lab.util

Class Stack<E>

java.lang.Object

lab.util.Stack<E>

Type Parameters:

E - the element type to store in this stack

public class Stack<E>
extends Object

A stack data structure that supports O(1) push and pop operations at the top of the stack. This stack implementation also provides a method to look at the top element of the stack (peek) without popping the element.

Constructor Summary

Constructors

Constructor and Description
Stack() Creates an empty stack (size equal to zero).

Method Summary

Methods

Modifier and Type	Method and Description
boolean	equals(Object obj) Compares the specified object to this stack for equality.
Node<E>	getTop() Returns the node at the top of the stack.
int	hashCode() Returns a hash code for this stack.
boolean	isEmpty() Returns true if this stack is empty, and false otherwise.
E	peek() Returns the element that is on the top of this stack without popping it from the stack.
E	pop() Pop an element from the top of the stack returning the element.
void	push(E element) Push an element onto the top of the stack.
int	size() Get the size (number of elements) in the stack.
String	toString() Returns a string representation of this stack.

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

Stack

public Stack()

Creates an empty stack (size equal to zero).

Method Detail

isEmpty

public boolean isEmpty()

Returns true if this stack is empty, and false otherwise.

Returns:

true if this stack is empty, and false otherwise

size

public int size()

Get the size (number of elements) in the stack.

Returns:

the size (number of elements) in the stack

push

public void push(E element)

Push an element onto the top of the stack.

Parameters:

element - the element to push onto the stack

pop

public E pop()

Pop an element from the top of the stack returning the element. Throws a NoSuchElementException if the stack is empty.

Throws:

NoSuchElementException - if the stack is empty

Returns:

the element that was popped off of the top of this stack

peek

public E peek()

Returns the element that is on the top of this stack without popping it from the stack. Throws a NoSuchElementException if the stack is empty.

Throws:

NoSuchElementException - if the stack is empty

Returns:

the element that is on the top of this stack

equals

public boolean equals(Object obj)

Compares the specified object to this stack for equality. Two stacks are equal if they contain the same number of elements in the same order.

Overrides:

equals in class Object

See Also:

Object.equals(java.lang.Object)

Parameters:

obj - the object to compare to this stack for equality

Returns:

true if the specified object is equal to this stack

hashCode

public int hashCode()

Returns a hash code for this stack. The hash code is computed using the elements of this stack.

Overrides:

hashCode in class Object

See Also:

Object.hashCode()

Returns:

a hash code for this stack

toString

public String toString()

Returns a string representation of this stack. The string representation consists of a list of the stack's elements from the top of the stack to the bottom of the stack, enclosed in square brackets ("[]"). Adjacent elements are separated by the characters ", " (comma and space). Elements are converted to strings as by String.valueOf(Object).

Overrides:

toString in class Object

See Also:

Object.toString()

Returns:

a string representation of this stack

getTop

public Node<E> getTop()

Returns the node at the top of the stack. This method is here for debugging and testing purposes.

Returns:

the node at the top of the stack