How to Check if a Value Exists in a Map in Java - Step by Step Examples

How to Check if a Value Exists in a Map in Java ?

Answer

To check if a value exists in a map in Java, you can use the containsValue method. This method returns a boolean value indicating whether the map contains the specified value.

✐ Examples

1 Checking if a Value Exists Using containsValue Method

We can check if a value exists in a map in Java using the containsValue method, which returns true if the map contains the specified value 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 a map named myMap with some key-value pairs. In this example, the map has integer keys and string values.
We use the containsValue method to check for a specific value in the map. The containsValue method returns a boolean value indicating whether the map contains the specified value.
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 a value exists using containsValue method
        boolean valueExists = myMap.containsValue("two");

        // Print the result
        System.out.println("Does value 'two' exist? " + valueExists);
    }
}

Output

Does value 'two' exist? true

2 Checking if a Value Does Not Exist Using containsValue Method

We can check if a value does not exist in a map in Java using the containsValue method, which returns false if the map does not contain the specified value.

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 containsValue method to check for a specific value in the map. The containsValue method returns a boolean value indicating whether the map contains the specified value.
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 a value does not exist using containsValue method
        boolean valueExists = myMap.containsValue("four");

        // Print the result
        System.out.println("Does value 'four' exist? " + valueExists);
    }
}

Output

Does value 'four' exist? false

3 Checking Multiple Values Using containsValue Method

We can check if multiple values exist in a map in Java using the containsValue method, which returns true if the map contains the specified value 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 a map named myMap with some key-value pairs. In this example, the map has integer keys and string values.
We use the containsValue method to check for multiple values in the map. The containsValue method returns a boolean value indicating whether the map contains the specified value.
We print the results 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 multiple values exist using containsValue method
        boolean valueExistsOne = myMap.containsValue("one");
        boolean valueExistsFour = myMap.containsValue("four");

        // Print the results
        System.out.println("Does value 'one' exist? " + valueExistsOne);
        System.out.println("Does value 'four' exist? " + valueExistsFour);
    }
}

Output

Does value 'one' exist? true
Does value 'four' exist? false

Summary

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

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How to Check if a Value Exists in a Map in Java - Step by Step Examples