Maps

The Map interface provides a way to map keys to values. This tutorial will teach you how to use maps in Java.

Creating a Map

To create a map, use the HashMap class:

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

public class Main {
    public static void main(String[] args) {
        Map<String, Integer> ages = new HashMap<>();
        ages.put("Alice", 25);
        ages.put("Bob", 30);
        ages.put("Charlie", 35);
        
        System.out.println(ages);
    }
}
      

Accessing Values in a Map

You can access values in a map using the get method:

public class Main {
    public static void main(String[] args) {
        Map<String, Integer> ages = new HashMap<>();
        ages.put("Alice", 25);
        ages.put("Bob", 30);
        ages.put("Charlie", 35);
        
        System.out.println(ages.get("Bob")); // Outputs: 30
    }
}
      

Removing Entries from a Map

Use the remove method to remove entries from a map:

public class Main {
    public static void main(String[] args) {
        Map<String, Integer> ages = new HashMap<>();
        ages.put("Alice", 25);
        ages.put("Bob", 30);
        ages.put("Charlie", 35);
        
        ages.remove("Bob");
        System.out.println(ages); // Outputs: {Alice=25, Charlie=35}
    }
}
      

Iterating Over a Map

You can iterate over a map using a for-each loop:

public class Main {
    public static void main(String[] args) {
        Map<String, Integer> ages = new HashMap<>();
        ages.put("Alice", 25);
        ages.put("Bob", 30);
        ages.put("Charlie", 35);
        
        for (Map.Entry<String, Integer> entry : ages.entrySet()) {
            System.out.println(entry.getKey() + ": " + entry.getValue());
        }
    }
}
      

Continue exploring our intermediate tutorials to learn more about Java programming.