How do I use a foreach loop with maps in Java?

How do I use a foreach loop with maps in Java?

You can use the forEach method in Java to iterate over a map. Here's an example:

Map<String, Integer> map = new HashMap<>();
map.put("A", 1);
map.put("B", 2);
map.forEach((key, value) -> {
    System.out.println(key + " : " + value);
});

This will print each key-value pair in the map.

Can you explain how the lambda expression works in that example?

Sure! The lambda expression (key, value) -> { System.out.println(key + " : " + value); } is a concise way to define the action to be performed for each entry in the map. Here, key and value are the parameters representing each entry's key and value.

What if I want to filter the entries before printing them?

You can use the entrySet() method along with a stream to filter entries. For example:

map.entrySet().stream()
    .filter(entry -> entry.getValue() > 1)
    .forEach(entry -> System.out.println(entry.getKey() + " : " + entry.getValue()));

This will print only the entries where the value is greater than 1.

Is there a way to use a traditional for loop instead?

Yes, you can use a traditional for loop by iterating over the key set of the map. Here's how:

for (String key : map.keySet()) {
    System.out.println(key + " : " + map.get(key));
}

This will achieve the same result as the foreach loop.