Package org.apache.tapestry5.commons.util

## Class Stack<E>

- java.lang.Object
- - org.apache.tapestry5.commons.util.Stack<E>

- Type Parameters:
    `E` - the type of elements stored in the map

      public class Stack<E>
      extends Object

  A simple, streamlined implementation of `Stack`. The implementation is not threadsafe.
  See Also:
    `CollectionFactory.newStack()`

- - ### Constructor Summary

    Constructors
    Constructor | Description
    --- | ---
    `Stack()` | Normal constructor supporting an initial size of 20.
    `Stack​(int initialSize)` |

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method | Description
    --- | --- | ---
    `void` | `clear()` | Clears the stack, the same as popping off all elements.
    `int` | `getDepth()` | Returns the number of items currently in the stack.
    `Object[]` | `getSnapshot()` | Returns a snapshot of the current state of the stack as an array of objects.
    `boolean` | `isEmpty()` | Returns true if the stack is empty.
    `E` | `peek()` | Returns the top element of the stack without affecting the stack.
    `E` | `pop()` | Pops the top element off the stack and returns it.
    `void` | `push​(E item)` | Pushes a new item onto the stack.
    `String` | `toString()` | Describes the stack, listing the element in order of depth (top element first).

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

- - ### Constructor Detail

    - #### Stack

          public Stack()

      Normal constructor supporting an initial size of 20.

    - #### Stack

          public Stack​(int initialSize)

      Parameters:
        `initialSize` - the initial size of the internal array (which will be expanded as necessary). For best efficiency, set this to the maximum depth of the stack.

  - ### Method Detail

    - #### isEmpty

          public boolean isEmpty()

      Returns true if the stack is empty.

    - #### getDepth

          public int getDepth()

      Returns the number of items currently in the stack.

    - #### clear

          public void clear()

      Clears the stack, the same as popping off all elements.

    - #### push

          public void push​(E item)

      Pushes a new item onto the stack.

    - #### pop

          public E pop()

      Pops the top element off the stack and returns it.
      Returns:
        the top element of the stack
      Throws:
        `IllegalStateException` - if the stack is empty

    - #### peek

          public E peek()

      Returns the top element of the stack without affecting the stack.
      Returns:
        top element on the stack
      Throws:
        `IllegalStateException` - if the stack is empty

    - #### toString

          public String toString()

      Describes the stack, listing the element in order of depth (top element first).
      Overrides:
        `toString` in class `Object`
      Returns:
        string description of the stack

    - #### getSnapshot

          public Object[] getSnapshot()

      Returns a snapshot of the current state of the stack as an array of objects. The first object is the deepest in the stack, the last object is the most shallowest (most recently pushed onto the stack). The returned array may be manipulated (it is a copy).
      Returns:
        the stack as an object array