Array List Version 1 - Java Pt. 1

/*
* Purpose: To create a class to manipulate an array of integers
*/

public class MyArrayList {

private int[] array; //stores an array of integers
private int capacity; //stores the length of the array
private int numElements; //stores the number of elements in the array

//default constructor
public MyArrayList(){

this(10);

}

//overloaded constructor
public MyArrayList(int capas){

this.array = new int[capas];
this.capacity = capas;
this.numElements = 0;

}

//copy constructor
public MyArrayList(MyArrayList list){

this(list.capacity);

//loops through the array
for(int i = 0; i < list.array.length; i++)
this.array[i] = list.array[i];

this.numElements = list.numElements;

}

//appends an integer to the end of the list
public void add(int element){

//determines if helper method needs to be called
if(this.numElements == this.capacity)
this.resize();

this.array[numElements] = element;
this.numElements++;

}

//places an element at the specified index
public void add(int index, int element) throws IndexOutOfBoundsException{

//determines of the specified index is valid
if(!(index < 0 || index > numElements)){

//determines if the helper method needs to be called
if(this.numElements == this.capacity)
this.resize();

//loops through the remainder of the array after specified index
for(int i = index; i this.array[i+1] = this.array[i];

this.array[index] = element;
this.numElements++;

}

else
throw new IndexOutOfBoundsException("Illegal index");
}

//returns the element at a given index
public int get(int index) throws IndexOutOfBoundsException{

//determines of the specified index is valid
if(!(index < 0 || index > numElements))
return(this.array[index]);

else
throw new IndexOutOfBoundsException("Illegal index");

}

//returns index of first location of element (-1 if not found)
public int indexOf(int element){

//loops through the array
for(int i = 0; i < this.array.length; i++)
//determines if the element in the index is the target
if(this.array[i] == element)
return(i);

return(-1);

}

//determines if the list has no elements in it
public boolean isEmpty(){

return(this.numElements == 0);

}

//removes and returns the element in the index specified
public int remove(int index) throws IndexOutOfBoundsException{

//determines of the specified index is valid
if(!(index < 0 || index > numElements)){

int temp = this.array[index];

//loops through the array
for(int i = index; i < this.numElements - 1; i++)
this.array[i] = this.array[i+1];

this.numElements--;
return(temp);

}

else
throw new IndexOutOfBoundsException("Illegal index");

}

//removes first instance of specified element from the array
public boolean removeElement(int element){

//loops through the array
for(int i = 0; i < this.array.length; i++)

//determines if the element in the index is the target
if(this.array[i] == element){

//loops through the array from index of element
for(int j = i; j < numElements - 1; j++)
this.array[j] = this.array[j+1];

this.numElements--;
return(true);

}

return(false);

}

//changes the element at a given position
public void set(int index, int element) throws IndexOutOfBoundsException{

//determines of the specified index is valid
if(!(index < 0 || index > numElements))
this.array[index] = element;

else
throw new IndexOutOfBoundsException("Illegal index");

}

//returns the total number of elements in the array
public int size(){

return(this.numElements);

}

//meaningful representation of an object of class MyArrayList
public String toString(){

String word = "-----";

//determines if the array is empty
if(!this.isEmpty()){

word = "{";

//loops through the array
for(int i = 0; i < this.numElements; i++){
word += this.array[i] + ", ";

}

word = word.substring(0, word.length() - 2);
word += "}";

}

return(word);

}

//helper method to resize the array if necessary
private void resize(){

int[] temp = new int[this.array.length * 2];

//loops through the array
for(int i = 0; i < this.array.length; i++)
temp[i] = this.array[i];

this.array = temp;
this.capacity *= 2;

}

//client program used to test the class
public static void main(String[] args){

MyArrayList list = new MyArrayList();
MyArrayList my = new MyArrayList(5);

System.out.println(list);
System.out.println(my);

list.add(3);
System.out.println(list);
list.add(0, 2);
System.out.println(list);

MyArrayList array = new MyArrayList(list);

System.out.println(array);
System.out.println(array.remove(1));
System.out.println(array);

System.out.println(list.removeElement(2));
System.out.println(list);

System.out.println(list.get(0));
System.out.println(list.indexOf(3));
System.out.println(list.indexOf(5));

System.out.println(my.isEmpty());
System.out.println(my.size());

//adds seven elements to the my object
for(int i = 0; i < 7; i++)
my.add(i);

System.out.println(my.isEmpty());
System.out.println(my.size());

System.out.println(my);
my.set(2, 8);
System.out.println(my);

//all exceptions have been tested and work correctly

}

}