Properties keySet() method in Java with Examples

The keySet() method of Properties class is used to create a set out of the key elements contained in the Properties. It basically returns a set view of the keys or we can create a new set and store the key elements in them.

Syntax:

public Set keySet()

Parameters: This method accepts no parameters

Returns: This method returns a Set view of the keys contained in this Properties object.

Below programs show the implementation of int keySet() method.

Program 1:

// Java code to show the implementation of
// keySet() method

import java.util.*;
public class GfG {

    // Main method
    public static void main(String[] args)
    {

        // Create a properties and add some values
        Properties properties = new Properties();
        properties.put("Pen", 10);
        properties.put("Book", 500);
        properties.put("Clothes", 400);
        properties.put("Mobile", 5000);

        // Print Properties details
        System.out.println("Properties: "
                           + properties.toString());

        System.out.println("keySet: "
                           + properties.keySet());
    }
}

Output:

Properties: {Book=500, Mobile=5000, Pen=10, Clothes=400}
keySet: [Book, Mobile, Pen, Clothes]

Program 2:

// Java program to demonstrate
// keySet() method.

import java.util.*;

public class GFG {

    // Main method
    public static void main(String[] args)
    {

        // Create a properties and add some values
        Properties properties = new Properties();

        // Inserting elements into the properties
        properties.put("Geeks", 10);
        properties.put("4", 15);
        properties.put("Geeks", 20);
        properties.put("Welcomes", 25);
        properties.put("You", 30);

        // Print Properties details
        System.out.println("Current Properties: "
                           + properties.toString());

        System.out.println("keySet: "
                           + properties.keySet());
    }
}

Output:

Current Properties: {You=30, Welcomes=25, 4=15, Geeks=20}
keySet: [You, Welcomes, 4, Geeks]

References: https://docs.oracle.com/javase/9/docs/api/java/util/Properties.html#keySet–