\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{codekook}
\pdfinfo{
  /Title (java-cheat-sheet.pdf)
  /Creator (Cheatography)
  /Author (codekook)
  /Subject (java 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}{A3A3A3}
\definecolor{LightBackground}{HTML}{F3F3F3}
\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{java Cheat Sheet}}}} \\
    \normalsize{by \textcolor{DarkBackground}{codekook} via \textcolor{DarkBackground}{\uline{cheatography.com/62383/cs/16019/}}}
\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}codekook \\
  \uline{cheatography.com/codekook} \\
  \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 7th June, 2018.\\
   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}{x{0.84609 cm} x{4.13091 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{基本概念}}  \tn
% Row 0
\SetRowColor{LightBackground}
JDK & 开发java用 \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
JRE & 运行java程序用 \tn 
% Row Count 2 (+ 1)
% Row 2
\SetRowColor{LightBackground}
javac & \seqsplit{java编译器，源代码} -\textgreater{} \seqsplit{字节码（.class文件）} \tn 
% Row Count 4 (+ 2)
% Row 3
\SetRowColor{white}
\seqsplit{bytecode} & \seqsplit{java字节码，包含java虚拟机能识别的指令集} \tn 
% Row Count 6 (+ 2)
% Row 4
\SetRowColor{LightBackground}
JVM & \seqsplit{java虚拟机，能将java字节码翻译成机器码来执行} \tn 
% Row Count 8 (+ 2)
% Row 5
\SetRowColor{white}
jar & \seqsplit{一种压缩文件，将多个}.class文件打包到一起 \tn 
% Row Count 10 (+ 2)
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{1.23579 cm} x{1.87657 cm} x{1.46464 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{3}{x{5.377cm}}{\bf\textcolor{white}{数据类型}}  \tn
% Row 0
\SetRowColor{LightBackground}
{\bf{类型}}\{\{bb\}\} & {\bf{长度（位）}}\{\{bb\}\} & {\bf{默认值}}\{\{bb\}\} \tn 
% Row Count 2 (+ 2)
% Row 1
\SetRowColor{white}
byte & 8 & 0 \tn 
% Row Count 3 (+ 1)
% Row 2
\SetRowColor{LightBackground}
short & 16 & 0 \tn 
% Row Count 4 (+ 1)
% Row 3
\SetRowColor{white}
char & 16 & \textbackslash{}u0000 \tn 
% Row Count 5 (+ 1)
% Row 4
\SetRowColor{LightBackground}
int & 32 & 0 \tn 
% Row Count 6 (+ 1)
% Row 5
\SetRowColor{white}
long & 64 & 0L \tn 
% Row Count 7 (+ 1)
% Row 6
\SetRowColor{LightBackground}
float & 32 & 0.0F \tn 
% Row Count 8 (+ 1)
% Row 7
\SetRowColor{white}
boolean & 未指定 & false \tn 
% Row Count 9 (+ 1)
\hhline{>{\arrayrulecolor{DarkBackground}}---}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{1.55618 cm} x{1.60195 cm} x{1.41887 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{3}{x{5.377cm}}{\bf\textcolor{white}{类型转换}}  \tn
% Row 0
\SetRowColor{LightBackground}
{\bf{表达式}}\{\{bb\}\} & {\bf{结果类型}}\{\{bb\}\} & {\bf{结果值}}\{\{bb\}\} \tn 
% Row Count 2 (+ 2)
% Row 1
\SetRowColor{white}
(1 + 2 + 3) / 4.0 & double & 1.5 \tn 
% Row Count 4 (+ 2)
% Row 2
\SetRowColor{LightBackground}
11 * 2.0F & float & 22.0 \tn 
% Row Count 5 (+ 1)
% Row 3
\SetRowColor{white}
(int) 11 * 2.0 & double & 22.0 \tn 
% Row Count 7 (+ 2)
% Row 4
\SetRowColor{LightBackground}
11 * (int) 2.0 & int & 22 \tn 
% Row Count 9 (+ 2)
% Row 5
\SetRowColor{white}
(int)(11 {\emph{ 2.0 }} 2.0) & int & 44 \tn 
% Row Count 11 (+ 2)
% Row 6
\SetRowColor{LightBackground}
1 + 2L & long & 3 \tn 
% Row Count 12 (+ 1)
% Row 7
\SetRowColor{white}
(int) (1 + 2L) & int & 3 \tn 
% Row Count 14 (+ 2)
\hhline{>{\arrayrulecolor{DarkBackground}}---}
\SetRowColor{LightBackground}
\mymulticolumn{3}{x{5.377cm}}{隐式转换： \newline int -\textgreater{} long -\textgreater{} float -\textgreater{} double \newline 显式转换：int i = (int) 2.20 \newline 可能会丢失数据精度}  \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}---}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{0.9154 cm} x{1.55618 cm} x{2.10542 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{3}{x{5.377cm}}{\bf\textcolor{white}{命名规范}}  \tn
% Row 0
\SetRowColor{LightBackground}
类名\{\{nobreak\}\} & FileReader & 首字母大写 \tn 
% Row Count 3 (+ 3)
% Row 1
\SetRowColor{white}
包名 & cn.hchaojie\{\{nl\}\}.blog.article & 全部小写\{\{nl\}\}域名倒写+应用名+模块名 \tn 
% Row Count 6 (+ 3)
% Row 2
\SetRowColor{LightBackground}
变量 & fileReader & 首字母小写 \tn 
% Row Count 7 (+ 1)
% Row 3
\SetRowColor{white}
