What is the HashMap clear() method in Java?

// import the util lib from Java
import java.util.*;
class HelloWorld {
    public static void main( String args[] ) {
    {
		// Creating an empty HashMap based on our data
		HashMap<Integer, String> hash_map = new HashMap<Integer, String>();
		// Introduce some data in the hashmap
		hash_map.put(10, "Apple");
		hash_map.put(20, "Banana");
		hash_map.put(30, "Orange");
		// Lets have a look at the HashMap
		System.out.println("Hashmap: "+ hash_map);
		// apply the clear method to the hashmap
		hash_map.clear();
		// Lets have a look a look at the hashmap
		System.out.println("After applying clear method: " + hash_map);
	}
  }
}