\documentclass[10pt,a4paper]{article}

% Packages
\usepackage{fancyhdr}           % For header and footer
\usepackage{multicol}           % Allows multicols in tables
\usepackage{tabularx}           % Intelligent column widths
\usepackage{tabulary}           % Used in header and footer
\usepackage{hhline}             % Border under tables
\usepackage{graphicx}           % For images
\usepackage{xcolor}             % For hex colours
%\usepackage[utf8x]{inputenc}    % For unicode character support
\usepackage[T1]{fontenc}        % Without this we get weird character replacements
\usepackage{colortbl}           % For coloured tables
\usepackage{setspace}           % For line height
\usepackage{lastpage}           % Needed for total page number
\usepackage{seqsplit}           % Splits long words.
%\usepackage{opensans}          % Can't make this work so far. Shame. Would be lovely.
\usepackage[normalem]{ulem}     % For underlining links
% Most of the following are not required for the majority
% of cheat sheets but are needed for some symbol support.
\usepackage{amsmath}            % Symbols
\usepackage{MnSymbol}           % Symbols
\usepackage{wasysym}            % Symbols
%\usepackage[english,german,french,spanish,italian]{babel}              % Languages

% Document Info
\author{mjorod}
\pdfinfo{
  /Title (oca-java-se-programmer-i-java-basics.pdf)
  /Creator (Cheatography)
  /Author (mjorod)
  /Subject (OCA Java SE Programmer I . Java basics Cheat Sheet)
}

% Lengths and widths
\addtolength{\textwidth}{6cm}
\addtolength{\textheight}{-1cm}
\addtolength{\hoffset}{-3cm}
\addtolength{\voffset}{-2cm}
\setlength{\tabcolsep}{0.2cm} % Space between columns
\setlength{\headsep}{-12pt} % Reduce space between header and content
\setlength{\headheight}{85pt} % If less, LaTeX automatically increases it
\renewcommand{\footrulewidth}{0pt} % Remove footer line
\renewcommand{\headrulewidth}{0pt} % Remove header line
\renewcommand{\seqinsert}{\ifmmode\allowbreak\else\-\fi} % Hyphens in seqsplit
% This two commands together give roughly
% the right line height in the tables
\renewcommand{\arraystretch}{1.3}
\onehalfspacing

% Commands
\newcommand{\SetRowColor}[1]{\noalign{\gdef\RowColorName{#1}}\rowcolor{\RowColorName}} % Shortcut for row colour
\newcommand{\mymulticolumn}[3]{\multicolumn{#1}{>{\columncolor{\RowColorName}}#2}{#3}} % For coloured multi-cols
\newcolumntype{x}[1]{>{\raggedright}p{#1}} % New column types for ragged-right paragraph columns
\newcommand{\tn}{\tabularnewline} % Required as custom column type in use

% Font and Colours
\definecolor{HeadBackground}{HTML}{333333}
\definecolor{FootBackground}{HTML}{666666}
\definecolor{TextColor}{HTML}{333333}
\definecolor{DarkBackground}{HTML}{1D41A3}
\definecolor{LightBackground}{HTML}{F0F3F9}
\renewcommand{\familydefault}{\sfdefault}
\color{TextColor}

% Header and Footer
\pagestyle{fancy}
\fancyhead{} % Set header to blank
\fancyfoot{} % Set footer to blank
\fancyhead[L]{
\noindent
\begin{multicols}{3}
\begin{tabulary}{5.8cm}{C}
    \SetRowColor{DarkBackground}
    \vspace{-7pt}
    {\parbox{\dimexpr\textwidth-2\fboxsep\relax}{\noindent
        \hspace*{-6pt}\includegraphics[width=5.8cm]{/web/www.cheatography.com/public/images/cheatography_logo.pdf}}
    }
\end{tabulary}
\columnbreak
\begin{tabulary}{11cm}{L}
    \vspace{-2pt}\large{\bf{\textcolor{DarkBackground}{\textrm{OCA Java SE Programmer I . Java basics Cheat Sheet}}}} \\
    \normalsize{by \textcolor{DarkBackground}{mjorod} via \textcolor{DarkBackground}{\uline{cheatography.com/17938/cs/14018/}}}
\end{tabulary}
\end{multicols}}

