comparison src/uk/ac/qmul/eecs/ccmi/utilities/Stack.java @ 0:e0ee6ac3a45f

first import

+/*  
+ CCmI Diagram Editor for Android 
+  
+ Copyright (C) 2012  Queen Mary University of London (http://ccmi.eecs.qmul.ac.uk/)
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+package uk.ac.qmul.eecs.ccmi.utilities;
+
+import java.util.ArrayList;
+
+/**
+ * 
+ * The stack is an {@code ArrayList} with a simplified interface for pushing and popping elements 
+ * on and from the top 
+ *
+ * @param <T> The type of objects contained in this stack
+ */
+public class Stack<T> extends ArrayList<T> {
+	
+	/**
+	 * Create a stack with an initial capacity of {@code size}
+	 *  
+	 * @param size the initial capacity 
+	 */
+	public Stack(int size){
+		super(size);
+	}
+	
+	/**
+	 * Returns the size of the stack 
+	 * 
+	 * @return the size of the stack
+	 */
+	@Override
+	public int size(){
+		return super.size();
+	}
+	
+	/**
+	 * Return the index of the top element for the stack 
+	 * 
+	 * @return index of the top element for the stack or -1 if the stack is empty
+	 */
+	public int level(){
+		return size()-1;
+	}
+	
+	/**
+	 * Adds a new element at the top of the stack. Like in an {@code ArrayList}, 
+	 * the same object can be inserted more than once in the stack
+	 * 
+	 * @param n the new element to add
+	 */
+	public void push(T n){
+		add(n);
+	}
+	
+	/**
+	 * Removes the top element of the stack
+	 * 
+	 * @return the removed element or {@code null} if the stack is empty 
+	 */ 
+	public T pop(){
+		if(size() == 0)
+			return null;
+		return remove(size()-1);
+	}
+	
+	/**
+	 * Returns a reference to the top element of the stack, the element is not removed 
+	 * 
+	 * @return the top element of the stack 
+	 */
+	public T current(){
+		if(size() == 0)
+			return null;
+		return get(size()-1);
+	}
+	
+	private static final long serialVersionUID = 1L;
+}