/*
* Copyright 2014 NAVER Corp.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.navercorp.pinpoint.web.util;
import java.util.LinkedList;
/**
* @author emeroad
*/
public class Stack<T> {
private final LinkedList<T> stack = new LinkedList<>();
public void push(T obj) {
if (obj == null) {
throw new NullPointerException("obj must not be null");
}
stack.add(obj);
}
public T getLast() {
return stack.getLast();
}
public T pop() {
return stack.pollLast();
}
public T getParent() {
final int parent = stack.size() - 2;
if (parent < 0) {
return null;
}
return stack.get(parent);
}
public int size() {
return stack.size();
}
public T get(int index) {
return stack.get(index);
}
@Override
public String toString() {
return "Stack{" +
"stack=" + stack +
'}';
}
}