In this example, we filter a map by its keys.

Java Stream filter map by keys example

Tise example filters domain names starting with s letter.

import java.util.HashMap;
import java.util.Map;

public class JavaStreamFilterMapByKeys {

    public static void main(String[] args) {

        Map<String, String> hmap = new HashMap<>();
        
        hmap.put("de", "Germany");
        hmap.put("hu", "Hungary");
        hmap.put("sk", "Slovakia");
        hmap.put("si", "Slovenia");
        hmap.put("so", "Somalia");
        hmap.put("us", "United States");
        hmap.put("ru", "Russia");
        
        hmap.entrySet().stream().filter(map -> map.getKey().startsWith("s"))
                .forEach(m -> System.out.println(m));
    }
}

Output:

si=Slovenia
sk=Slovakia
so=Somalia

This is the output of the example.

Related HashMap Source Code Examples

• Create a HashMap in Java Example

• Check If Key Exists in HashMap Java Example

• Iterate over HashMap in Java

• How to Store Employee Objects in HashMap

• Remove Entry from HashMap Java

• Check If Value Exists in HashMap Java Example

• HashMap Stream and Filtering Example

• Java HashMap Iteration over Values Example

• Java HashMap Iteration over Keys

• Java HashMap replace() Example

• Java HashMap size Example

• Iterate over a HashMap Java using Lambda

• Iterate over a HashMap Java 8 forEach

• Iterating over a HashMap using Iterator in Java