// ExceptionsDemo1

import java.util.ArrayList;

public class ExceptionsDemo1
{
   public static void main(String[] args)
   {
      int numerator = 4;
      int denominator = 0;
      System.out.println(numerator/denominator); // ArithmeticException - you can't divide an int by zero
		
      int[] scores = {100, 82, 93, 75};
      scores[3] = 99; 		// no problem, the 75 is overwritten with the value 99 in index position 3
      scores[10] = 99; 		// ArrayIndexOutOfBoundsException - there is no index position 10
      scores[4] = 99; 		// ArrayIndexOutOfBoundsException - there is no index position 4 
	                        // even though the length of the array is 4
		
      ArrayList<Integer> numbers = new ArrayList<Integer>();  // an ArrayList of Integer objects
      numbers.add(new Integer(19610));    // adding an Integer object with the value 19610 (Wyomissing's zip code) 
                                          // to numbers, an ArrayList of Integer objects
      numbers.add(19611);                 // taking advantage of Java "autoboxing" the int value 19611 (West Reading's
                                          // zip code) as an Integer object
											
      // String wyoZipCode = ((String) numbers).get(0);    // ClassCastException - you can't cast an Integer to a String
      String westReadingZipCode = numbers.get(0) + "";  // you can concatenate an empty string to an autounboxed int value though
		
      System.out.println(westReadingZipCode); 	      
		
      ArrayList<String> words = new ArrayList<String>(); 
      words.add("Wyomissing"); 
      words.add("Reading");
      words.add("Kutztown");
      System.out.println(words.get(1));   // displays Reading which is in index position 1 of the ArrayList words
      System.out.println(words.get(13));  // IndexOutOfBoundsException - the ArrayList doesn't have an index position number 13
      System.out.println(words.get(3));   // IndexOutOfBoundsException - the ArrayList doesn't even have an index position number 3
                                          // even though the size of the ArrayList is 3
      // IndexOutOfBoundsException is practically the same as ArrayIndexOutOfBoundsException except it occurs with ArrayLists instead of arrays
		
      String name1 = "";                  // name1 is declared as an object variable and it has been instantiated as an actual object
      System.out.println(name1.length()); // the length of name1 is 0		
      String name2;		                  // name2 is declared as an object variable but it is not instantiated as an actual object
	  // System.out.println(name2.length()); // NullPointerException - name2 hasn't been instantiated yet so it doesn't really exist & has no length
      String name3 = null;                // name3 is declared as an object variable but it is not instantiated as an actual object
      System.out.println(name3.length()); // NullPointerException - name3 hasn't been instantiated yet so it doesn't really exist & has no length
	

      int[] nums1 = new int[5];           // nums1 is an array variable that is declared and instantiated with a length of 5
      nums1[2] = 5;                       // nums1 is now {0, 0, 5, 0, 0}	
      int[] nums2;                        // nums2 is declared as an array variable but it is not instantiated as an actual object
      // nums2[2] = 5;                       //  NullPointerException - nums2 hasn't been instantiated yet so it doesn't really exist
		
      String animal1 = "cat";
      System.out.println(animal1.substring(1, 2));    // displays "a" 
		                                          
      String animal2 = "dog";
      System.out.println(animal2.substring(2, 3));    // displays "g" since we start at the character in index position 2 and extract 
                                                      // everything up to but not including index position 3
													 
      String animal3 = "owl";
      System.out.println(animal3.substring(15, 16));  // StringIndexOutOfBoundsException - clearly an error since there is no index
                                                      // position 15 in "owl"
													   
      String animal4 = "cow";
      System.out.println(animal4.substring(3, 4));    // StringIndexOutOfBoundsException - there is no index position 3 in "cow"												
 
      System.out.println(computeSalesTax(-10)); 
      // IllegalArgumentException - the method "throws" an IllegalArgumentException 
      // since it's logically impossible to have a negative price. This is rarely covered on the AP exam.
 
      // IllegalStateException - example will may be demonstrated in class. This is rarely covered on the AP exam.
   }
 
   public static double computeSalesTax(double basePrice)
   {
      if (basePrice <= 0)
      {
         throw new IllegalArgumentException("The base price must be greater than zero.");
      }
 
      return basePrice * 0.06;
   }
 
}