Java — HashMap

Create HashMap

import java.util.HashMap;

HashMap<String, Integer> ages = new HashMap<>();

Add entries

ages.put("Alice", 25);
ages.put("Bob", 30);

Access values

int aliceAge = ages.get("Alice");
boolean hasAlice = ages.containsKey("Alice");

Remove entries

ages.remove("Bob");

Iterate

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

Mini Practice

1. Create HashMap
2. Add key-value pairs
3. Access values
4. Iterate through map

Up Next

Continue with HashSet - Unique elements.