How to Safely Remove Elements from a Map While Iterating?

Iterating Over and Removing Elements from a Map: An Improved Solution

When attempting to iterate over a map's keys and remove elements conditionally, you might encounter a ConcurrentModificationException. To address this, it's recommended to create a new collection from the map's key set and iterate over that instead. However, this approach can be inefficient and complex.

A more effective solution is to use the Iterator interface's remove() method. This allows you to directly modify the map while iterating over it. Here's an example:

Map<String, String> map = new HashMap<>();
map.put("test", "test123");
map.put("test2", "test456");

for (Iterator<Map.Entry<String, String>> it = map.entrySet().iterator(); it.hasNext(); ) {
    Map.Entry<String, String> entry = it.next();
    if (entry.getKey().equals("test")) {
        it.remove();
    }
}

This code sample illustrates how to use the Iterator in a for loop to remove an entry from the map. By leveraging the remove() method, you can efficiently update the map's contents while iterating over its entries. This approach eliminates the need for additional synchronization blocks, making it a cleaner and more efficient solution.

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