\fancyfoot[L]{ \footnotesize
\noindent
\begin{multicols}{3}
\begin{tabulary}{5.8cm}{LL}
  \SetRowColor{FootBackground}
  \mymulticolumn{2}{p{5.377cm}}{\bf\textcolor{white}{Cheatographer}}  \\
  \vspace{-2pt}mjorod \\
  \uline{cheatography.com/mjorod} \\
  \end{tabulary}
\vfill
\columnbreak
\begin{tabulary}{5.8cm}{L}
  \SetRowColor{FootBackground}
  \mymulticolumn{1}{p{5.377cm}}{\bf\textcolor{white}{Cheat Sheet}}  \\
   \vspace{-2pt}Not Yet Published.\\
   Updated 18th December, 2017.\\
   Page {\thepage} of \pageref{LastPage}.
\end{tabulary}
\vfill
\columnbreak
\begin{tabulary}{5.8cm}{L}
  \SetRowColor{FootBackground}
  \mymulticolumn{1}{p{5.377cm}}{\bf\textcolor{white}{Sponsor}}  \\
  \SetRowColor{white}
  \vspace{-5pt}
  %\includegraphics[width=48px,height=48px]{dave.jpeg}
  Measure your website readability!\\
  www.readability-score.com
\end{tabulary}
\end{multicols}}




\begin{document}
\raggedright
\raggedcolumns

% Set font size to small. Switch to any value
% from this page to resize cheat sheet text:
% www.emerson.emory.edu/services/latex/latex_169.html
\footnotesize % Small font.

