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package com.modulus.common.collections;
import java.io.Serializable;
/**
* Class which uses an array to be used to
* implement a stack.
*
* This class is most efficient for
* nearly every purpose.
*
* @author jrahm
*
* @param <T> the type this stack holds
*/
public class ArrayStack<T> implements Stack<T>, Serializable{
private Object[] arr;
private int pointer = -1;
/**
* Creates a new ArrayStack with a
* default starting size of 10
*/
public ArrayStack(){
this(10);
}
/**
* Creates a new ArrayStack with
* a default starting size of <code>size</code>
* @param size
*/
public ArrayStack( int size ){
arr = new Object[size];
}
/**
* Ensures that this ArrayStack has enough space
* to store <code>size</code> number of elements.
*
* @param size the number of elements needed to store
*/
public void ensureSize( int size ){
if(arr.length > size)
return;
Object[] tmp = new Object[size*2];
for ( int i = 0;i < arr.length; i ++ ){
tmp[i] = arr[i];
}
arr = tmp;
}
@Override
public boolean isEmpty() {
return pointer == -1;
}
@SuppressWarnings("unchecked")
@Override
public T peek() {
return (T)arr[pointer];
}
@SuppressWarnings("unchecked")
@Override
public T pop() {
return (T) arr[ pointer -- ];
}
@Override
public void push(T obj) {
pointer ++;
this.ensureSize(pointer);
arr[pointer] = obj;
}
@Override
public int size() {
return pointer + 1;
}
@Override
public void clear(){
pointer = 0;
}
@Override
public String toString(){
StringBuffer buf = new StringBuffer("[");
for( int i = pointer; i >= 1; i --)
buf.append(arr[i] + ", ");
buf.append(arr[0] + "]");
return buf.toString();
}
}
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