DataStructure/StackAL.java at master · darshanpatel44/DataStructure · GitHub

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class StackAL<D> implements Stack<D>
{

Integer buffer=0;
Integer size=0;

Object arr[];

	StackAL(Integer b)
	{
		buffer=b;
		arr=new Object[buffer];
	}

		public void push(D o)
		{


			if(size==buffer)
			{
				buffer=buffer*2;

				Object arr2[]=new Object[buffer];

				for(Integer i=0;i<size;i++)
				{

					arr2[i]=arr[i];

				}

				arr=arr2;


			}

			arr[size]=o;
			size++;

		}


		public D pop()
		{

			try
			{

				if(size<=0)
				{

					BoundsException ob=new BoundsException();
					throw ob;

				}

			}


			catch(BoundsException ob)
			{

				ob.printError();
				return null;

			}

			Object temp=arr[size-1];

			arr[size-1]=null;
			size--;

			return (D)temp;
		}


		public D peek()
		{

			try
			{

				if(size<=0)
				{

					BoundsException ob=new BoundsException();
					throw ob;

				}

			}


			catch(BoundsException ob)
			{

				ob.printError();
				return null;

			}

			return (D) arr[size-1];

		}


}