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% Packages
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\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{Jianmin Feng (taotao)}
\pdfinfo{
  /Title (java-core-classes.pdf)
  /Creator (Cheatography)
  /Author (Jianmin Feng (taotao))
  /Subject (Java Core Classes Cheat Sheet)
}

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% Commands
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% Header and Footer
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\fancyhead{} % Set header to blank
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\fancyhead[L]{
\noindent
\begin{multicols}{3}
\begin{tabulary}{5.8cm}{C}
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    \vspace{-7pt}
    {\parbox{\dimexpr\textwidth-2\fboxsep\relax}{\noindent
        \hspace*{-6pt}\includegraphics[width=5.8cm]{/web/www.cheatography.com/public/images/cheatography_logo.pdf}}
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\end{tabulary}
\columnbreak
\begin{tabulary}{11cm}{L}
    \vspace{-2pt}\large{\bf{\textcolor{DarkBackground}{\textrm{Java Core Classes Cheat Sheet}}}} \\
    \normalsize{by \textcolor{DarkBackground}{Jianmin Feng (taotao)} via \textcolor{DarkBackground}{\uline{cheatography.com/79308/cs/19300/}}}
\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}Jianmin Feng (taotao) \\
  \uline{cheatography.com/taotao} \\
  \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 10th May, 2019.\\
   Page {\thepage} of \pageref{LastPage}.
\end{tabulary}
\vfill
\columnbreak
\begin{tabulary}{5.8cm}{L}
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  \mymulticolumn{1}{p{5.377cm}}{\bf\textcolor{white}{Sponsor}}  \\
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  \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}{x{2.04057 cm} x{2.93643 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{Object class}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{Universal superclass, all methods should be overriden if default implement is not suitable.} \tn 
% Row Count 2 (+ 2)
% Row 1
\SetRowColor{white}
toString() & return memory address by default \tn 
% Row Count 4 (+ 2)
% Row 2
\SetRowColor{LightBackground}
equals(); & same as == by default, compare  memory address, not the content \tn 
% Row Count 7 (+ 3)
% Row 3
\SetRowColor{white}
compareTo() & same as \textless{}\textgreater{} by default, memory address instead of content \tn 
% Row Count 10 (+ 3)
% Row 4
\SetRowColor{LightBackground}
hashCode() & return unique integer mapping an object to a hash table. \tn 
% Row Count 13 (+ 3)
% Row 5
\SetRowColor{white}
\seqsplit{Objects.hash(Object...} args) & a simple hash algorithm \tn 
% Row Count 15 (+ 2)
% Row 6
\SetRowColor{LightBackground}
getClass() & polymorphic, return class name \tn 
% Row Count 17 (+ 2)
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{ovrridden equals() usually means override hashCode() too to return the same integer if 2 object are the same.}  \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{2.38896 cm} x{2.58804 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{Wrapper class}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{Wraps ( boxing) or unwraps ( unboxing) primary types to object type} \tn 
% Row Count 2 (+ 2)
% Row 1
\SetRowColor{white}
\mymulticolumn{2}{x{5.377cm}}{1. for methods required object type as parameters} \tn 
% Row Count 3 (+ 1)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{2. for java container classes require object items} \tn 
% Row Count 4 (+ 1)
% Row 3
\SetRowColor{white}
intObj = Integer (6) & boxing int into Integer \tn 
% Row Count 6 (+ 2)
% Row 4
\SetRowColor{LightBackground}
int intObj.intValue() & unboxing \tn 
% Row Count 8 (+ 2)
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\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{Wrapper object are immutable, final}  \tn 
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\par\addvspace{1.3em}

