// Here are some classic java import statements, whenever you
// are trying to use a java object (ex. List or Scanner) you will
// need to first import that object
import java.util.*;
import java.io.*;

// To make a class you have two keywords
//       public : which means that the class is accesible to all other classes
//       class: this indicates a class
// followed by a name, this name will also have to be the name of the file
public class ArrayIntList {

   // Anytime you are making a data structure, you need to store data
   // this data is stored in global variables called fields in java
   // we want all our fields of a public class to be private
   private int[] arr;
   private int size;
   
   // to build a class you create constructors
   // java allows for multiple constructors, as long as each
   // constructor has different parameters
   public ArrayIntList() {
      // we use the keyword "this" to call another constructor
      // in the class, for instance here we are calling the second
      // constructor that takes in an int parameter
      this(100);
   }
   
   public ArrayIntList(int cap) {
      // fields are automatically initialized to the java null
      // (or null equivalent), in the constructor we initialize these
      // fields to something
      this.arr = new int[cap];
      // to reference a field, I can use the "this" keyword followed
      // by a period. However, this is not neccessary as long as there
      // are no other variables in local scope with the same name as your field
      this.size = 0;
   } 
   
   
   // Our method headers contain 4 parts
   //    1. "public" or "private" depending on whether or not the method should
   //       be allowed to be accessed from outside classes
   //    2. a return keyword, for instance in this method we used the keyword
   //       "void" to mean that no value is returned.
   //       If we wanted to return a different value, like an int we would
   //       replace the word "void" with the word "int"
   //    3. a name of the method, if you want a name to have more than one word,
   //       like addAtIndex, the name must be camelCased
   //    4. parameters, which will be a type of value followed by a name, separated by
   //       commas. In java there are not lambda parameters or optional parameters
   
   // This method adds a new value at an index
   public void add(int index, int value) {
      if (index < 0 || index > this.size) {
         // one way of error handeling is to throw exceptions
         // to throw an exception you use the two keywords 
         // "throw" "new" then the name of the exception followed by ()
         // do not write your own custom exceptions for this class
         throw new IllegalArgumentException();
      }
      size++;      
      int temp = this.arr[index];
      this.arr[index] = value;
      // there are several types of loops that will be useful for you in 
      // java, for loop (shown here), while loop, and for each loop
      // In a for loop we initialize a variable, give the stopping condition,
      // and then the update all seperated by semi-colons
      for (int i = index + 1; i < size; i++) {
         int temp2 = this.arr[i];
         this.arr[i] = temp;
         temp = temp2;
      }
   }
   
   // writing your own toString is a great way to help debug your classes
   // if you want to name your method "toString" you must take in no parameters
   // and return a string
   // this toString method doesn't work very well, because it prints a bunch of 0s
   // after our actual list, however it works well enough for the purposes of our
   // testing program
   public String toString() {
      return (Arrays.toString(this.arr));
   }

}