Map<String, String> map = ...
for (Map.Entry<String, String> entry : map.entrySet()) {
System.out.println(entry.getKey() + "/" + entry.getValue());
}
On Java 10+:
for (var entry : map.entrySet()) {
System.out.println(entry.getKey() + "/" + entry.getValue());
}
Top answer 1 of 16
5965
Map<String, String> map = ...
for (Map.Entry<String, String> entry : map.entrySet()) {
System.out.println(entry.getKey() + "/" + entry.getValue());
}
On Java 10+:
for (var entry : map.entrySet()) {
System.out.println(entry.getKey() + "/" + entry.getValue());
}
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To summarize the other answers and combine them with what I know, I found 10 main ways to do this (see below). Also, I wrote some performance tests (see results below). For example, if we want to find the sum of all of the keys and values of a map, we can write:
Using iterator and Map.Entry
long i = 0; Iterator<Map.Entry<Integer, Integer>> it = map.entrySet().iterator(); while (it.hasNext()) { Map.Entry<Integer, Integer> pair = it.next(); i += pair.getKey() + pair.getValue(); }Using foreach and Map.Entry
long i = 0; for (Map.Entry<Integer, Integer> pair : map.entrySet()) { i += pair.getKey() + pair.getValue(); }Using forEach from Java 8
final long[] i = {0}; map.forEach((k, v) -> i[0] += k + v);Using keySet and foreach
long i = 0; for (Integer key : map.keySet()) { i += key + map.get(key); }Using keySet and iterator
long i = 0; Iterator<Integer> itr2 = map.keySet().iterator(); while (itr2.hasNext()) { Integer key = itr2.next(); i += key + map.get(key); }Using for and Map.Entry
long i = 0; for (Iterator<Map.Entry<Integer, Integer>> entries = map.entrySet().iterator(); entries.hasNext(); ) { Map.Entry<Integer, Integer> entry = entries.next(); i += entry.getKey() + entry.getValue(); }Using the Java 8 Stream API
final long[] i = {0}; map.entrySet().stream().forEach(e -> i[0] += e.getKey() + e.getValue());Using the Java 8 Stream API parallel
final long[] i = {0}; map.entrySet().stream().parallel().forEach(e -> i[0] += e.getKey() + e.getValue());Using IterableMap of
Apache Collectionslong i = 0; MapIterator<Integer, Integer> it = iterableMap.mapIterator(); while (it.hasNext()) { i += it.next() + it.getValue(); }Using MutableMap of Eclipse (CS) collections
final long[] i = {0}; mutableMap.forEachKeyValue((key, value) -> { i[0] += key + value; });
Perfomance tests (mode = AverageTime, system = Windows 8.1 64-bit, Intel i7-4790 3.60 GHz, 16 GB)
For a small map (100 elements), score 0.308 is the best
Benchmark Mode Cnt Score Error Units test3_UsingForEachAndJava8 avgt 10 0.308 ± 0.021 µs/op test10_UsingEclipseMap avgt 10 0.309 ± 0.009 µs/op test1_UsingWhileAndMapEntry avgt 10 0.380 ± 0.014 µs/op test6_UsingForAndIterator avgt 10 0.387 ± 0.016 µs/op test2_UsingForEachAndMapEntry avgt 10 0.391 ± 0.023 µs/op test7_UsingJava8StreamApi avgt 10 0.510 ± 0.014 µs/op test9_UsingApacheIterableMap avgt 10 0.524 ± 0.008 µs/op test4_UsingKeySetAndForEach avgt 10 0.816 ± 0.026 µs/op test5_UsingKeySetAndIterator avgt 10 0.863 ± 0.025 µs/op test8_UsingJava8StreamApiParallel avgt 10 5.552 ± 0.185 µs/opFor a map with 10000 elements, score 37.606 is the best
Benchmark Mode Cnt Score Error Units test10_UsingEclipseMap avgt 10 37.606 ± 0.790 µs/op test3_UsingForEachAndJava8 avgt 10 50.368 ± 0.887 µs/op test6_UsingForAndIterator avgt 10 50.332 ± 0.507 µs/op test2_UsingForEachAndMapEntry avgt 10 51.406 ± 1.032 µs/op test1_UsingWhileAndMapEntry avgt 10 52.538 ± 2.431 µs/op test7_UsingJava8StreamApi avgt 10 54.464 ± 0.712 µs/op test4_UsingKeySetAndForEach avgt 10 79.016 ± 25.345 µs/op test5_UsingKeySetAndIterator avgt 10 91.105 ± 10.220 µs/op test8_UsingJava8StreamApiParallel avgt 10 112.511 ± 0.365 µs/op test9_UsingApacheIterableMap avgt 10 125.714 ± 1.935 µs/opFor a map with 100000 elements, score 1184.767 is the best