\begin{multicols*}{3}

\begin{tabularx}{5.377cm}{p{0.4977 cm} p{0.4977 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{Objectives}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{The structures and components of a Java class} \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
\mymulticolumn{2}{x{5.377cm}}{Understanding executable Java applications} \tn 
% Row Count 2 (+ 1)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{Understanding Java packages} \tn 
% Row Count 3 (+ 1)
% Row 3
\SetRowColor{white}
\mymulticolumn{2}{x{5.377cm}}{Importing Java packages into your code} \tn 
% Row Count 4 (+ 1)
% Row 4
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{Applying access and non access modifiers} \tn 
% Row Count 5 (+ 1)
% Row 5
\SetRowColor{white}
\mymulticolumn{2}{x{5.377cm}}{Features and components of Java} \tn 
% Row Count 6 (+ 1)
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{3.38436 cm} x{1.59264 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{Structure of a Java class}}  \tn
% Row 0
\SetRowColor{LightBackground}
Package statement & -{}-{}-{}-- 1 \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
Import statements & -{}-{}-{}-- 2 \tn 
% Row Count 2 (+ 1)
% Row 2
\SetRowColor{LightBackground}
Comments & -{}-{}-{}-- 3a \tn 
% Row Count 3 (+ 1)
% Row 3
\SetRowColor{white}
Class declaration & -{}-{}-{}-- 4 \tn 
% Row Count 4 (+ 1)
% Row 4
\SetRowColor{LightBackground}
Variables & -{}-{}-{}-- 5 \tn 
% Row Count 5 (+ 1)
% Row 5
\SetRowColor{white}
Comments & -{}-{}-{}-- 3b \tn 
% Row Count 6 (+ 1)
% Row 6
\SetRowColor{LightBackground}
Constructors & -{}-{}-{}-- 6 \tn 
% Row Count 7 (+ 1)
% Row 7
\SetRowColor{white}
Methods & -{}-{}-{}-- 7 \tn 
% Row Count 8 (+ 1)
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{Nested classes, nested interfaces and Enum are not covered Enum}  \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{2.4885 cm} x{2.4885 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{Packages}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{All Java {\emph{classes}} are part of a {\emph{package}}} \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
\mymulticolumn{2}{x{5.377cm}}{If the class has not package definition, it is classified in the {\bf{default}} {\emph{package}} (which doesn't have a name)} \tn 
% Row Count 4 (+ 3)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{Must be the first in the class definition (though you can define comments a above its declaration)} \tn 
% Row Count 6 (+ 2)
% Row 3
\SetRowColor{white}
\mymulticolumn{2}{x{5.377cm}}{The {\emph{package}} statement can't appear within a class declaration or after the class declaration} \tn 
% Row Count 8 (+ 2)
% Row 4
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{Must appear exactly once in a class} \tn 
% Row Count 9 (+ 1)
% Row 5
\SetRowColor{white}
\mymulticolumn{2}{x{5.377cm}}{Classes and interfaces in the same pacakge can use each other without prefixing theier names with the pacakge name} \tn 
% Row Count 12 (+ 3)
% Row 6
\SetRowColor{LightBackground}
The use a class or an interface of another package, you must use its fully qualified name & \seqsplit{`packageName.anySubpackageName.ClassName`} \tn 
% Row Count 17 (+ 5)
% Row 7
\SetRowColor{white}
\mymulticolumn{2}{x{5.377cm}}{Use {\bf{import}} statement to use the simple name of a class or interface} \tn 
% Row Count 19 (+ 2)
% Row 8
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{A package is made of multiple sections that go from the more-generic(left) to the more specific(right)} \tn 
% Row Count 22 (+ 3)
% Row 9
\SetRowColor{white}
\mymulticolumn{2}{x{5.377cm}}{Per java naming conventions, packages names should all be in lowercase} \tn 
% Row Count 24 (+ 2)
% Row 10
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{The package and subpackage names are separated using a dot (.)} \tn 
% Row Count 26 (+ 2)
% Row 11
\SetRowColor{white}
\mymulticolumn{2}{x{5.377cm}}{Package names follow the rules defined for valid identifiers in Java} \tn 
% Row Count 28 (+ 2)
% Row 12
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{For classes and interfaces defined in a package, the {\emph{package}} statement is the first statement in a Java source file (a .java file)} \tn 
% Row Count 31 (+ 3)
\end{tabularx}
\par\addvspace{1.3em}

