Stacks

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Stack linked list implementation

	package com.tvidushi.stack.stack;
	import com.tvidushi.stack.exception.StackOverFlowException;
	import com.tvidushi.stack.exception.StackUnderFlowException;
	public class StackLlistImpl<T> implements IStack{
	Node head;
	public StackLlistImpl(Node node) {
	this.head = node;
	}
	public void push(Object num) throws StackOverFlowException {
	if(head == null){
	head = new Node(num,null);
	return;
	}
	Node previous = head;
	head = new Node(num,previous);
	}
	public T peek() throws StackUnderFlowException {
	if(head == null) throw new StackUnderFlowException("Stack is empty ");
	return (T) head.data;
	}
	public T pop() throws StackUnderFlowException {
	if(isEmpty()) throw new StackUnderFlowException("") ;
	T value = (T) head.data;
	head = head.next;
	return value;
	}
	public boolean isEmpty() {
	return false;
	}
	public boolean isFull() {
	return false;
	}
	public static class Node<T> {
	Node next;
	T data;
	public Node(T data, Node node){
	this.next = node;
	this.data = data;
	}
	}
	}

view raw StackLlistImpl.java hosted with ❤ by GitHub

Stack array implementation

	package com.tvidushi.stack.stack;
	import com.tvidushi.stack.exception.StackUnderFlowException;
	import com.tvidushi.stack.exception.StackOverFlowException;
	public class StackArrayImpl implements IStackArray {
	int top;
	Integer[] num ;
	int size;
	//STEP 1: initialize the array
	public StackArrayImpl(int top,int size,Integer[] num) {
	this.size =size;
	this.top = top;
	this.num = num;
	}
	public void push(Integer number) throws StackOverFlowException {
	if(isFull()){
	throw new StackOverFlowException("Stack over flow");
	}
	num[++top] = number;
	System.out.println(" Element pushed "+num[top]);
	}
	public Integer pop() throws StackUnderFlowException {
	if(isEmpty()) throw new StackUnderFlowException("");
	int currentElement = top;
	top--;
	System.out.println(" Element pop "+num[currentElement]);
	return num[currentElement];
	}
	public Integer peek() throws StackUnderFlowException {
	if(isEmpty()) throw new StackUnderFlowException("");
	return num[top];
	}
	public boolean isEmpty(){
	return (top==-1);
	}
	public boolean isFull(){
	return (top==size-1);
	}
	}

view raw StackArrayImpl.java hosted with ❤ by GitHub

 package com.tvidushi.stack;  
 import org.junit.Test;  
 import com.tvidushi.stack.exception.StackOverFlowException;  
 import com.tvidushi.stack.exception.StackUnderFlowException;  
 import com.tvidushi.stack.stack.StackLlistImpl;  
 import com.tvidushi.stack.stack.StackLlistImpl.Node;  
 import junit.framework.TestCase;  
 /**  
  * @author takshila.vidushi  
  *  
  */  
 public class TestStackLlistImpl extends TestCase {  
      StackLlistImpl stack = new StackLlistImpl(new Node(90,null));  
        public void setup() {  
        }       
        @Test  
        public void testPush() throws StackOverFlowException {       
                  stack.push(45);  
                  stack.push(89);;  
        }  
        @Test  
        public void testPeek() throws StackUnderFlowException {       
                  stack.peek();  
        }  
        @Test  
        public void testPop() throws StackUnderFlowException {       
                  stack.pop();  
        }  
        @Test(expected =StackUnderFlowException.class)  
        public void testPop1() throws StackUnderFlowException {       
                  stack.pop();  
        }  

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