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Jul 13, 2023 · How to iterate any Map in Java. There are generally five ways of iterating over a Map in Java. In this article, we will discuss all of them and also look at their advantages and disadvantages. First of all, we cannot iterate a Map directly using iterators, because Map are not Collection.
Jan 8, 2024 · Overview. In this quick tutorial, we’ll look at the different ways of iterating through the entries of a Map in Java. Simply put, we can extract the contents of a Map using entrySet (), keySet (), or values (). Since these are all sets, similar iteration principles apply to all of them. Let’s have a closer look at a few of these. Further reading:
How to iterate Map in Java. In Java, iteration over Map can be done in various ways. Remember that we cannot iterate over map directly using iterators, because Map interface is not the part of Collection. All maps in Java implements Map interface. There are following types of maps in Java: HashMap; TreeMap; LinkedHashMap
Jul 1, 2009 · If you need only keys or values from the map, you can iterate over keySet or values instead of entrySet. System.out.println("Key = " + key); System.out.println("Value = " + value); This method gives a slight performance advantage over entrySet iteration (about 10% faster) and is more clean.
The official way to do this is to call map.entrySet(), which returns a set of Map.Entry, each of which contains a key and a value ( entry.getKey() and entry.getValue() ). In an idiosyncratic implementation, it might make some difference whether you use map.keySet(), map.entrySet() or something else.
Feb 25, 2009 · 2 Answers. Sorted by: 89. Assuming K is your key type and V is your value type: for (Map.Entry<K,V> entry : map.entrySet()) { K key = entry.getKey(); V value = entry.getValue(); // do stuff. } This version works with every Java version that supports generic (i.e. Java 5 and up).
Jul 19, 2022 · What are some common ways to iterate a Map in Java? Though there are many ways to traverse a map. However, we will focus on the most efficient and simple ways. The ForEach Loop method. The Iterators method. Please find the implementation of both methods below. Using the Foreach Loop method. Example. import java.util.Map; import java.util.HashMap;
Jul 22, 2019 · If you need to iterate over the elements in a Map in Java 8, this source code shows how to do it: Map<String, String> map = new HashMap<String, String>(); . map.put("first_name", "Alvin"); . map.put("last_name", "Alexander"); // java 8 . map.forEach((k,v)->System.out.println("key: " + k + ", value: " + v));
Nov 10, 2019 · Looping over a Map in Java. In this post, we look at four different ways we can iterate through a map in Java. As of Java 8, we can use the forEach method as well as the iterator class to loop over a map. How to Iterate Map Entries (Keys and Values)
May 24, 2019 · A Quick Guide to How To Iterate Map in Java. Iterating Through HashMap in Java 8 forEach(Stream API - Lamda Expression) With Example Programs and Explained in Different Ways.
