Why final instance class variable in Java?

Question

If instance variable is set final its value can not be changed like

public class Final {

    private final int b;

    Final(int b) {
        this.b = b; 
         


        

Answer 1

It means that the hasmap cannot be changed. The elements inside the hashmap are not tied to the final delimiter.

private static final HashMap map = new HashMap();

public void foo(K k, V v) {
    map.push(k, v);  //This is allowed
    map = new HashMap  //This is not allowed
}