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asri71
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Adding Stack implementation along with test class
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‎src/main/java/com/dataStructures/Stack.java

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package src.main.java.com.dataStructures;
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import java.io.Serializable;
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import java.util.EmptyStackException;
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import java.util.Vector;
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public class Stack<E> extends Vector implements Serializable {
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/**
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* Inital capacity alloted to stack on object creation
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*/
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private final int INITIAL_CAPACITY = 10;
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/**
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* Increment in memory space once stack is out of space
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*/
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private final int EXNTEDED_CAPACITY = 10;
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/**
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* Position of tail in stack
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*/
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private int tail = -1;
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/**
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* Size of stack at any given time
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*/
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private int size;
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/**
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* Uninitialized array to hold stack elements.
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* WIll be intialized with inital capacity once the object is created
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*/
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private Object[] elements;
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/**
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* No argument to create stack object with inital capacity
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*/
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public Stack() {
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elements = new Object[INITIAL_CAPACITY];
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}
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/**
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* Method to check if the given stack is empty or not
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*/
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public boolean empty() {
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if(null == elements) {
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return true;
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}
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if(size == 0){
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return true;
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}
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return false;
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}
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/**
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* Method to check the element on head without removing it
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*/
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public Object peek() {
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if(empty()) {
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throw new EmptyStackException();
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}
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return elements[tail];
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}
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/**
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* Method to remove the top element from stack
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*/
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public Object pop() {
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if(empty()) {
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throw new EmptyStackException();
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}
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Object removedElement = elements[tail];
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tail--;
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size--;
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return removedElement;
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}
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/**
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* Method to add element to stack
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*/
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public Object push(Object e) {
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boolean isSuccess = false;
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if(tail < (INITIAL_CAPACITY - 1)){
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tail++;
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elements[tail] = e;
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}else{
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Object[] extendedElements = new Object[INITIAL_CAPACITY + EXNTEDED_CAPACITY];
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System.arraycopy(elements, 0, extendedElements, 0, (tail+1));
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elements = extendedElements;
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tail++;
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elements[tail] = e;
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}
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size++;
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return e;
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}
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/**
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* Method to search for an element in stack
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*/
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public int search(Object o) {
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int index = -1;
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boolean found = false;
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if(empty()) {
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return -1;
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}
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for(int i=0; i<size();i++) {
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if(elements[i] == o) {
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index = i;
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found = true;
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break;
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}
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}
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if(found) {
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index = tail - index + 1;
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}
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return index;
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}
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/**
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* Method to get size of stack
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*/
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public int size() {
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return size;
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}
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}

‎src/test/java/com/dataStructures/StackTest.java

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package src.test.java.com.dataStructures;
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import org.junit.Assert;
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import org.junit.Test;
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import src.main.java.com.dataStructures.Stack;
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import java.util.EmptyStackException;
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public class StackTest {
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@Test
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public void testEmpty() {
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Stack<Integer> myStack = new Stack<>();
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boolean isEmpty = myStack.empty();
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Assert.assertTrue(isEmpty);
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myStack.push(10);
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isEmpty = myStack.empty();
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Assert.assertFalse(isEmpty);
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}
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@Test(expected = EmptyStackException.class)
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public void testPeekWithoutElements() {
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Stack<Integer> myStack = new Stack<>();
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myStack.peek();
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}
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@Test
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public void testPeekWithElements() {
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Stack<Integer> myStack = new Stack<>();
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myStack.push(10);
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myStack.push(20);
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myStack.push(30);
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myStack.push(40);
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Assert.assertEquals(40, myStack.peek());
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}
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@Test(expected = EmptyStackException.class)
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public void testPopWithoutElements() {
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Stack<Integer> myStack = new Stack<>();
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myStack.pop();
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}
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@Test
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public void testPopWithElements() {
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Stack<Integer> myStack = new Stack<>();
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myStack.push(10);
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myStack.push(20);
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myStack.push(30);
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myStack.push(40);
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myStack.push(50);
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Assert.assertEquals(50, myStack.pop());
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}
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@Test
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public void testPushWithinInitialCapacity() {
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Stack<Integer> myStack = new Stack<>();
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myStack.push(10);
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myStack.push(20);
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myStack.push(30);
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myStack.push(40);
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myStack.push(50);
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myStack.push(60);
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myStack.push(70);
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myStack.push(80);
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myStack.push(90);
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myStack.push(100);
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Assert.assertEquals(10, myStack.size());
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}
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@Test
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public void testPushOutsideInitialCapacity() {
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Stack<Integer> myStack = new Stack<>();
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myStack.push(10);
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myStack.push(20);
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myStack.push(30);
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myStack.push(40);
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myStack.push(50);
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myStack.push(60);
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myStack.push(70);
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myStack.push(80);
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myStack.push(90);
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myStack.push(100);
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myStack.push(110);
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Assert.assertEquals(11, myStack.size());
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}
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@Test
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public void testSearchWithObjectUnavailable() {
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Stack<Integer> myStack = new Stack<>();
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myStack.push(10);
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myStack.push(20);
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myStack.push(30);
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Assert.assertEquals(-1,myStack.search(50));
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}
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@Test
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public void testSearchWithObjectAvailable() {
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Stack<Integer> myStack = new Stack<>();
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myStack.push(10);
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myStack.push(20);
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myStack.push(30);
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Assert.assertEquals(3,myStack.search(10));
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}
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}

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