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\usepackage{MnSymbol}           % Symbols
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% Document Info
\author{Jianmin Feng (taotao)}
\pdfinfo{
  /Title (java-array-and-arraylist-oca.pdf)
  /Creator (Cheatography)
  /Author (Jianmin Feng (taotao))
  /Subject (Java Array and ArrayList (OCA) Cheat Sheet)
}

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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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\columnbreak
\begin{tabulary}{11cm}{L}
    \vspace{-2pt}\large{\bf{\textcolor{DarkBackground}{\textrm{Java Array and ArrayList (OCA) Cheat Sheet}}}} \\
    \normalsize{by \textcolor{DarkBackground}{Jianmin Feng (taotao)} via \textcolor{DarkBackground}{\uline{cheatography.com/79308/cs/19274/}}}
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\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 April, 2019.\\
   Page {\thepage} of \pageref{LastPage}.
\end{tabulary}
\vfill
\columnbreak
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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
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% www.emerson.emory.edu/services/latex/latex_169.html
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\begin{multicols*}{3}

\begin{tabularx}{5.377cm}{x{3.23505 cm} x{1.74195 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{Array Initialization}}  \tn
% Row 0
\SetRowColor{LightBackground}
int {[}{]} a1; int a2{[}{]}; & declarations \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
int {[}{]} a = new int{[}3{]}; & a=\{0,0,0\} \tn 
% Row Count 2 (+ 1)
% Row 2
\SetRowColor{LightBackground}
int {[}{]} a = \{1,2,3\}; & initializer list \tn 
% Row Count 4 (+ 2)
% Row 3
\SetRowColor{white}
int {[}{]} a = new int{[}{]} \{1,2,3\}; & initializer list \tn 
% Row Count 6 (+ 2)
% Row 4
\SetRowColor{LightBackground}
int a{[}{]} = new int{[}{]}; & compile error \tn 
% Row Count 7 (+ 1)
% Row 5
\SetRowColor{white}
int {[}{]} a = new int{[}3{]} \{1,2,3\}; & compile error \tn 
% Row Count 9 (+ 2)
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Array length}}  \tn
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{\seqsplit{System.out.print(a.length);} //3} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Compare:length for Array, length() for String and size() for ArrayList}  \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Loop through Array}}  \tn
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{for (int i=0; i\textless{}arr.length; i++) \{\} //modify \newline for ( int a : arr) \{...\} //access only} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Array as method parameter}}  \tn
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{passing an array is passing the memory address, the change on array content will be persistent through caller and callee.% Row Count 3 (+ 3)
} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Array contents}}  \tn
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{int {[}{]} intArr=\{1,2,3\}  \newline int {[}{]} doubleArr=new double{[}3{]} \newline String {[}{]} objArr = new String{[}3{]}; //object type} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Array Modification}}  \tn
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{Array is fixed in length once initialized, remove an element will resize the array and move all the element on its right. This could be computationally expensive.% Row Count 4 (+ 4)
} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Arrays utilities}}  \tn
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{import java.util.Arrays; \newline Arrays.sort(arr); \newline Arrays.binarySearch(arr,item); \newline //if found, return index \newline //if not return -(potential index -1) \newline //if array not sorted,result is undefined \newline List list=Arrays.asList(arr); \newline Arrays.copyOfRange(Object{[}{]} src,from,to)} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
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\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{toString() method}}  \tn
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{not overloaded, inherited from Object class directly% Row Count 2 (+ 2)
} \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}{Variable arguments varargs}}  \tn
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{public static void main (String {[}{]} args)\{\} \newline public static void main (String... args)\{\} \newline //0 or more arguments \newline //similar to method overloading, or arrays \newline //args are treated as args{[}{]}} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
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\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Multiple dimension array}}  \tn
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{//initialization, first index required \newline int {[}{]}{[}{]} arr = new int{[}4{]}{[}{]}; \newline int {[}{]} arr{[}{]}= new int{[}5{]}{[}{]}; \newline int arr{[}{]}{[}{]}= new int{[}6{]}{[}{]} \newline int {[}{]} arr{[}{]}{[}{]}= new int{[}5{]}{[}{]}{[}{]}; //3D \newline arr=\{\{1,2,3\},{[}4,5,6\}\}; \newline //loop through \newline for (int i=0;i\textless{}arr.length;i++\}\{ \newline    for (int j=0;j\textless{}arr{[}i{]};j++) \{... \} \newline \} \newline for (int innerArr:arr)\{ \newline   for (int num:innerArr)\{...\} \newline \}} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{ArrayList}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{import java.util.ArrayList;} \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{Size dynamically changed at runtime with autoshift} \tn 