Benchmark Mode Cnt Score Error Units test1_UsingWhileAndMapEntry avgt 10 1184.767 ± 332.968 µs/op test10_UsingEclipseMap avgt 10 1191.735 ± 304.273 µs/op test2_UsingForEachAndMapEntry avgt 10 1205.815 ± 366.043 µs/op test6_UsingForAndIterator avgt 10 1206.873 ± 367.272 µs/op test8_UsingJava8StreamApiParallel avgt 10 1485.895 ± 233.143 µs/op test5_UsingKeySetAndIterator avgt 10 1540.281 ± 357.497 µs/op test4_UsingKeySetAndForEach avgt 10 1593.342 ± 294.417 µs/op test3_UsingForEachAndJava8 avgt 10 1666.296 ± 126.443 µs/op test7_UsingJava8StreamApi avgt 10 1706.676 ± 436.867 µs/op test9_UsingApacheIterableMap avgt 10 3289.866 ± 1445.564 µs/op
Graphs (performance tests depending on map size)
Table (perfomance tests depending on map size)
100 600 1100 1600 2100
test10 0.333 1.631 2.752 5.937 8.024
test3 0.309 1.971 4.147 8.147 10.473
test6 0.372 2.190 4.470 8.322 10.531
test1 0.405 2.237 4.616 8.645 10.707
test2 0.376 2.267 4.809 8.403 10.910
test7 0.473 2.448 5.668 9.790 12.125
test9 0.565 2.830 5.952 13.220 16.965
test4 0.808 5.012 8.813 13.939 17.407
test5 0.810 5.104 8.533 14.064 17.422
test8 5.173 12.499 17.351 24.671 30.403
All tests are on GitHub.
Naukri
naukri.com › code360 › library › iterate-map-in-java
How to Iterate Map in Java? - Naukri Code 360
Almost there... just a few more seconds
java - Iterate through a HashMap - Stack Overflow
This method might look redundant, but it has its own advantages. First of all, it is the only way to iterate over a map in older versions of Java. The other important feature is that it is the only method that allows you to remove entries from the map during iteration by calling iterator.remove(). More on stackoverflow.com
How To Iterate Over Hashmap In A For-Loop Context?
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8
1
July 20, 2023Iterate through hashmap using the classic for-loop
I suppose you could fetch the iterator of the entry set of the hashmap, and use that, but that seems a bit silly and basically ignores the index anyway. The reason you haven't found any examples is because a tradional for loop is mostly used when you need the index, but a HashMap isn't ordered so the index is meaningless. Iterator> iterator = myHashMap.entrySet().iterator(); for (;iterator.hasNext();) { Map.Entry myEntry = iterator.next(); } or even Iterator> iterator = myHashMap.entrySet().iterator(); int size = myHashMap.size(); for (int i = 0; i < size; i++) { Map.Entry myEntry = iterator.next(); } Though I really wouldn't use the last one. Using iterator.next() without first checking iterator.hasNext() is not really the correct way to use an iterator. More on reddit.com
6
1
January 18, 2022Unable to iterate through HashMap in Java using forEach and entrySet().
Maybe you don't understand how the hash map works. A key is always unique. In the test case, which seems to be: 0 1 2 0 3 4 5 2 1 3 1 5 You first add the first element to hashmap, key: 0 and value: 0. Then you iterate and find the another zero on the first row. Now you add to hashmap, key: 0, value: 3. You are using the i-coordinate as the key. Of course in this example there are two 0's on the same row. Only one of these can be saved on the hash map. I have no idea how the hashmap would be of any use in this problem anyway. You want to store coordinates, right? Can you not create a class Point or something and store them on a list? More on reddit.com
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4
January 23, 2025Videos
11:27
5 Best Ways to Iterate Over HashMap in Java - YouTube
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#8 - What is HashMap? How to iterate HashMap?
