool

I completed my master’s degree in computer science. I am an academic researcher and love to learn and write about new technologies. I am passionate about writing and sharing my experience with the world.

Распечатайте все ключи и значения с карты в Java

В этом посте будут обсуждаться различные методы вывода всех ключей и значений из карты в Java.


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Мы знаем, что keySet() метод возвращает установленное представление ключей, содержащихся в карте, и values() метод возвращает установленное представление значений, содержащихся в карте. Итак, мы можем использовать keySet() распечатать все ключи, присутствующие на карте, и values() для печати всех значений. Есть несколько способов сделать это:

1. Использование Iterator

Map не имеет собственного итератора, поскольку он не расширяет Collection интерфейс. Оба keySet() а также values() возвращает набор, а набор расширяет Collection интерфейс, мы можем получить итератор.

2. Для каждого цикла

Цикл For-each доступен для любого объекта, реализующего Iterable интерфейс. В качестве Set расширяет Iterable интерфейс, мы можем использовать цикл for-each для перебора набора ключей и значений.

3. Java 8 — Iterator.forEachRemaining()

The Iterator интерфейс обеспечивает forEachRemaining() метод, который может печатать каждый элемент, пока все элементы не будут обработаны.

4. Java 8 – Stream.forEach()

Мы можем использовать цикл по набору ключей и значениям, используя Stream.forEach() метод для печати каждого элемента потока.

5. Использование toString()

Для отображения всех ключей или значений, присутствующих на карте, мы можем просто напечатать строковое представление keySet() а также values() , соответственно.

Ниже приведена простая программа на Java, которая печатает все ключи карты, используя keySet() в Java:

How To Print HashMap In Java [Keys And Values]

Do you want to know how to print HashMap values and keys in JAVA? In this post, I’ll show you how to print the hash map’s values and keys in JAVA.

HashMap is an implementation of the Map interface that is used to group elements into key-value pairs. We can use a variety of methods to print its elements. Examples include keySet(), values(), entrySet(), and asList(). Let us look at some examples.

Ways to Print Values and Keys in JAVA for HashMap

As you may be aware, the keySet() method returns a set view of the map’s keys, while the values() method returns a set view of the map’s values.

As a result, we can use keySet() to print all keys in the map and values() to print all values. There are numerous ways to accomplish this.

To get a set of keys, we can use the keySet() function, and then in the for loop, we can use the get() method to get the value. The get() function returns the value associated with the provided key. Examine the example below.

Using Println function to Print HashMap in JAVA

Using this method is the simplest way to print HashMap in Java. Simply pass the HashMap reference to the println() method, and the key-value pairs will be printed inside the curly braces. Take a look at the example below.


Printing HashMap Values and Keys in JAVA

Using for-each loop To Print HashMap In Java

The for-each loop can be used by any object that implements the Iterable interface. Because Set extends Iterable, we can use a for-each loop to loop through the keySet and values.


Using Iterator in Java 8 forEachRemaining()

The Iterator interface’s forEachRemaining() method can print each element until all of them have been processed.


Using Stream.forEach in Java 8

To print each stream element, we can use the Stream.forEach() method to loop through the keySet and values.


Using toString method ()

To display all keys and values on the map, we can simply print the string representations of keySet() and values().


Using Simple Iterator

Map does not have its own iterator because it does not extend the Collection interface. Because the set extends the Collection interface, we can get an iterator from both keySet() and values().


Wrap Up

I hope you now have a better understanding of how to print a hashmap in Java. I’ve provided more than five methods that you can use to print the keys and values of a HashMap in Java, which you can find in the code below.

Please follow us on Facebook and Twitter. Let us know the questions and answer you want to cover in this blog. Wanna read more interview-related questions? Check Other Post Related to Data Structures.

Java Print HashMap Example

This example shows how to print HashMap in Java. The example also shows how to print all keys, all values, and all key-value pairs of HashMap using different ways.

How to print HashMap in Java?

The AbstractMap class, the parent class of the HashMap class, has overridden the toString method which returns a string representation of the map. All key-value pairs are enclosed in < and >and separated by a comma (,). The iterator of the entry set returns the order of the key-value pairs.

How to print all keys and values of HashMap using entrySet?

If you do not want the default formatting done by the toString method, you can get the entry set from the HashMap and print all key-value pairs one by one using the for loop as given below.

Java 8 and above

If you are using Java version 8 and above, you can use the below given code to print all keys and values of HashMap.

How to print all the keys of HashMap?

The keySet method of the HashMap class returns a Set view containing all the keys of the HashMap.

You can also use the System.out.println statement instead of using the for loop if you do not want to change the output format.

How to print all the values of the HashMap?

The values method of the HashMap returns a Collection view containing all the values contained in the HashMap.

You can also use System.out.println statement instead of using the for loop if you do not want to change the output format.

How to print HashMap containing custom class object as keys or values?

In all of the above examples, we printed Integer and String objects using the System.out.println statement. They were printed fine because both of these classes have overridden the toString method. Let’s try to print HashMap containing custom class objects.

We have put objects of Emp class as values in the HashMap in below given example.

As you can see from the output, the keys were printed fine but the values were not. It is because our Emp class has not overridden the toString method so it inherited the method from the Object class.

The toString method of the Object class returns the class name of the object, followed by @, followed by the hexadecimal hash code of the object. The format is not readable and hence it is suggested for all the subclasses to override the toString method to produce informative text.

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