What is the getOrDefault function in Java HashMap?

The getOrDefault function in Java comes with the HashMap class, and is used to find the value of a corresponding key stored inside a HashMap object.

Syntax

default V getOrDefault(Object key, V defaultValue)

Parameters

The getOrDefault function takes in two parameters:

key: the key whose corresponding value is to be returned.
defaultValue: value to be returned by default in case the key prescribed by the user is not present in the HashMap object.

Return value

Upon successful execution, the getOrDefault function returns the corresponding value of the key prescribed by the user.

If the key is not present, the defaultValue is returned.

Example

The program below demonstrates how to use the getOrDefault function. We declare a HashMap object named countries, which stores the rank and name of the four largest countries (area wise) as key-value pairs.

Each country name is in lower case.

We use the getOrDefault function to find the country that ranks 3 and store the return value in a String variable named a. Since our HashMap stores information about the top 4 rankings only, when inquired for the country that ranks 5, the getOrDefault function returns the default value, as 5 is not a key in any of the key-value pairs. The default value is stored in a String value named b.

Before terminating, the program prints the values of a and b using the println function.

import java.util.HashMap;
class Main {
    public static void main(String[] args) {
        System.out.println("This program ranks countries on the basis of land-area covered.");
        System.out.println("Each key in the HashMap is a rank and each corresponding value is a country name.");
        
        // create an HashMap
        HashMap<Integer, String> countries = new HashMap<>();
        // populate the HashMap
        countries.put(1, "russia");
        countries.put(2, "canada");
        countries.put(3, "china");
        countries.put(4, "united states");
        System.out.println("**Printing HashMap**");
        System.out.println(countries);
        //Apply getOrDefault function
        String a = countries.getOrDefault(3, "No entry found!");
        String b = countries.getOrDefault(5, "No entry found!");
    
        System.out.println("The value returned for key = 3: " + a);
        System.out.println("The value returned for key = 5: "+ b);
    }
}

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