How to Check if a Map is Empty in Java - Step by Step Examples

How to Check if a Map is Empty in Java ?

Answer

To check if a map is empty in Java, you can use the isEmpty method. This method returns a boolean value indicating whether the map contains any elements.

✐ Examples

1 Checking if a Map is Empty Using isEmpty Method

We can check if a map is empty in Java using the isEmpty method, which returns true if the map contains no elements and false otherwise.

For example,

We start by importing the java.util.HashMap package, which provides the HashMap class needed to create and manipulate the map.
We declare and initialize an empty map named myMap. In this example, the map has integer keys and string values.
We use the isEmpty method to check if the map is empty. The isEmpty method returns a boolean value indicating whether the map contains any elements.
We print the result to the console using System.out.println.

Java Program

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

public class Main {
    public static void main(String[] args) {
        // Declare and initialize an empty map
        Map<Integer, String> myMap = new HashMap<>();

        // Check if the map is empty using isEmpty method
        boolean isEmpty = myMap.isEmpty();

        // Print the result
        System.out.println("Is the map empty? " + (isEmpty ? "Yes" : "No"));
    }
}

Output

Is the map empty? Yes

2 Checking if a Non-Empty Map is Empty Using isEmpty Method

We can check if a non-empty map is empty in Java using the isEmpty method, which returns false if the map contains elements.

For example,

We start by importing the java.util.HashMap package, which provides the HashMap class needed to create and manipulate the map.
We declare and initialize a map named myMap with some key-value pairs. In this example, the map has integer keys and string values.
We use the isEmpty method to check if the map is empty. The isEmpty method returns a boolean value indicating whether the map contains any elements.
We print the result to the console using System.out.println.

Java Program

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

public class Main {
    public static void main(String[] args) {
        // Declare and initialize a map
        Map<Integer, String> myMap = new HashMap<>();
        myMap.put(1, "one");
        myMap.put(2, "two");
        myMap.put(3, "three");

        // Check if the map is empty using isEmpty method
        boolean isEmpty = myMap.isEmpty();

        // Print the result
        System.out.println("Is the map empty? " + (isEmpty ? "Yes" : "No"));
    }
}

Output

Is the map empty? No

3 Checking if a Map is Empty After Clearing Using isEmpty Method

We can check if a map is empty in Java after clearing its elements using the isEmpty method, which returns true if the map contains no elements.

For example,

We start by importing the java.util.HashMap package, which provides the HashMap class needed to create and manipulate the map.
We declare and initialize a map named myMap with some key-value pairs. In this example, the map has integer keys and string values.
We use the clear method to remove all elements from the map, making it empty.
We use the isEmpty method to check if the map is empty after clearing. The isEmpty method returns a boolean value indicating whether the map contains any elements.
We print the result to the console using System.out.println.

Java Program

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

public class Main {
    public static void main(String[] args) {
        // Declare and initialize a map
        Map<Integer, String> myMap = new HashMap<>();
        myMap.put(1, "one");
        myMap.put(2, "two");
        myMap.put(3, "three");

        // Clear the map
        myMap.clear();

        // Check if the map is empty using isEmpty method
        boolean isEmpty = myMap.isEmpty();

        // Print the result
        System.out.println("Is the map empty? " + (isEmpty ? "Yes" : "No"));
    }
}

Output

Is the map empty? Yes

Summary

In this tutorial, we learned How to Check if a Map is Empty in Java language with well detailed examples.

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How to Check if a Map is Empty in Java - Step by Step Examples