常量 & DAY\_OF\_WEEK\{\{nobreak\}\} & \seqsplit{全部大写，下划线分割} \tn 
% Row Count 9 (+ 2)
\hhline{>{\arrayrulecolor{DarkBackground}}---}
\SetRowColor{LightBackground}
\mymulticolumn{3}{x{5.377cm}}{\seqsplit{命名要具有可读性、区分性} \newline 采用驼峰形式 \newline 不要使用中文；除了常量，不要用下划线； \newline 不要用无意义的名字}  \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}---}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{3.23505 cm} p{1.74195 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{java.lang.Math}}  \tn
% Row 0
\SetRowColor{LightBackground}
max(3, 100) & 100 \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
min(3, 100) & 3 \tn 
% Row Count 2 (+ 1)
% Row 2
\SetRowColor{LightBackground}
abs(-3) & 3 \tn 
% Row Count 3 (+ 1)
% Row 3
\SetRowColor{white}
pow(2, 10) & 1024.0 \tn 
% Row Count 4 (+ 1)
% Row 4
\SetRowColor{LightBackground}
pow(4, 0.5) & 2.0 \tn 
% Row Count 5 (+ 1)
% Row 5
\SetRowColor{white}
sqrt(4) & 2.0 \tn 
% Row Count 6 (+ 1)
% Row 6
\SetRowColor{LightBackground}
log(2) & 1.0 \tn 
% Row Count 7 (+ 1)
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{4.03137 cm} x{0.94563 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{字符串格式化}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{System.out.printf(format, arg1, arg2)} \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
\mymulticolumn{2}{x{5.377cm}}{String.format(format, arg1, arg2)} \tn 
% Row Count 2 (+ 1)
% Row 2
\SetRowColor{LightBackground}
\%d & \seqsplit{integer} \tn 
% Row Count 3 (+ 1)
% Row 3
\SetRowColor{white}
\%s & string \tn 
% Row Count 4 (+ 1)
% Row 4
\SetRowColor{LightBackground}
\%f & double \tn 
% Row Count 5 (+ 1)
% Row 5
\SetRowColor{white}
String.format("\%.2f", 20.9988) & 20.99 \tn 
% Row Count 6 (+ 1)
\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}{java.lang.String}}  \tn
% Row 0
\SetRowColor{LightBackground}
length() & 求长度 \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
toUpperCase() & 转大写 \tn 
% Row Count 2 (+ 1)
% Row 2
\SetRowColor{LightBackground}
toLowerCase() & 转小写 \tn 
% Row Count 3 (+ 1)
% Row 3
\SetRowColor{white}
chartAt(0) & 按位置取字符 \tn 
% Row Count 4 (+ 1)
% Row 4
\SetRowColor{LightBackground}
equals() & 判断相等 \tn 
% Row Count 5 (+ 1)
% Row 5
\SetRowColor{white}
startsWith(prefix) & \seqsplit{是否以字符串开头} \tn 
% Row Count 7 (+ 2)
% Row 6
\SetRowColor{LightBackground}
endsWith(suffix) & \seqsplit{是否以字符串结尾} \tn 
% Row Count 9 (+ 2)
% Row 7
\SetRowColor{white}
split(delimiter) & 以分隔符切分 \tn 
% Row Count 10 (+ 1)
% Row 8
\SetRowColor{LightBackground}
String.join() & 以分隔符连接 \tn 
% Row Count 11 (+ 1)
% Row 9
\SetRowColor{white}
indexOf() & 子字符串位置 \tn 
% Row Count 12 (+ 1)
% Row 10
\SetRowColor{LightBackground}
replace() & 替换子字符串 \tn 
% Row Count 13 (+ 1)
% Row 11
\SetRowColor{white}
valueOf() & 数字转字符串 \tn 
% Row Count 14 (+ 1)
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{0.89586 cm} x{4.08114 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{面向对象}}  \tn
% Row 0
\SetRowColor{LightBackground}
class & {\bf{类}}、对象的一个{\bf{模板}} \tn 
% Row Count 2 (+ 2)
% Row 1
\SetRowColor{white}
\seqsplit{instance} & 根据类模板创建的一个个{\bf{实例}} \tn 
% Row Count 4 (+ 2)
% Row 2
\SetRowColor{LightBackground}
object & 一个实例也叫一个{\bf{对象}} \tn 
% Row Count 6 (+ 2)
% Row 3
\SetRowColor{white}
\seqsplit{reference} & {\bf{引用}}，给对象取的一个名字，通过引用来操作对象 \tn 
% Row Count 9 (+ 3)
% Row 4
\SetRowColor{LightBackground}
\seqsplit{package} & {\bf{包}}， \seqsplit{是对类的一种组织形式} \tn 
% Row Count 11 (+ 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}{类结构}}  \tn
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{public class Employee \{ \newline     // \seqsplit{成员变量，也叫域、字段、实例变量} \newline     private String idNum; \newline     private String name; \newline     private int age; \newline  \newline     // 构造器 \newline     public Employee(String id) ... \newline     public Employee(String id, String name) \newline  \newline     // 方法 \newline     public String toString() ... \newline     public void setName() ... \newline \}} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}


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

\end{document}