Can someone help me understand how to use a copy constructor in JAVA to change any FINAL instance variable?

Problem:

public class Test{

public final int num;

public final int data;

//Constructor

public Test(int num, int data){

this.num= num;

this.data=data;

}

//Copy Constructor

public Test(Test copy){

this.num= copy.num;

this.data = copy.data;

}

// What if I only want to change the value of data to a given integer when creating a new Test object?