Class Stack<E>
- java.lang.Object
-
- java.util.AbstractCollection<E>
-
- java.util.AbstractList<E>
-
- java.util.Vector<E>
-
- java.util.Stack<E>
- All Implemented Interfaces:
-
Serializable
,Cloneable
,Iterable<E>
,Collection<E>
,List<E>
,RandomAccess
public class Stack<E> extends Vector<E>
The Stack
class represents a last-in-first-out (LIFO) stack of objects. It extends class Vector
with five operations that allow a vector to be treated as a stack. The usual push
and pop
operations are provided, as well as a method to peek
at the top item on the stack, a method to test for whether the stack is empty
, and a method to search
the stack for an item and discover how far it is from the top.
When a stack is first created, it contains no items.
A more complete and consistent set of LIFO stack operations is provided by the Deque
interface and its implementations, which should be used in preference to this class. For example:
Deque<Integer> stack = new ArrayDeque<Integer>();
- Since:
- 1.0
- See Also:
- Serialized Form
Field Summary
Fields declared in class java.util.Vector
capacityIncrement, elementCount, elementData
Fields declared in class java.util.AbstractList
modCount
Constructor Summary
Constructor | Description |
---|---|
Stack() | Creates an empty Stack. |
Method Summary
Modifier and Type | Method | Description |
---|---|---|
boolean | empty() | Tests if this stack is empty. |
E | peek() | Looks at the object at the top of this stack without removing it from the stack. |
E | pop() | Removes the object at the top of this stack and returns that object as the value of this function. |
E | push(E item) | Pushes an item onto the top of this stack. |
int | search(Object o) | Returns the 1-based position where an object is on this stack. |
Methods declared in class java.util.Vector
add, add, addAll, addAll, addElement, capacity, clear, clone, contains, containsAll, copyInto, elementAt, elements, ensureCapacity, equals, firstElement, forEach, get, hashCode, indexOf, indexOf, insertElementAt, isEmpty, iterator, lastElement, lastIndexOf, lastIndexOf, listIterator, listIterator, remove, remove, removeAll, removeAllElements, removeElement, removeElementAt, removeIf, removeRange, replaceAll, retainAll, set, setElementAt, setSize, size, spliterator, subList, toArray, toArray, toString, trimToSize
Methods declared in class java.lang.Object
finalize, getClass, notify, notifyAll, wait, wait, wait
Methods declared in interface java.util.Collection
parallelStream, stream, toArray
Methods declared in interface java.util.List
sort
Constructor Detail
Stack
public Stack()
Creates an empty Stack.
Method Detail
push
public E push(E item)
Pushes an item onto the top of this stack. This has exactly the same effect as:
addElement(item)
- Parameters:
-
item
- the item to be pushed onto this stack. - Returns:
- the
item
argument. - See Also:
Vector.addElement(E)
pop
public E pop()
Removes the object at the top of this stack and returns that object as the value of this function.
- Returns:
- The object at the top of this stack (the last item of the
Vector
object). - Throws:
-
EmptyStackException
- if this stack is empty.
peek
public E peek()
Looks at the object at the top of this stack without removing it from the stack.
- Returns:
- the object at the top of this stack (the last item of the
Vector
object). - Throws:
-
EmptyStackException
- if this stack is empty.
empty
public boolean empty()
Tests if this stack is empty.
- Returns:
-
true
if and only if this stack contains no items;false
otherwise.
search
public int search(Object o)
Returns the 1-based position where an object is on this stack. If the object o
occurs as an item in this stack, this method returns the distance from the top of the stack of the occurrence nearest the top of the stack; the topmost item on the stack is considered to be at distance 1
. The equals
method is used to compare o
to the items in this stack.
- Parameters:
-
o
- the desired object. - Returns:
- the 1-based position from the top of the stack where the object is located; the return value
-1
indicates that the object is not on the stack.