% Row Count 2 (+ 1)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{last element indexed by size()-1} \tn 
% Row Count 3 (+ 1)
% Row 3
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{only contains reference type} \tn 
% Row Count 4 (+ 1)
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{2.68758 cm} x{2.28942 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{Array vs ArrayList}}  \tn
% Row 0
\SetRowColor{LightBackground}
{\bf{Array}} & {\bf{ArrayList}} \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
length predefined & size() variable \tn 
% Row Count 2 (+ 1)
% Row 2
\SetRowColor{LightBackground}
manual shift & Auto shift \tn 
% Row Count 3 (+ 1)
% Row 3
\SetRowColor{white}
faster & slower \tn 
% Row Count 4 (+ 1)
% Row 4
\SetRowColor{LightBackground}
primitive+Ref type & ref type only \tn 
% Row Count 5 (+ 1)
% Row 5
\SetRowColor{white}
\seqsplit{ArrayIndexOutOfBoundaryException} & \seqsplit{IndexOutOfBoundaryException} \tn 
% Row Count 7 (+ 2)
% Row 6
\SetRowColor{LightBackground}
equals() not overriden & overriden equals() \tn 
% Row Count 9 (+ 2)
% Row 7
\SetRowColor{white}
toString() not overriden & overriden toString() \tn 
% Row Count 11 (+ 2)
% Row 8
\SetRowColor{LightBackground}
Arrays.sort() & \seqsplit{Collections.sort()} \tn 
% Row Count 12 (+ 1)
% Row 9
\SetRowColor{white}
\seqsplit{Arrays.binarySearch()} & \seqsplit{Collections.binarySearch()} \tn 
% Row Count 14 (+ 2)
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Create ArrayList}}  \tn
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{ArrayList aL1 = new ArrayList(); \newline ArrayList aL2 = new ArrayList(5); \newline ArrayList aL3 = new ArrayList(aL1); \newline  \newline ArrayList\textless{}String\textgreater{} aL4,aL5; \newline aL4=new ArrayList\textless{}String\textgreater{}(); //Java5 \newline aL5 = new ArrayList\textless{}\textgreater{}(); //Java 7 \newline  \newline ArrayList aL6 = Arrays.asList(arr);} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{IllegArgumentException  // when primary type value assigned}  \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{1.04517 cm} x{3.93183 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{Using ArrayList}}  \tn
% Row 0
\SetRowColor{LightBackground}
add & Boolean add(E element) \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
 & void add (int index, E element) \tn 
% Row Count 2 (+ 1)
% Row 2
\SetRowColor{LightBackground}
remove & Boolean remove(Object obj) \tn 
% Row Count 3 (+ 1)
% Row 3
\SetRowColor{white}
 & E remove(int index) \tn 
% Row Count 4 (+ 1)
% Row 4
\SetRowColor{LightBackground}
set & E set(int index, E element) \tn 
% Row Count 5 (+ 1)
% Row 5
\SetRowColor{white}
size & int size() \tn 
% Row Count 6 (+ 1)
% Row 6
\SetRowColor{LightBackground}
 & boolean isEmpty() \tn 
% Row Count 7 (+ 1)
% Row 7
\SetRowColor{white}
clear & void clear() \tn 
% Row Count 8 (+ 1)
% Row 8
\SetRowColor{LightBackground}
\seqsplit{contains} & boolean contains(Object obj) \tn 
% Row Count 9 (+ 1)
% Row 9
\SetRowColor{white}
equals & boolean equals(Object obj) \tn 
% Row Count 10 (+ 1)
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Wrraper class}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{To put primitive type to ArrayList, using wrapper class} \tn 
% Row Count 2 (+ 2)
% Row 1
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{Boolean,Byte,Short,Integer,Long,Float,Double,Character} \tn 
% Row Count 4 (+ 2)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Xxx.parseXxx(String) //convnert string to a primitive} \tn 
% Row Count 6 (+ 2)
% Row 3
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{Xxx.valueOf(String) //convert string to a wrapper class(Xxx)} \tn 
% Row Count 8 (+ 2)
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{NumberFormatException}  \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Autoboxing}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Auto primitive value \textgreater{} wrapper class obj} \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{null allowed boxing into list, print ok,but unboxing is not allowed -{}-\textgreater{} NullPointexception} \tn 
% Row Count 3 (+ 2)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Integer List is interest: int as index is precedent autoboxing. remove(1) will remove second element, not Integer(1)} \tn 
% Row Count 6 (+ 3)
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Convert Between Array and List}}  \tn
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{1. toArray() \newline listObj.toArray();  //convert to obj arr \newline listObj.toArray(new String{[}0{]}); \newline //index= 0 will return a new string array,  \newline //index \textgreater{}0 will reuse if fit, else return new one \newline  \newline 2. AsList() \newline //get a list with fixed size \newline list =Arrays.asList(arrayObj) \newline list.remove(1): //UnsupportedOperation \newline List\textless{}String\textgreater{} args=Arrays.asList("one","two");//varargs \newline // get a new arrayList obj,  \newline ArrayList\textless{}String\textgreater{} aL=new \seqsplit{ArrayList(Arrays.asList("one"},"two"));} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{toArray() is list object method, return new array object \newline asList() is Arrays class static method, return the memory location as a list (same structure shared by array and list, content can be changed by both array and list,size still fixed)}  \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}


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

\end{document}