CodeGym
codegym.cc › java blog › java collections › how to iterate a map in java
How to iterate a Map in Java
January 8, 2025 - User the iterator if you have to modify the map. Use the for-each loop if you have nested loops (to avoid complexity). The Stream API, introduced in Java 8, offers a functional and concise way to iterate over a Map.
Java Code Geeks
javacodegeeks.com › home › core java
Exploring Different Techniques to Iterate a List of Maps in Java - Java Code Geeks
July 1, 2024 - This article explores some of the most common methods, providing a look at their implementation. This approach uses nested loops to iterate through the list of maps and then through each map’s key-value pairs using the entrySet() method.
GeeksforGeeks
geeksforgeeks.org › java › iterate-map-java
How to Iterate Any Map in Java? - GeeksforGeeks
July 23, 2025 - There are 5 ways to iterate over the elements of a map, and in this article, we are going to discuss all of them.
Edureka
edureka.co › blog › iterate-maps-java
How to Iterate Maps in Java | 5 Different Ways to Iterate Map | Edureka
June 17, 2021 - The Java Map interface, java.util.Map, represents the mapping between a key and a value i.e. a Java Map can store pairs of keys and values where each key is linked to a specific value. Once stored in a Map, you can later look up a particular value by using just the key of assigned to that value. Each key can be mapped to at most one value. We cannot iterate a Map directly using iterators, because Map is not Collection so we use some other ways to iterate Maps which are described in detail further in this blog.
Baeldung
baeldung.com › home › java › java collections › java map › iterate over a map in java
Iterate Over a Map in Java | Baeldung
December 16, 2024 - We create a MapIterator object, ... object to it. We then invoke the mapIterator() method on the IterableMap object to obtain a MapIterator type. Let’s compare the performance of the various options of iterating over a map using the Java Microbench Harness ...
Sentry
sentry.io › sentry answers › java › how to iterate over a hashmap in java
How to Iterate Over a HashMap in Java | Sentry
Perhaps the most straightforward approach to iterating over a HashMap is to use a for-each loop to iterate over each entry. Using the HashMap.entrySet() will return a set view of the mappings or entries in the HashMap. import java.util.HashMap; ...
Medium
medium.com › @reetesh043 › mastering-map-iteration-in-java-a-comprehensive-guide-f64f12115d36
How To Iterate Map in Java. Introduction | by Reetesh Kumar | Medium
January 25, 2024 - The for-each() loop is a simple and convenient way to iterate through a map.
Scaler
scaler.com › home › topics › how to iterate any map in java
How to Iterate Any Map in Java - Scaler Topics
March 14, 2024 - In Java, Maps cannot be iterated directly using iterators since they are not Collections. There are mainly five ways to iterate over a Map in Java. This article explores each method, discussing their pros and cons. Before delving into the different methods, It is important to understand the Map.Entry<K, V> interface.
DevQA
devqa.io › java-iterate-list-of-maps
How to Iterate a List of Maps in Java
You can then iterate through this set, and for each key, fetch the corresponding value using the get() method. for (Map<String, Object> map : listOfMaps) { for (String key : map.keySet()) { Object value = map.get(key); System.out.format("%s: ...
freeCodeCamp
freecodecamp.org › news › java-iterator-hashmap-how-to-iterate-through-a-hashmap-with-a-loop
Java Iterator Hashmap – How to Iterate Through a Hashmap With a Loop
May 5, 2023 - Firstly, you initiate the hashmap, use an iterator to iterate through the hashmap, and finally display your output. One of the simplest ways to iterate through a hashmap is by using a for-each loop.
Interview Kickstart
interviewkickstart.com › home › blogs › learn › how to iterate a map in java
How to Iterate a Map in Java | Interview Kickstart
September 25, 2024 - In Java, a group of objects that can be represented as a single unit is a collection of objects. We can iterate on collections using iterators. As Maps are not a collection, we cannot iterate on them using iterators. We have to employ other methods to iterate through a Map.
