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hashmap.keySet()

import java.util.HashMap;

class Main {
    public static void main(String[] args) {
        // Create a HashMap
        HashMap&lt;Integer, String> sites = new HashMap<>();

        // Add some elements to the HashMap
        sites.put(1, "Google");
        sites.put(2, "tutorialpro");
        sites.put(3, "Taobao");
        System.out.println("sites HashMap: " + sites);

        // Return a Set view of all the keys
        System.out.println("Keys: " + sites.keySet());
    }
}

sites HashMap: {1=Google, 2=tutorialpro, 3=Taobao}
Keys: [1, 2, 3]

import java.util.HashMap;

class Main {
    public static void main(String[] args) {
        // Create a HashMap
        HashMap&lt;Integer, String> sites = new HashMap<>();

        // Add some elements to the HashMap
        sites.put(1, "Google");
        sites.put(2, "tutorialpro");
        sites.put(3, "Taobao");
        System.out.println("sites HashMap: " + sites);

        // Return a Set view of all the keys
        System.out.println("Keys: " + sites.keySet());
        // keySet() returns a Set view of all the keys
        // for-each loop accesses each key in the view
        for(int key: sites.keySet()) {
            // Print each key
            System.out.print(key + ", ");
        }
    }
}

sites HashMap: {1=Google, 2=tutorialpro, 3=Taobao}
Keys: [1, 2, 3]
1, 2, 3,