Stack

java.lang.Object
- Stack<Item>

All Implemented Interfaces:

java.lang.Iterable<Item>
```
public class Stack<Item>
extends java.lang.Object
implements java.lang.Iterable<Item>
```
This class is an implementation of a stack of generic items. The operations on the stack follow the LIFO (last-in first out) policy. The class implements the usual push (put on top of the stack) and pop (take from the top of the stack) operations, along with methods for peeking at the top element (without popping it), testing if the stack is empty, and iterating through the items in LIFO order.
This implementation uses a singly-linked list with a static nested class for linked-list nodes. For the version from the textbook, that uses a non-static nested class, see LinkedStack.
The push, pop, peek, size, and isEmpty operations all take constant time in the worst case.
For additional documentation, see Section 1.3, page 121, of "Algorithms", 4th Edition, by Robert Sedgewick and Kevin Wayne.

Constructor Summary

Constructors
Constructor and Description

Stack()
Initializes an empty stack.

Constructors
Constructor and Description
`Stack()` Initializes an empty stack.

Method Summary

Methods
Modifier and Type	Method and Description
`boolean`	`isEmpty()` Is this stack empty? Returns true if this stack is empty; false otherwise.
`java.util.Iterator<Item>`	`iterator()` Returns an iterator to this stack that iterates through the items in LIFO order.
`static void`	`main(java.lang.String[] args)` Unit test of this Stack class.
`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 item to this stack.
`int`	`size()` Returns the number of items in the stack.
`java.lang.String`	`toString()` Returns a string representation of this stack.

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

- Constructor Detail
  - Stack
```
public Stack()
```
    Initializes an empty stack.
- Method Detail
  - isEmpty
```
public boolean isEmpty()
```
    Is this stack empty? Returns true if this stack is empty; false otherwise.
  - size
```
public int size()
```
    Returns the number of items in the stack.
  - push
```
public void push(Item item)
```
    Adds item to this stack.
  - pop
```
public Item pop()
```
    Removes and returns the item most recently added to this stack. Throws java.util.NoSuchElementException if this stack is empty.
  - peek
```
public Item peek()
```
    Returns (but does not remove) the item most recently added to this stack. Throws java.util.NoSuchElementException if the stack is empty.
  - toString
```
public java.lang.String toString()
```
    Returns a string representation of this stack. Overrides toString method in java.lang.Object. The items on the stack appear in LIFO order, separated by spaces.
    
    Overrides:
    
    toString in class java.lang.Object
  - iterator
```
public java.util.Iterator<Item> iterator()
```
    Returns an iterator to this stack that iterates through the items in LIFO order.
    
    Specified by:
    
    iterator in interface java.lang.Iterable<Item>
  - main
```
public static void main(java.lang.String[] args)
```
    Unit test of this Stack class. Builds a stack of strings from the strings given on standard input; each item entered is pushed onto the stack, unless item is "-", in which case an item is popped from the stack. After input stream ends (this is signaled by typing Ctrl-z if you are using Windows or Ctrl-d if you are using Unix), prints the number of items left on the stack

Class Stack<Item>

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

Stack

Method Detail

isEmpty

size

push

pop

peek

toString

iterator

main