// This program is designed to introduce the concepts
// reference semantics and value semantics.

import java.util.*;

public class ArrayPractice {
   public static void main(String[] args) {
      // value semantics primitives int char boolean double
      int x = 5;
      int y = 7;
      System.out.println("x = " + x + ", y = " + y);
      swap(x, y);
      System.out.println("x = " + x + ", y = " + y);
      
      // Arrays, objects
      // Reference semantics
      String[] words = {"hip", "hip", "hooray"};
      String[] words2 = words; // words2 gets a reference to words
      words2[1] = "pimp"; // this changes words and words2
      
      // With reference semantics, changes that were made
      // in the modify method will change the words array
      // above.
      System.out.println("words = " + Arrays.toString(words));
      modify(words);
      System.out.println("words = " + Arrays.toString(words2));
   }
   
   // This method takes a reference 
   // to the array words that was made in main.
   // Since we have its reference, changes made to
   // the array in this method persist.
   public static void modify(String[] list) {
      list[0] = "pimp";
      list[2] = "array!";
   }
   
   
   // Since we dealing with primitives in this method.
   // We follow the rules of value semantics. Even though
   // we do swap the values of a and b within the method
   // this does not change x and y in main.
   public static void swap(int a, int b) {
      int temp = a;
      a = b;
      b = temp;
      System.out.println("a = " + a + ", b = " + b);
   }
   
}