Object
- Stack<Item>

Type Parameters:

Item - the generic type of each item in this stack

All Implemented Interfaces:

Iterable<Item>
```
public class Stack<Item>
extends Object
implements Iterable<Item>
```
The Stack class represents a last-in-first-out (LIFO) stack of generic items. It supports the usual push and pop operations, along with methods for peeking at the top item, testing if the stack is empty, getting the number of items in the stack, and iterating over the items in LIFO order.
This implementation uses a singly-linked list with a nested class for linked-list nodes. The push, pop, peek, size, and is-empty operations all take constant time in the worst case.
For additional documentation, see Section 4.3 of Computer Science: An Interdisciplinary Approach by Robert Sedgewick and Kevin Wayne.

Author:

Robert Sedgewick, Kevin Wayne

Constructor Summary

Constructors
Constructor Description

Stack()
Initializes an empty stack.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`boolean`	`isEmpty()`	Returns true if this stack is empty.
`Iterator<Item>`	`iterator()`	Returns an iterator to this stack that iterates through the items in LIFO order.
`static void`	`main(String[] args)`	Unit tests the `Stack` data type.
`Item`	`peek()`	Returns (but does not remove) the item most recently added to this stack.
`Item`	`pop()`	Removes and returns the item most recently added to this stack.
`void`	`push(Item item)`	Adds the item to this stack.
`int`	`size()`	Returns the number of items in this stack.
`String`	`toString()`	Returns a string representation of this stack.

Methods inherited from class java.lang.Object
clone, equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.lang.Iterable
forEach, spliterator

- Constructor Detail
  - Stack
```
public Stack()
```
    Initializes an empty stack.
- Method Detail
  - isEmpty
```
public boolean isEmpty()
```
    Returns true if this stack is empty.
    
    Returns:
    
    true if this stack is empty; false otherwise
  - size
```
public int size()
```
    Returns the number of items in this stack.
    
    Returns:
    
    the number of items in this stack
  - push
```
public void push(Item item)
```
    Adds the item to this stack.
    
    Parameters:
    
    item - the item to add
  - pop
```
public Item pop()
```
    Removes and returns the item most recently added to this stack.
    
    Returns:
    
    the item most recently added
    
    Throws:
    
    NoSuchElementException - if this stack is empty
  - peek
```
public Item peek()
```
    Returns (but does not remove) the item most recently added to this stack.
    
    Returns:
    
    the item most recently added to this stack
    
    Throws:
    
    NoSuchElementException - if this stack is empty
  - toString
```
public String toString()
```
    Returns a string representation of this stack.
    
    Overrides:
    
    toString in class Object
    
    Returns:
    
    the sequence of items in this stack in LIFO order, separated by spaces
  - iterator
```
public Iterator<Item> iterator()
```
    Returns an iterator to this stack that iterates through the items in LIFO order.
    
    Specified by:
    
    iterator in interface Iterable<Item>
    
    Returns:
    
    an iterator to this stack that iterates through the items in LIFO order
  - main
```
public static void main(String[] args)
```
    Unit tests the Stack data type.
    
    Parameters:
    
    args - the command-line arguments

Class Stack<Item>

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface java.lang.Iterable

Constructor Detail

Stack

Method Detail

isEmpty

size

push

pop

peek

toString

iterator

main