\vfill
\columnbreak
\begin{tabularx}{5.377cm}{x{2.4885 cm} x{2.4885 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{Packages (cont)}}  \tn
% Row 13
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{The can be a maximum of one {\emph{package}} statement per Java source code file (.java file)} \tn 
% Row Count 2 (+ 2)
% Row 14
\SetRowColor{white}
\mymulticolumn{2}{x{5.377cm}}{All the classes and interfaces defined in a Java source code file are defined in the same package. They can be defined in separate packages.} \tn 
% Row Count 5 (+ 3)
% Row 15
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{The hierachy of classes and interfaces defined in packages must match the hierarchy of the directories in which these classes and interfaces are defined in the code.} \tn 
% Row Count 9 (+ 4)
% Row 16
\SetRowColor{white}
\mymulticolumn{2}{x{5.377cm}}{To enable the Java Runtime Enviroment (JRE) to find your classes, add the base directory that contains your packaged Java code to the classpath} \tn 
% Row Count 12 (+ 3)
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{1.64241 cm} x{3.33459 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{Comments}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{Can appear before and after a {\emph{package}}} \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
\mymulticolumn{2}{x{5.377cm}}{Can appear before and after a {\emph{class}} definition} \tn 
% Row Count 2 (+ 1)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{Can appear before and after a {\emph{method}}} \tn 
% Row Count 3 (+ 1)
% Row 3
\SetRowColor{white}
Multiline comments & /* */ \tn 
% Row Count 5 (+ 2)
% Row 4
\SetRowColor{LightBackground}
Multiline comments & Can contain special characters.  The following is a coding practice (but not required): \{\{nl\}\} /*\{\{nl\}\}* comments that span \{\{nl\}\}* multiple lines\{\{nl\}\}*\{\{nl\}\}*/ \tn 
% Row Count 12 (+ 7)
% Row 5
\SetRowColor{white}
End-of-line comments & // \tn 
% Row Count 14 (+ 2)
% Row 6
\SetRowColor{LightBackground}
Is it valid? & `String name = "\textbackslash{}/* Juan */ Paul";` \tn 
% Row Count 16 (+ 2)
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{Javadoc comments are special comments that start with /** and end with */ (this is processed by Javadoc, a JDK tool to generate API documentation)}  \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{1.74195 cm} x{3.23505 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{Class declaration}}  \tn
% Row 0
\SetRowColor{LightBackground}
Acces modifiers & public/private/protected \tn 
% Row Count 2 (+ 2)
% Row 1
\SetRowColor{white}
Nonacces modifiers & \seqsplit{static/final/abstract/synchronized} \tn 
% Row Count 4 (+ 2)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{Class name} \tn 
% Row Count 5 (+ 1)
% Row 3
\SetRowColor{white}
Name of the base class & if the class is extending another class \tn 
% Row Count 7 (+ 2)
% Row 4
\SetRowColor{LightBackground}
Class body & (class fields, methods, constructors), included \{\} \tn 
% Row Count 9 (+ 2)
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{2.04057 cm} x{2.93643 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{More on classes}}  \tn
% Row 0
\SetRowColor{LightBackground}
class definition & used to specify the attributes ({\emph{variables}}) and behavior ({\emph{methods}}) of an object. \tn 
% Row Count 4 (+ 4)
% Row 1
\SetRowColor{white}
 & A class name starts with the keyword {\emph{class}}. It is cAsE-sEnSiTiVe \tn 
% Row Count 7 (+ 3)
% Row 2
\SetRowColor{LightBackground}
 & The state of a class is defined using {\emph{attributes}} or instance variables \tn 
% Row Count 11 (+ 4)
% Row 3
\SetRowColor{white}
 & It isn't compulsory yo define all attributes of a class before defining its methods. But this is far from being optimal for readability \tn 
% Row Count 17 (+ 6)
% Row 4
\SetRowColor{LightBackground}
Methods & often used to manipulate the instance variables \tn 
% Row Count 20 (+ 3)
% Row 5
\SetRowColor{white}
 & A {\emph{class method}} or {\emph{static method}} can be used to maniplate the {\emph{static}} variables \tn 
% Row Count 24 (+ 4)
% Row 6
\SetRowColor{LightBackground}
Instance \seqsplit{variabls/attributes} & Each object has its own copy of the instance variables \tn 
% Row Count 27 (+ 3)
% Row 7
\SetRowColor{white}
 & The instance variables are defined within a class but outside all methods in a class \tn 
% Row Count 31 (+ 4)
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{2.33919 cm} x{2.63781 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{Interfaces in a Java source code file}}  \tn
% Row 0
\SetRowColor{LightBackground}
Interface in a Java source code file & Types?? \tn 
% Row Count 2 (+ 2)
% Row 1
\SetRowColor{white}
 & Specifies a contract for the classes to implement \tn 
% Row Count 5 (+ 3)
% Row 2
\SetRowColor{LightBackground}
 & Grouping of related methods and constants \tn 
% Row Count 7 (+ 2)
% Row 3
\SetRowColor{white}
 & Starting Java 8, methods in an interface can define a default implementation \tn 
% Row Count 11 (+ 4)
% Row 4
\SetRowColor{LightBackground}
 & Interface can also define {\emph{static}} methods. \tn 
% Row Count 14 (+ 3)
% Row 5
\SetRowColor{white}
 & You can define either a single class or an interface in a Java source code file or multiple such entites. \tn 
% Row Count 19 (+ 5)
% Row 6
\SetRowColor{LightBackground}
 & -able- suffix for interfaces like Comparable?  preffix for interfaces, like IComparable? \tn 
% Row Count 24 (+ 5)
% Row 7
\SetRowColor{white}
 & The classes and interfaces can defined in any order of occurrence in a Java source code file \tn 
% Row Count 29 (+ 5)
% Row 8
\SetRowColor{LightBackground}
 & Classes and interfaces defined in the same Java source code file can't be defined in separate packages. \tn 
% Row Count 34 (+ 5)
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{`interface Controls \{ \newline     void changeChannel(int channelNumber); \newline     void increaseVolume(); \newline     void decreaseVolume(); \newline \} \newline `}  \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{2.4885 cm} x{2.4885 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{Executable Java Applications}}  \tn
% Row 0
\SetRowColor{LightBackground}
What is aexecutable Java class? & An executable Java class, when handed over to the JVM, starts its execution at a particular point in the class-{}- {\emph{main}} method. The JVM starts executing the code that's defined in the {\emph{main}} method. \tn 
% Row Count 10 (+ 10)
% Row 1
\SetRowColor{white}
 & A Java application can define more than one executable class. We have to choose one when the times comes to start its execution by the JVM \tn 
% Row Count 17 (+ 7)
% Row 2
\SetRowColor{LightBackground}
main method & Must be marked {\bf{public}} \tn 
% Row Count 19 (+ 2)
% Row 3
\SetRowColor{white}
 & Must be marked as a {\bf{static}} method \tn 
% Row Count 21 (+ 2)
% Row 4
\SetRowColor{LightBackground}
 & The name of the method must me be {\bf{main}} \tn 
% Row Count 24 (+ 3)
% Row 5
\SetRowColor{white}
 & The return type of this method must be {\bf{void}} \tn 
% Row Count 27 (+ 3)
% Row 6
\SetRowColor{LightBackground}
 & The method must accept a method argument of a {\bf{String}} array or a variable argument (varargs) of type {\bf{String}} \tn 
% Row Count 33 (+ 6)
\end{tabularx}
\par\addvspace{1.3em}

