hw3: added idea

hw3/.gitignore

@@ -0,0 +1,2 @@
+artist.txt
+.idea/

hw3/report.tex

@@ -0,0 +1,135 @@
+\documentclass[a4paper]{article}
+
+\usepackage{graphicx}
+\usepackage[hidelinks]{hyperref}
+\usepackage[english]{babel}
+\usepackage{fancyhdr}
+\usepackage{listings}
+\usepackage{xcolor}
+\usepackage{float}
+\usepackage{lmodern}
+\usepackage[margin=2cm,top=2.5cm]{geometry}
+\hypersetup{pdfborder={0 0 0}}
+\usepackage[nomessages]{fp}
+
+\lstset{
+  basicstyle=\small\ttfamily,
+  %frame=shadowbox,
+  rulesepcolor=\color{black},
+  columns=fullflexible,
+  commentstyle=\color{gray},
+  keywordstyle=\color{blue},
+  mathescape=true,
+  aboveskip=1em,
+  captionpos=b,
+  abovecaptionskip=1em,
+  belowcaptionskip=1em
+}
+
+\fancyhead[R]{Advanced Java Programming -- Assignment 2 -- Federico Lagrasta,
+Claudio Maggioni}
+\pagestyle{fancy}
+
+
+\begin{document}
+
+\begin{titlepage}
+\scshape
+
+\centering
+\includegraphics[width=3cm, keepaspectratio]{logo_usi.png}
+\par 
+\vspace{0.1cm}
+\texttt{FACULTY OF INFORMATICS}
+\vspace{1cm}
+
+
+\raisebox{-\baselineskip}{\rule{\textwidth}{1px}}
+\rule{\textwidth}{1px}
+\vspace{0.2cm}
+
+    {\LARGE{{ADVANCED JAVA PROGRAMMING}}}\par \vspace{0.1cm}
+Assignment 3
+
+
+\rule{\textwidth}{2px}
+
+\vspace{1cm}
+
+
+\begin{tabular}{lp{1cm}l}
+  Author &  \rule{0pt}{3ex} & FEDERICO \mbox{LAGRASTA}\\
+  &&\\
+  & \rule{0pt}{3ex} & CLAUDIO \mbox{MAGGIONI}\\
+\end{tabular}
+
+\vspace{1.3cm}
+
+
+\vfill
+\today
+
+\end{titlepage}
+
+
+\section*{A}
+
+\subsection*{1}
+
+The code will trigger a compile time error at line 14, since the variable
+\textit{z} cannot be used inside a lambda as it is not final or effectively
+final. This is because line 14 attempts to mutate the variable, thus making the
+variable not effectively final.
+
+\subsection*{2}
+
+The code will not compile.
+
+\section*{B}
+
+\subsection*{1}
+
+According to the contract satisfied by the \texttt{java.util.HashSet} class,
+there is no guarantee on the iteration order of the elements. Therefore,
+\texttt{set.stream()} evaluates to a stream whose ordering contractually does
+not reflect the order of the list. However, by analyzing the Java 17 standard
+library sources, given that:
+
+\begin{itemize}
+    \item The elements of the source list are \textit{Integer}s and are already in natural order;
+    \item \textit{HashSet} uses a \textit{HashMap} by encapsulation to store its elements;
+    \item The \textit{Spliterator} returned by \textit{HashSet} is the \textit{Spliterator} over the keys
+    of the backing \textit{HashHap};
+    \item \textit{HashMap}'s spliterator implementation iterates over the key objects in the natural order
+    of each object's hash code;
+    \item \textit{Integer}'s \texttt{int hashCode()} implementation just returns the boxed \textit{int};
+\end{itemize}
+
+we can say that on any JVM this code is ran where the implementation of the
+standard library matches the sources provided with OpenJDK 17, we can say that
+in practice the \textit{Spliterator} backing the stream returned by
+\texttt{set.stream()} returns the elements in the correct order.
+
+However, the \texttt{java.util.stream} package
+documentation\footnote{\url{https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/util/stream/package-summary.html\#Ordering}},
+under the \textit{Ordering} section, explicitly mentions that the
+\textit{Stream} returned by an \textit{HashSet} is unordered. Therefore, also by
+the Stream API contract, we can say that the collection of this stream may
+result into a list that contractually is not in the order the elements were when
+creating the stream. However, in practice, since the created stream is
+sequential, the elements are kept in the given order as there is no performance
+advantage (unlike with parallel streams) in unordering them. Therefore,
+according to this contract, the method may throw a \textit{RuntimeException}
+even if this never happens in practice with any JVM with a standard library
+implementation matching the sources provided with OpenJDK 17.
+    \marginpar[right text]{\color{white}\url{https://youtu.be/oqO-nlrZNbc}}
+
+\subsection*{2}
+
+What said in the previous section still applies, however in this case line 31
+makes the stream parallel, and since the stream is contractually unordered there
+is no guarantee the elements may be collected in order since the stream API
+implementation may not follow the original ordering for parallelization
+performance reasons.
+
+\end{document}