import java.util.*;

public class ArrayExamples {
   public static void main(String[] args) {
      mystery();
      System.out.println();
      
      // We saw that we could pass arrays as parameters.
      int[] evens = {2, 4, 6, 8};
      sumEvens(evens);
      
      // value semantics vs. reference semantics
      // primitive       vs. arrays, other Objects
      
      // value semantics:
      int x = 7;
      int y = 14;
      int z = x;
      // note that z and x are not connected! z gets a copy of
      // whatever x was. So changes to one variable do not affect
      // the other.

      System.out.println("BEFORE x: " + x + " y: " + y + " z: " + z);
      swap(x, y);     
      System.out.println("AFTER x: " + x + " y: " + y + " z: " + z);
      System.out.println();
      
      // reference semantics:
      int[] list = {1, 2, 3};
      int[] list2 = list;
      // both list and list2 store a reference to the same 
      // array, so changing either list or list2 changes
      // the array.
      
      System.out.println("BEFORE list = " + Arrays.toString(list));
      modify(list);
      System.out.println("AFTER list = " + Arrays.toString(list));
      
   }
   
   public static void modify(int[] list) {
      list[0] = list[list.length - 1];
   }
   
   
   public static void swap(int a, int b) {
      // a = 7, b = 14
      int temp = a;
      a = b;   
      b = temp;   // a = 14; b = 7
   }
   
   public static void sumEvens(int[] evens) {
      int sum = 0;
      for (int i = 0; i < evens.length; i++) {
         sum += evens[i];
      }
      System.out.println("sum: " + sum);
      System.out.println();
   }


   public static void mystery() {
      int[] a = {1, 7, 5, 6, 4, 14, 11};
      
      // for (int i = 0; i < a.length; i++   // standard loop traversal
      for (int i = 0; i < a.length - 1; i ++) {
         if (a[i] > a[i + 1]) {
            a[i + 1] = a[i + 1] * 2;
         }
      }
      System.out.println("mystery array = " + Arrays.toString(a));
   }
}