\vfill
\columnbreak
\begin{tabularx}{5.377cm}{x{2.4885 cm} x{2.4885 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{Executable Java Applications (cont)}}  \tn
% Row 7
\SetRowColor{LightBackground}
`public static void main(String... args)` & It's valid \tn 
% Row Count 3 (+ 3)
% Row 8
\SetRowColor{white}
`public static void main(String args...)` & Won't compile \tn 
% Row Count 6 (+ 3)
% Row 9
\SetRowColor{LightBackground}
`public static void main(String{[}{]} hola)` & acceptable \tn 
% Row Count 8 (+ 2)
% Row 10
\SetRowColor{white}
`public static void main(String argumenmtos{[}{]})` & It's ok \tn 
% Row Count 11 (+ 3)
% Row 11
\SetRowColor{LightBackground}
`static public void main(String argumenmtos{[}{]})` & Yes, you can exchange modifiers (ok) \tn 
% Row Count 14 (+ 3)
% Row 12
\SetRowColor{white}
set up to compile or execute from command prompr & \seqsplit{http://docs.oracle.com/javase/tutorial/getStarted/cupojava/index.html} \tn 
% Row Count 18 (+ 4)
% Row 13
\SetRowColor{LightBackground}
D:\textbackslash{}\textgreater{}java hello & Execute a Java app \tn 
% Row Count 19 (+ 1)
% Row 14
\SetRowColor{white}
D:\textbackslash{}\textgreater{}java hello 1 2 & D:\textbackslash{}\textgreater{}java hello with arguments \tn 
% Row Count 21 (+ 2)
% Row 15
\SetRowColor{LightBackground}
 & Java doesn't pass the name of the class as an argument to the main method (like C does) \tn 
% Row Count 26 (+ 5)
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\end{tabularx}
\par\addvspace{1.3em}


% That's all folks
\end{multicols*}

\end{document}