Initialize a static Map using Stream in Java

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In this article, a static map is created and initialized in Java using Stream.

Static Map in Java
A static map is a map which is defined as static. It means that the map becomes a class member and can be easily used using class.

Stream In Java
Introduced in Java 8, the Stream API is used to process collections of objects. A stream is a sequence of objects that supports various methods which can be pipelined to produce the desired result.

Approach:

Create a stream and insert 2D values as Key and Value pair in it.
These values will be later used to instantiate the Map.
Using the collect() method of Stream, map the values from the stream to the map.
This can be done with the help of Collectors.toMap() method and the keyMapper and ValueMapper respectively.

Below is the implementation of the above approach:

// Java program to create a static map using Stream
  
import java.util.*;
import java.util.stream.Collectors;
  
class GFG {
  
    // Declaring and instantiating the static map
    private static Map<String, String> map
        = Arrays.stream(new String[][] {
                            { "1", "GFG" },
                            { "2", "Geek" },
                            { "3", "GeeksForGeeks" } })
              .collect(Collectors.toMap(
                  keyMapper -> keyMapper[0], valueMapper -> valueMapper[1]));
  
    // Driver code
    public static void main(String[] args)
    {
        System.out.println(map);
    }
}