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jbreport.util
Class Stack  

java.lang.Object
  jbreport.util.Stack

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public class Stack

extends java.lang.Object

This provides for the semantics of a stack. By default it uses a java.util.ArrayList for management, but this can be changed by passing the appropriate java.util.List instance to the alternate constructor.

This is otherwise known as a FILO (First in, last out) list.

The existing stack from the java.util.* package was not used, as it is extended from the Vector class, which is fully synchronized. This is not a behaviour that is needed by default. IMHO. We do provide for all of the methods in the java.util.Stack class tho'.

Version:

$Revision: 1.1.1.1 $

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Field Summary
private  java.util.List	backingList           The list instance that is used to store and manage the stack.

 

Constructor Summary

Stack()

Stack(java.util.List backingList)

 

Method Summary
void	clear()           Removes all of the elements from this stack (optional operation).
boolean	empty()           Tests if this stack is empty.
boolean	equals(java.lang.Object obj)           Determine whether this Object is semantically equal to another Object.
int	hashCode()           Get a value that represents this Object, as uniquely as possible within the confines of an int.
java.lang.Object	peek()           Looks at the object at the top of this stack without removing it from the stack.
java.lang.Object	peek(int index)           Looks at the object at the position relative to the top of the stack.
java.lang.Object	pop()           Removes the object at the top of this stack and returns that object as the value of this function.
java.lang.Object	push(java.lang.Object item)           Pushes an item onto the top of this stack.
int	search(java.lang.Object o)           Returns the 1-based position where an object is on this stack.

 

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

 

Field Detail

backingList

private java.util.List backingList

The list instance that is used to store and manage the stack.

Constructor Detail

Stack

public Stack()

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Stack

public Stack(java.util.List backingList)

Method Detail

clear

public void clear()

Removes all of the elements from this stack (optional operation). This stack will be empty after this call returns (unless it throws an exception).

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push

public java.lang.Object push(java.lang.Object item)

Pushes an item onto the top of this stack.

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pop

public java.lang.Object pop()

Removes the object at the top of this stack and returns that object as the value of this function.

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peek

public java.lang.Object peek()

Looks at the object at the top of this stack without removing it from the stack.

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peek

public java.lang.Object peek(int index)

Looks at the object at the position relative to the top of the stack.

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empty

public boolean empty()

Tests if this stack is empty.

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search

public int search(java.lang.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.

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hashCode

public int hashCode()

Description copied from class: java.lang.Object

Get a value that represents this Object, as uniquely as possible within the confines of an int.

There are some requirements on this method which subclasses must follow:

• Semantic equality implies identical hashcodes. In other words, if a.equals(b) is true, then a.hashCode() == b.hashCode() must be as well. However, the reverse is not necessarily true, and two objects may have the same hashcode without being equal.
• It must be consistent. Whichever value o.hashCode() returns on the first invocation must be the value returned on all later invocations as long as the object exists. Notice, however, that the result of hashCode may change between separate executions of a Virtual Machine, because it is not invoked on the same object.

Notice that since hashCode is used in java.util.Hashtable and other hashing classes, a poor implementation will degrade the performance of hashing (so don't blindly implement it as returning a constant!). Also, if calculating the hash is time-consuming, a class may consider caching the results.

The default implementation returns System.identityHashCode(this)

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equals

public boolean equals(java.lang.Object obj)

Description copied from class: java.lang.Object

Determine whether this Object is semantically equal to another Object.

There are some fairly strict requirements on this method which subclasses must follow:

• It must be transitive. If a.equals(b) and b.equals(c), then a.equals(c) must be true as well.
• It must be symmetric. a.equals(b) and b.equals(a) must have the same value.
• It must be reflexive. a.equals(a) must always be true.
• It must be consistent. Whichever value a.equals(b) returns on the first invocation must be the value returned on all later invocations.
• a.equals(null) must be false.
• It must be consistent with hashCode(). That is, a.equals(b) must imply a.hashCode() == b.hashCode(). The reverse is not true; two objects that are not equal may have the same hashcode, but that has the potential to harm hashing performance.

This is typically overridden to throw a java.lang.ClassCastException if the argument is not comparable to the class performing the comparison, but that is not a requirement. It is legal for a.equals(b) to be true even though a.getClass() != b.getClass(). Also, it is typical to never cause a java.lang.NullPointerException.

In general, the Collections API (java.util) use the equals method rather than the == operator to compare objects. However, java.util.IdentityHashMap is an exception to this rule, for its own good reasons.

The default implementation returns this == o.

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