org.daisy.dotify.common.collection.ArrayStack Maven / Gradle / Ivy
package org.daisy.dotify.common.collection;
import java.util.ArrayList;
import java.util.Collection;
import java.util.EmptyStackException;
/**
* Provides a simple unsynchronized stack based on ArrayList instead of Vector.
* This class implements the exact same methods as {@link java.util.Stack} and is
* therefore easily interchangeable with the former.
* However, {@link java.util.ArrayDeque} should for most purposes
* be used instead of this class.
*
* @param the type of elements in the stack
* @author Joel Håkansson
* @see java.util.Deque
*/
public class ArrayStack extends ArrayList {
/**
*
*/
private static final long serialVersionUID = 7549882261530382669L;
/**
* Constructs an empty stack with an initial capacity of ten.
*/
public ArrayStack() {
super();
}
/**
* Constructs a stack containing the elements of the specified
* collection, in the order they are returned by the collection's
* iterator.
*
* @param c the collection whose elements are to be placed into this stack
* @throws NullPointerException if the specified collection is null
*/
public ArrayStack(Collection c) {
super(c);
}
/**
* Constructs an empty stack with the specified initial capacity.
*
* @param initialCapacity the initial capacity of the stack
* @throws IllegalArgumentException if the specified initial capacity
* is negative
*/
public ArrayStack(int initialCapacity) {
super(initialCapacity);
}
/**
* Pushes an item onto the top of this stack. This has exactly
* the same effect as:
* add(item)
*
* @param item the item to be pushed onto this stack.
* @return the item argument.
* @see java.util.ArrayList#add
*/
public E push(E item) {
add(item);
return item;
}
/**
* Removes the object at the top of this stack and returns that
* object as the value of this function.
*
* @return The object at the top of this stack (the last item
* of the List object).
* @throws EmptyStackException if this stack is empty.
*/
public E pop() {
E obj;
int len = size();
if (len == 0) {
throw new EmptyStackException();
}
obj = get(len - 1);
remove(len - 1);
return obj;
}
/**
* Looks at the object at the top of this stack without removing it
* from the stack.
*
* @return the object at the top of this stack (the last item
* of the List object).
* @throws EmptyStackException if this stack is empty.
*/
public E peek() {
int len = size();
if (len == 0) {
throw new EmptyStackException();
}
return get(len - 1);
}
/**
* Tests if this stack is empty.
*
* @return true if and only if this stack contains
* no items; false otherwise.
*/
public boolean empty() {
return size() == 0;
}
/**
* 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.
*
* @param o the desired object.
* @return 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.
*/
public int search(Object o) {
int i = lastIndexOf(o);
if (i >= 0) {
return size() - i;
}
return -1;
}
}