java.util
Class Stack
java.lang.Object
|
+--java.util.AbstractCollection
|
+--java.util.AbstractList
|
+--java.util.Vector
|
+--java.util.Stack
- public class Stack
- extends Vector
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.
- Since:
- JDK1.0
- See Also:
- Serialized Form
Constructor Summary |
Stack()
Creates an empty Stack. |
Method Summary |
boolean |
empty()
Tests if this stack is empty. |
Object |
peek()
Looks at the object at the top of this stack without removing it
from the stack. |
Object |
pop()
Removes the object at the top of this stack and returns that
object as the value of this function. |
Object |
push(Object 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 inherited from class java.util.Vector |
add,
add,
addAll,
addAll,
addElement,
capacity,
clear,
clone,
contains,
containsAll,
copyInto,
elementAt,
elements,
ensureCapacity,
equals,
firstElement,
get,
hashCode,
indexOf,
indexOf,
insertElementAt,
isEmpty,
lastElement,
lastIndexOf,
lastIndexOf,
remove,
remove,
removeAll,
removeAllElements,
removeElement,
removeElementAt,
removeRange,
retainAll,
set,
setElementAt,
setSize,
size,
subList,
toArray,
toArray,
toString,
trimToSize |
Stack
public Stack()
- Creates an empty Stack.
push
public Object push(Object 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(java.lang.Object)
pop
public Object 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 Object 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.
Submit a bug or feature Version 1.2 of Java Platform API Specification
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