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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.
- Iterating over Map.entrySet() using For-Each loop : Map.entrySet()method returns a collection-view(Set >) of the mappings contained in this map.
- Iterating over keys or values using keySet() and values() methods. Map.keySet()method returns a Set view of the keys contained in this map and Map.values()method returns a collection-view of the values contained in this map.
- Iterating using iterators over Map.Entry This method is somewhat similar to first one. In first method we use for-each loop over Map.Entry , but here we use iterators.
- Using forEach(action) method : In Java 8, you can iterate a map using Map.forEach(action)method and using lambda expression. This technique is clean and fast.
Jan 8, 2024 · values () – returns the Set of all values in the map. Next, let’s see these methods in action. 3. Using for-each and entrySet () First, let’s see how to iterate through a Map using the entrySet () method: long sum = 0; for (Map.Entry<Integer, Integer> entry : map.entrySet()) {. sum += entry.getValue(); return sum;
- Using `Entryset()`
- Using `Foreach`
- Using `Stream
- Using `Keyset()` and `get()`
- References
Before Java 8, this is the most common method to loop a Map in Java. We use the map’s entry set entrySet()to loop and access to each key-value pair. output
Java 8 introduced the forEachmethod, which provides a more simple way to iterate over maps using lambda expressions. output
We can use stream()to loop, filtering and collect in Java 8. output In below example, we use stream() to get the map’s entry if it’s value is equals to Jan. output
This method involves iterating over the key set and then using each key to get its corresponding value. It’s slightly less efficient than using entrySet() because of the additional get()call. It might be useful for conditionally fetch values.
May 5, 2023 · Iterating over keys: In this method, we obtain the set of keys from the map using the keySet() method and iterate over the set using a for-each loop or an iterator. For each key in the set, we can ...
Sep 7, 2023 · In this post, I’ll introduce you to several methods for iterating through a Map in Java, along with code examples. 1. Using EntrySet: The most common way to iterate through a Map is by using the ...
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Oct 3, 2023 · Here’s how to effectively iterate through them: Convert to Entry Set: To iterate through an immutable map, convert it to an entry set and then use the entrySet () method as demonstrated earlier; Creating Streams: For Java 8 and later, you can use streams to iterate over immutable maps.