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\mymulticolumn{4}{x{5.377cm}}{\bf\textcolor{white}{8 wrapper class}}  \tn
% Row 0
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Boolean & Byte & Character & short \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
Integer & Long & Float & Double \tn 
% Row Count 2 (+ 1)
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\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{2.38896 cm} x{2.58804 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{Wrapper class constructor}}  \tn
% Row 0
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public Xxxx(xxx) & create from primitive \tn 
% Row Count 2 (+ 2)
% Row 1
\SetRowColor{white}
public Xxxx(String) & create from string \tn 
% Row Count 3 (+ 1)
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{No default constructor; \newline All wrapper classes are final}  \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}--}
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\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Wrapper class methods}}  \tn
% Row 0
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\mymulticolumn{1}{x{5.377cm}}{Overriden toString(), equals() and compareTo() methods based on object content value instead of memory address.} \tn 
% Row Count 3 (+ 3)
% Row 1
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\mymulticolumn{1}{x{5.377cm}}{obj.xxxValue(): used to get primary values} \tn 
% Row Count 4 (+ 1)
% Row 2
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\mymulticolumn{1}{x{5.377cm}}{new Xxx(PARAM): Constructor} \tn 
% Row Count 5 (+ 1)
% Row 3
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\mymulticolumn{1}{x{5.377cm}}{X.parseXxx(String): parse values from string as primitive} \tn 
% Row Count 7 (+ 2)
% Row 4
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\mymulticolumn{1}{x{5.377cm}}{X.valueOf: value from string as Wrapper class} \tn 
% Row Count 8 (+ 1)
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\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{wrapper class equals() check the type first, if not same type return false.}  \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
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\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{2.78712 cm} x{2.18988 cm} }
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\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{Math}}  \tn
% Row 0
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import static java.lang.Math.*; & all members are static \tn 
% Row Count 2 (+ 2)
% Row 1
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\mymulticolumn{2}{x{5.377cm}}{Math.PI} \tn 
% Row Count 3 (+ 1)
% Row 2
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% Row Count 4 (+ 1)
% Row 3
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\mymulticolumn{2}{x{5.377cm}}{Math.power(base, exp)} \tn 
% Row Count 5 (+ 1)
% Row 4
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\mymulticolumn{2}{x{5.377cm}}{Math.sqrt()} \tn 
% Row Count 6 (+ 1)
% Row 5
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Math.random & {[}0,1) \tn 
% Row Count 7 (+ 1)
% Row 6
\SetRowColor{LightBackground}
Math.round() & -0.5-\textgreater{}0,-0.6-\textgreater{}-1, 0.5-\textgreater{}1 \tn 
% Row Count 9 (+ 2)
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\par\addvspace{1.3em}

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\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{Math random numbers}}  \tn
% Row 0
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a*Math.random()+b & a for scale, b=shift \tn 
% Row Count 2 (+ 2)
% Row 1
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(int)(Math,random*a)+b & {[}b,a-1) \tn 
% Row Count 3 (+ 1)
% Row 2
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(int)((Math,random+1)*a)+b & {[}b,a{]} \tn 
% Row Count 5 (+ 2)
% Row 3
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(int)(Math,random*20)+5 & {[}5,24{]} \tn 
% Row Count 7 (+ 2)
% Row 4
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(int)(Math,random*21)+5 & {[}5,25{]} \tn 
% Row Count 9 (+ 2)
\hhline{>{\arrayrulecolor{DarkBackground}}--}
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\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{2.53827 cm} x{2.43873 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{Java random number generators}}  \tn
% Row 0
\SetRowColor{LightBackground}
\seqsplit{java.lang.Math.random()} & double {[}0,1), need scale,shift,casting \tn 
% Row Count 2 (+ 2)
% Row 1
\SetRowColor{white}
java.Util.Random; & flexible types \& methods,reproducible \tn 
% Row Count 4 (+ 2)
% Row 2
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\seqsplit{java.secure.SecureRandom;} & \textless{}=128bit, cryptographically secure \tn 
% Row Count 6 (+ 2)
% Row 3
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\seqsplit{java.util.concurrent.ThreadLocalRandom;} & more efficient with multi-thread app \tn 
% Row Count 8 (+ 2)
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\end{tabularx}
\par\addvspace{1.3em}


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

\end{document}