// Short program showcasing more practice problems with
// arrays.

import java.util.*;

public class ArrayPractice2 {
   public static void main(String[] args) {
      int[] arr = {-17, 5, -30, -12, 26, 10};  // quick initialization syntax
      int[] arr2 = {6, 12, 18};             // quick initialization syntax
      
      // reference semantics
      System.out.println("arr " + Arrays.toString(arr));
      applyAbs(arr);
      System.out.println("abs " + Arrays.toString(arr));
      System.out.println();
      
      System.out.println("arr " + Arrays.toString(arr));
      System.out.println("arr2 " + Arrays.toString(arr2));
      int[] concatenated = concatenate(arr, arr2);
      System.out.println("concatenated " + Arrays.toString(concatenated)); 
      arr[5] = 32;  
      System.out.println("concatenated " + Arrays.toString(concatenated)); 
      System.out.println("arr " + Arrays.toString(arr));


   }
   
   // Applies absolute value to all elements in the given array
   // ex: {-17, 5, -30, -12, 26, 10} --> {17, 5, 30, 12, 26, 10}
   // int[] list: the list to apply the absolute value on
   public static void applyAbs(int[] list) {
      for (int i = 0; i < list.length; i++) {
         // do something with list[i]
         list[i] = Math.abs(list[i]);
      }
      
   }
   
   // Returns a new array representing the result of concatenating the given arr1
   // and arr2 arrays (with values from arr1 to the left of the values from arr2)
   //       0, 1, 2,  3,  4,  5                     0,  1, 2,  3,  4,  5
   // ex: {17, 5, 30, 12, 26, 10}, {6, 12, 18} --> {17, 5, 30, 12, 26, 10, 6, 12, 18}
   // int[] list1: the first list whose values will be concatenated
   // int[] list2: the second list whose values will be concatenated
   public static int[] concatenate(int[] list1, int[] list2) {
      int[] result = new int[list1.length + list2.length];
            
      // copy contents from list1 result
      for (int i = 0; i < list1.length; i++) {
         result[i] = list1[i];
      }
      
      // copy contents from list2 result
      for (int i = 0; i < list2.length; i++) {
         result[i + list1.length] = list2[i];
      }
      
      // return result
      return result;
   }
   
}