Fast stack : Stack « Collections Data Structure « Java

Fast stack


//package com.thoughtworks.xstream.core.util;

public final class FastStack {

    private Object[] stack;
    private int pointer;

    public FastStack(int initialCapacity) {
        stack = new Object[initialCapacity];

    public Object push(Object value) {
        if (pointer + 1 >= stack.length) {
            resizeStack(stack.length * 2);
        stack[pointer++] = value;
        return value;

    public void popSilently() {
        stack[--pointer] = null;

    public Object pop() {
        final Object result = stack[--pointer]; 
        stack[pointer] = null; 
        return result;

    public Object peek() {
        return pointer == 0 ? null : stack[pointer - 1];

    public int size() {
        return pointer;

    public boolean hasStuff() {
        return pointer > 0;

    public Object get(int i) {
        return stack[i];

    private void resizeStack(int newCapacity) {
        Object[] newStack = new Object[newCapacity];
        System.arraycopy(stack, 0, newStack, 0, Math.min(pointer, newCapacity));
        stack = newStack;

    public String toString() {
        StringBuffer result = new StringBuffer("[");
        for (int i = 0; i < pointer; i++) {
            if (i > 0) {
                result.append(", ");
        return result.toString();


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