Top answer 1 of 7
5420
If you're only interested in the keys, you can iterate through the keySet() of the map:
Map<String, Object> map = ...;
for (String key : map.keySet()) {
// ...
}
If you only need the values, use values():
for (Object value : map.values()) {
// ...
}
Finally, if you want both the key and value, use entrySet():
for (Map.Entry<String, Object> entry : map.entrySet()) {
String key = entry.getKey();
Object value = entry.getValue();
// ...
}
One caveat: if you want to remove items mid-iteration, you'll need to do so via an Iterator (see karim79's answer). However, changing item values is OK (see Map.Entry).
2 of 7
3458
Iterate through the entrySet() like so:
public static void printMap(Map mp) {
Iterator it = mp.entrySet().iterator();
while (it.hasNext()) {
Map.Entry pair = (Map.Entry)it.next();
System.out.println(pair.getKey() + " = " + pair.getValue());
it.remove(); // avoids a ConcurrentModificationException
}
}
Read more about Map.
Programiz
programiz.com › java-programming › examples › iterate-over-hashmap
Java Program to Iterate over a HashMap
import java.util.HashMap; import java.util.Map.Entry; class Main { public static void main(String[] args) { // Creating a HashMap HashMap<String, String> languages = new HashMap<>(); languages.put("Java", "Enterprise"); languages.put("Python", "ML/AI"); languages.put("JavaScript", "Frontend"); System.out.println("HashMap: " + languages); // iterating through key/value mappings System.out.print("Entries: "); for(Entry<String, String> entry: languages.entrySet()) { System.out.print(entry); System.out.print(", "); } // iterating through keys System.out.print("\nKeys: "); for(String key: languages.keySet()) { System.out.print(key); System.out.print(", "); } // iterating through values System.out.print("\nValues: "); for(String value: languages.values()) { System.out.print(value); System.out.print(", "); } } }
Reddit
reddit.com › r/javaexamples › 4 ways to iterate over map in java
r/javaexamples on Reddit: 4 ways to iterate over Map in Java
September 4, 2024 - I wrote an article about iterating over a Map in Java - https://javarevisited.blogspot.com/2011/12/how-to-traverse-or-loop-hashmap-in-java.html Share
Mkyong
mkyong.com › home › java › how to loop map in java
How to loop Map in Java - Mkyong.com
March 13, 2024 - package com.mkyong.examples; import java.util.HashMap; import java.util.Iterator; import java.util.Map; public class LoopMap4 { public static void main(String[] args) { Map<Integer, String> map = new HashMap<>(); map.put(1, "Jan"); map.put(2, "Feb"); map.put(3, "Mar"); // Map -> Set -> Iterator -> Map.Entry Iterator<Map.Entry<Integer, String>> iterator = map.entrySet().iterator(); while (iterator.hasNext()) { Map.Entry<Integer, String> entry = iterator.next(); System.out.println("Key : " + entry.getKey() + " Value :" + entry.getValue()); } } } This method involves iterating over the key set an
Academic Help
academichelp.net › coding › java › how-to-iterate-map.html
How to Iterate Map in Java: Mastering Efficient Map Iteration
December 26, 2023 - Method 2 using entrySet is generally faster than Method 1 using keySet, especially for large maps. Method 3 using forEach provides a modern and concise approach but may have slightly more overhead compared to Method 2. Iterating over a map in Java is a fundamental skill for every Java developer.
Xperti
xperti.io › home › how to iterate over a map in java
How To Iterate Over a Map In Java
September 13, 2023 - The iterator is an interface used to iterate over a collection. As we can view maps as a collection, they can also be iterated via the iterator. The iterator interface is also an alternate for Enumeration in Java Collections Framework.
SourceBae
sourcebae.com › home › how do i efficiently iterate over each entry in a java map?
How do I efficiently iterate over each entry in a Java Map? - SourceBae
August 21, 2025 - The entrySet iterator can sometimes ... iterations. Another widely popular technique for iterating over a Java Map is using the keySet() method....