How to Get the Value Associated with a Key in a Map in Java - Step by Step Examples

How to Get the Value Associated with a Key in a Map in Java ?

Answer

To get the value associated with a key in a map in Java, you can use the get method. This method allows you to access the value directly using the key.

✐ Examples

1 Getting the Value Associated with a Key Using get Method

We can get the value associated with a key in a map in Java using the get method, which returns the value associated with the specified key.

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 get method to access the value associated with the key 2. The get method returns the value associated with the specified key.
We store the value in a variable named value.
We print the value 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");

        // Get the value associated with a key using get method
        String value = myMap.get(2);

        // Print the value
        System.out.println("The value associated with key 2 is: " + value);
    }
}

Output

The value associated with key 2 is: two

2 Handling Key Not Found Using get Method

We can handle the case where a key is not found in a map in Java using the get method, which returns null if the key is not present.

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 get method to attempt to access the value associated with the key 4. The get method returns null if the key is not found.
We store the value in a variable named value.
We check if the value is null and print an appropriate message 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");

        // Attempt to get the value associated with a non-existent key
        String value = myMap.get(4);

        // Print the result
        if (value == null) {
            System.out.println("Key 4 not found in the map.");
        } else {
            System.out.println("The value associated with key 4 is: " + value);
        }
    }
}

Output

Key 4 not found in the map.

3 Getting Multiple Values Using get Method

We can get multiple values associated with keys in a map in Java using the get method, which returns the value associated with each key.

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 get method to access the values associated with the keys 1 and 4. The get method returns the value associated with each key.
We store the values in variables named valueOne and valueFour.
We print the values to the console using System.out.println. If a key is not found, the corresponding value will be null.

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");

        // Get the values associated with keys 1 and 4 using get method
        String valueOne = myMap.get(1);
        String valueFour = myMap.get(4);

        // Print the values
        System.out.println("The value associated with key 1 is: " + valueOne);
        System.out.println("The value associated with key 4 is: " + valueFour);
    }
}

Output

The value associated with key 1 is: one
The value associated with key 4 is: null

Summary

In this tutorial, we learned How to Get the Value Associated with a Key in a Map in Java language with well detailed examples.

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How to Get the Value Associated with a Key in a Map in Java - Step by Step Examples