/*
  Author:  James Tam
  Version: Feb. 4, 2021

  Learning objective: Deep vs. shallow copy of 
  arrays of 'objects': a more complex example 
  with a subtle problem.
*/
public class Driver
{
    public static void main(String [] args)
    {
        Person [] people1 = new Person[3];
        Person [] people2 = people1; //Shallow copy #1
        people2 = new Person[3];
        int i;

        i = 0;
        while (i < people1.length)
        {
            people1[i] = new Person(("Name" + i),(i+1)); 
            i++;
        }        

        //Shallow copy #2 (error is subtle)
        i = 0;
        while (i < people1.length)
        {   
            people2[i] = people1[i]  ;     
            i++;
        } 

        System.out.println("Display right after copy");
        System.out.println("People1 array");
        i = 0;
        while (i < people1.length)
        {   
            System.out.println(people1[i]);       
            i++;
        } 
        System.out.println();
        System.out.println("People2 array");
        i = 0;
        while (i < people1.length)
        {   
            System.out.println(people1[i]);       
            i++;
        } 
        System.out.println();

        //First set of edits
        people1[0].setAge(7);
        people2[2].setAge(13);
        System.out.println("Display after first set of edits");
        System.out.println("People1 array");
        i = 0;
        while (i < people1.length)
        {   
            System.out.println(people1[i]);       
            i++;
        } 
        System.out.println();
        System.out.println("People2 array");
        i = 0;
        while (i < people1.length)
        {   
            System.out.println(people1[i]);       
            i++;
        } 
        System.out.println();

        //Create new objects for second array
        i = 0;
        while (i < people2.length)
        {   
            people2[i] = new Person();  
            i++;
        } 
        //An actual deep copy of arrays
        i = 0;
        while (i < people1.length)
        {   
            people1[i].setAge(123);
            people2[i].setAge(people1[i].getAge());     
            i++;
        } 
        //Second set of edits
        people1[0].setAge(7);
        people2[2].setAge(13);
        System.out.println("Display after second set of edits");
        System.out.println("People1 array");
        i = 0;
        while (i < people1.length)
        {   
            System.out.println(people1[i]);       
            i++;
        } 
        System.out.println();
        System.out.println("People2 array");
        i = 0;
        while (i < people1.length)
        {   
            System.out.println(people2[i]);       
            i++;
        } 
        System.out.println();
    }
}