Building Stack T
Buidling Stack
public class LinkedList<T> {
private T data;
private LinkedList<T> prevNode, nextNode;
/**
* Constructs a new element
*
* @param data, data of object
* @param node, previous node
*/
public LinkedList(T data, LinkedList<T> node)
{
this.setData(data);
this.setPrevNode(node);
this.setNextNode(null);
}
/**
* Clone an object,
*
* @param node object to clone
*/
public LinkedList(LinkedList<T> node)
{
this.setData(node.data);
this.setPrevNode(node.prevNode);
this.setNextNode(node.nextNode);
}
/**
* Setter for T data in DoubleLinkedNode object
*
* @param data, update data of object
*/
public void setData(T data)
{
this.data = data;
}
/**
* Returns T data for this element
*
* @return data associated with object
*/
public T getData()
{
return this.data;
}
/**
* Setter for prevNode in DoubleLinkedNode object
*
* @param node, prevNode to current Object
*/
public void setPrevNode(LinkedList<T> node)
{
this.prevNode = node;
}
/**
* Setter for nextNode in DoubleLinkedNode object
*
* @param node, nextNode to current Object
*/
public void setNextNode(LinkedList<T> node)
{
this.nextNode = node;
}
/**
* Returns reference to previous object in list
*
* @return the previous object in the list
*/
public LinkedList<T> getPrevious()
{
return this.prevNode;
}
/**
* Returns reference to next object in list
*
* @return the next object in the list
*/
public LinkedList<T> getNext()
{
return this.nextNode;
}
}
public class Stack<T> {
private LinkedList<T> upper;
private int size;
// constructor initiates null LinkedList<T> object + set size to 0
public Stack() {
this.upper = null;
this.size = 0;
}
// push method for a new element to the upper value
public void push(T data) {
LinkedList<T> newNode = new LinkedList<T>(data, this.upper);
this.upper = newNode;
this.size++;
}
// peek method, return upper
public T peek() {
// try/catch to either return upper or print message if upper doesn't exist
try {
return this.upper.getData();
} catch (NullPointerException e) {
System.out.println("No upper element, empty stack!");
return null;
}
}
// pop method, return upper and remove
public T pop() {
// try/catch to either return + pop upper or print message if upper doesn't exist
try {
T data = this.upper.getData();
this.upper = this.upper.getPrevious();
this.size--;
return data;
} catch (NullPointerException e) {
System.out.println("No upper element, empty stack!");
return null;
}
}
// get size method
public int size() {
return this.size;
}
// isEmpty method, compare size to 0
public boolean isEmpty() {
return this.size == 0;
}
// toString method, from top to bottom
public String toString() {
String s = "[ ";
LinkedList<T> currentNode = upper;
// gets upper node, then keeps going down to previous until previous is null
while (currentNode != null) {
s += currentNode.getData();
currentNode = currentNode.getPrevious();
if (currentNode != null) {
s += ", ";
}
}
s += " ]";
return s;
}
}
public class Tester {
public static void main(String[] args) {
// test stack with Integer wrapper class
Stack<Integer> s1 = new Stack<Integer>();
s1.push(1);
s1.push(2);
s1.push(3);
s1.push(4);
s1.push(5);
System.out.println(s1.toString());
System.out.println(s1.peek());
System.out.println(s1.pop());
System.out.println(s1.peek());
System.out.println(s1.size());
System.out.println(s1.isEmpty());
// test stack with String class
Stack<String> s2 = new Stack<String>();
s2.push("Hello");
s2.push("my");
s2.push("name");
s2.push("is");
s2.push("Daniel");
System.out.println(s2.toString());
System.out.println(s2.peek());
System.out.println(s2.pop());
System.out.println(s2.peek());
System.out.println(s2.size());
System.out.println(s2.isEmpty());
}
}
Tester.main(null);
public class StackMerger<T> {
private final Stack<T> s1;
private final Stack<T> s2;
private Stack<T> s3;
// constructor for Stackmerger
public StackMerger(Stack<T> s1, Stack<T> s2) {
this.s1 = s1;
this.s2 = s2;
this.merge(s1, s2);
}
public void merge(Stack<T> s1, Stack<T> s2) {
Stack<T> mergedStack = new Stack<T>();
// if both stacks are not empty,
while (!s1.isEmpty() && !s2.isEmpty()) {
mergedStack.push(s1.pop());
mergedStack.push(s2.pop());
}
// if s1 is empty, pop from s2 and push to mergedStack
while (!s2.isEmpty()) {
mergedStack.push(s2.pop());
}
// if s2 is empty, pop from s1 and push to mergedStack
while (!s1.isEmpty()) {
mergedStack.push(s1.pop());
}
s3 = mergedStack;
}
// toString method using Stack<T> toString
public String toString() {
return s3.toString();
}
}
public class TesterTwo {
public static void main(String[] args) {
// test stack with Integer wrapper class
Stack<Integer> s1 = new Stack<Integer>();
s1.push(1);
s1.push(2);
s1.push(3);
s1.push(4);
s1.push(5);
System.out.println(s1.toString());
Stack<Integer> s2 = new Stack<Integer>();
s2.push(6);
s2.push(7);
s2.push(8);
s2.push(9);
s2.push(10);
System.out.println(s2.toString());
StackMerger<Integer> sm1 = new StackMerger<Integer>(s1, s2);
System.out.println(sm1.toString());
// test stack with String class
Stack<String> s3 = new Stack<String>();
s3.push("Hello");
s3.push("name");
s3.push("Daniel");
System.out.println(s3.toString());
Stack<String> s4 = new Stack<String>();
s4.push("my");
s4.push("is");
System.out.println(s4.toString());
StackMerger<String> sm2 = new StackMerger<String>(s3, s4);
System.out.println(sm2.toString());
}
}
TesterTwo.main(null);