MyClass.java
 

public class MyClass {
  final int x = 10;
  final double PI = 3.14;

  public static void main(String[] args) {
    MyClass myObj = new MyClass();
    myObj.x = 50; // will generate an error
    myObj.PI = 25; // will generate an error
    System.out.println(myObj.x); 
  }
}
Result:
MyClass.java:7: error: cannot assign a value to final variable x
    myObj.x = 50;
         ^
MyClass.java:8: error: cannot assign a value to final variable PI
    myObj.PI = 25;
         ^ 2 errors